Imagine you are getting ready for bed, the kids are moved out of the house and you turn the thermostat down to a nice cool temperature to sleep. The problem is your air conditioner will cool your entire home even though you just need the master bedroom cool at night. Or picture the scenario that you are at your home office, no one else is home and you don’t really need to cool the second floor of your home during the day while you spend the majority of your time on the first floor. These scenarios are ideal for a zoned damper system that can open and close a damper system, at the touch of your thermostat, to push more air to the rooms that need to be cooler and then go back to normal operation, or flip the airflow, later in the day.
Zoning has become more popular in homes but the performance can vary highly depending on the zoning design, zoning type and installation. We have seen many problems with zoning systems that homeowners inherit would consideration to how you actually live and use the home. Other issues with zoning are in the type of system used sacrifice air conditioning performance and need to be redesigned. Let’s start with defining what zoning is below.
What Is Zoning?
Zoning is a way to push more air into occupied rooms and less air into other unoccupied rooms. Zoning divides your home into areas with common heating and cooling requirements. Each zone is controlled by its own thermostat, allowing you to be comfortable no matter where you are in your home. Zoning with automatic dampers allows you to leave unoccupied areas with less heating or cooling and pushing more air into occupied rooms, saving you more money on energy costs with a thermostat sensor in each zone. If installed correctly and the customer is educated on the zoning system, zoning can save significantly on energy bills.
Once dampers are installed, how does that impact the system design as well as the performance of the system and the comfort of your home? We will cover those questions as well as the alternatives and costs of zoning in this post.
Temperature Zoning Is Highly Recommended If Your Home Has:
Temperature Zoning Is Highly Recommended If You:
Alternatives To Zoning
1. Ductless Mini Split Systems. Ductless mini split systems are a very effective way at cooling a specific room(s) on demand. Mini split systems can be turned off when not in use i.e. a master bedroom during the day, and then used solely at night when the room is in use, saving energy by turning the main thermostat up several degrees during the night. They require a high voltage power source be run and higher in cost, see our article on How Much Does A Mini Split Cost. Mini split systems are ideal for bedrooms, additions or garages that require additional cooling on demand.
2. Manual Disc Dampers. Disc dampers are like zoned dampers but need to be adjusted manually rather than electronically adjusted zoned dampers. Disc dampers are significantly less expensive than zoned dampers or mini split system but the costs for future adjustments can add up. At Green ID we have recommended and installed disc dampers on dozens of homes and like this solution
3. Rerouting the Ductwork. If the ductwork was not installed correctly and a bad imbalance is present, it may be best to simply reroute the ductwork with a disc damper system. A new supply plenum may be required to ensure enough space for each duct but the results can be very good.
4. Energy upgrades like sealing the ductwork, adding new returns, installing jump ducts, increasing insulation and using shade screens can often make your home or hot room much more comfortable and lower your energy bills. With energy upgrades like these you get a whole home solution with several benefits rather than a single solution with a single benefit. Both APS and SRP have rebates available to make these energy improvements to your home
Why Would You Ever Want Zoning In Your Home?
On one side zoning just adds to the cost of an HVAC system and labor. It adds a lot of complexity to the system as well, and this is where most air conditioning contractors get hung up. It also increases the risk of call backs. At Green ID, we have gotten dozens of calls from customers in brand new homes that have zoning systems they don't understand.
On the other side, zoning is all about improving comfort.
But what about in a two story home where you can zone by floor and when everyone goes to bed at night on the second floor, having the ability to shut the airflow down to the first floor so everyone is nice a cool in a Phoenix summer? Isn't that an ideal situation? What about when the morning sun blasts one side of the house but by the afternoon, the entire opposite side of the house now requires much more capacity while the morning side only needs a portion of airflow to keep it comfortable.
Types of Zoned Systems
When you zone for comfort there are really three ways to do that, you can:
1. Zone by equipment and have one AC system for the 2nd floor and one AC system for the 1st floor. If this were my home, this is what I would request. The problem with this is oversizing a system can be very easy and the cost goes up.
2. Zone by refrigeration from ductless mini split systems. This is ideal for additions or specific rooms you want to cool on demand.
3. Zoning by airflow with dampers and which is what this post is about.
Energy savings can vary based on the equipment type and how we manage excess air (through bypass dampers). Depending on how our customers like to live, there can be substantial energy savings from having a zoned system.
One of the goals of zoning is to to manage excess air well. The best practice is to keep the HVAC system as small as possibly can. One of reasons to do this is because at 3 pm in Phoenix, AZ, our western walls are going to demand a much higher load than the eastern side so a good zoned system will close down the dampers to the east side of the house to accommodate for the larger western loads. The larger the HVAC system is oversized, the more we are going to have to manage that excess air and "waste" it in a bypass duct that directly connects the supply and return plenums to feedback excess air. I call it a waste because you have already paid to condition this air and it is not reaching the rooms inside but going directly back into the return to avoid building up high supply static pressures.
We also need to account for larger duct size requirements in zoned systems than a typical non-zoned system. Typically our Manual D designs call for 15-25% larger duct sizing to accommodate the larger, focused loads. The nice thing about zoned dampers though is that if we put in an 8" damper designed for peak loads at 3 pm, at 12 pm our damper will be only partially open and will act like a 6"" duct and at 9 am our damper will continue to modulate to act like a 4" duct. This is like a variable speed airflow system. It's not too far a stretch to see how well this can work with a high efficiency, variable speed compressor and inverter technology.
Why Is A Bypass Damper Needed?
Certain systems do not require a bypass damper but there are many that do and it is more common to see bypass dampers in the field. In my opinion you take away the advantage that zoning gives when you add a bypass damper but why are they installed in the first place? When the zoning manual was developed by ANSI and ACCA one of the Golden Rules of HVAC Design was to do no harm to the equipment, and this is what the bypass damper is used for. It is used to prevent damage to the HVAC system from a high buildup of back pressure in the ductwork by closing zones off. Bypass dampers are inefficient and have been outlawed in California because of the wasted air. Many manufacturers are now offering by-pass eliminator controls which uses closed zone dampers to bleed them open when the pressure build-up in the ductwork exceeds the set-point so it doesn't "waste" the conditioned air.
Let's say that you have a 3 ton heat pump delivering 1200 CFM of air and have one zone that only requires 360 CFM of air to be delivered. That means you have 840 CFM of air that is extra and we have to figure out what to do with. That's what the bypass and damper stops are used for... to recycle the air back to the return and dump air to the rest of the house where it's not needed. This can cause the efficiency and capacity of the system to go down with lower airflow conditions. This can be good if you live in a high humidity climate but in Phoenix we only experience humidity during the Monsoon season of July- August.
Bypass Dampers Are Dumb
John Proctor from Proctor Engineering has famously said "bypass dampers are dumb," are and shown a 32% savings by getting rid of the bypass dampers. You get more airflow rather than putting the conditioned air in a circle so it's obvious that not having a bypass damper is good choice. At Green ID we also do not recommend bypass dampers and design our zoning systems to get the highest performance without sacrificing efficiency.
Problems With Zoning - Things to Watch Out For
Most manufacturers only have spring loaded dampers. These dampers cannot modulate and only have 100% open or 100% close, there is no in-between. Spring loaded dampers will duty cycle to deliver capacity. At 3 pm during the hottest part of the day, spring loaded dampers work fine but what about from 9 am - 12 pm when we aren't at the peak heat of the day? You may experience temperature swings because they deliver too much or too little capacity and still have comfort issues. Modulating dampers are preferred because they can go from 25% to 100% in 1% increments to get a balance between airflow and the load of the zones.
Ductwork Sizes Do Not Change
When installing a zoned system on an existing HVAC unit and duct system, the ductwork sizes may need to be changed. Image you have a hot master bedroom in the summertime and you put it on it's own zone so at night you can push more air into the room and make it comfortable. Now we have created a new problem because the master bedroom ducts are 10" and we are asking it to handle 20% more airflow so a 10" duct won't be adequate anymore.
Designing A Zoned System On An Existing Home
Step 1 - Site Assessment. On an existing home Green ID will perform a site assessment, take room by room measurements and conduct a needs analysis. Our owner will discuss zoning options and alternatives for you to make an informed decision. This is different from our normal energy audits or air conditioning inspections and start at $79 for a 2100 sq ft, two zoned system.
Step 2 - Installation. Once your zoned system is designed and ordered a Green ID team will take care of the installation ensuring a smooth transition for total airflow control.
Step 3 - Commissioning and Post Testing. After your zoned system is installed we will commission it by measuring airflow in each zone, ensuring the system operates exactly as planned.
System Reliability Can Be A Problem When Dampers Are Installed Improperly
On existing homes, we have come across more homeowners that want to remove their zoned system than keep them. This can be from poor performance of the HVAC system once the zoned system are installed. Common problems with poorly designed or installed zoned systems are flooding the compressor, poor airflow
How Much Does Zoning Cost?
How much a zoned system costs on an existing home depends on the number of zones, attic accessibility, the type of zoned system and type of thermostats. At Green ID we design a system based on your use of the home and perform a basic design for $99. The typical cost of a zoned system installed in a retrofit, existing home application is below.
Who Makes The Best Zoning System?
Would A Bigger A/C System Help With A Zoned System?
Not necessarily and often it will work against zoning because a larger air conditioner will put more volume of air through the ductwork and if your ductwork doesn’t also change in size, the larger pressures will make the A/C unit work harder and could potentially be damaging because of high static pressure. A good Manual J load calculation, Manual D duct design and interview is required to properly size the system and it’s typically the ductwork that needs to be increased in size first if you are thinking of increasing the size of your A/C system. A zoned system does work very well with a variable speed compressor though and the size of the system does not have to be increased.
Do you live in an older home that needs an insulation upgrade? Having a thick insulation layer is like wrapping your house in a blanket to keep it warm in the winter and cool in the summer. There are three general types of insulation; cellulose (which is recycled newspaper), loose fill fiberglass (which looks like pink snow), and rolled fiberglass batts (which are itchy and difficult to install correctly).
What is loose fill insulation?
Loose fill insulation consists of small particles of fiber, foam, or other materials. These small particles form an insulation material that can conform to any space without disturbing structures or finishes. This ability to conform makes loose-fill insulation well suited for retrofits and locations where it would be difficult to install other types of insulation.
When you look at insulation and notice a fibrous material in it, you are looking at loose fill insulation. The fibrous material is made out of different recyclable materials, all treated to be resistant to heat. Since the materials are all recyclable, loose fill insulation is often considered to be environmentally friendly.
The most common types of materials used for loose-fill insulation include cellulose, fiberglass, and mineral (rock or slag) wool. All of these materials are produced using recycled waste materials. Cellulose is primarily made from recycled newsprint. Most fiberglass contains 20% to 30% recycled glass. Mineral wool is usually produced from 75% post-industrial recycled content.
Loose fill insulation can be installed in either enclosed cavities such as walls, or unenclosed spaces such as attics. Because loose fill insulation consists of fluffy strands of fiber blown into attics and walls, a special machine is used. It fills nooks and crannies, which eliminates cold and hot spots.
Different types of loose fill insulation
When insulating your home, you can choose from many types of insulation. To choose the best type of insulation for your home, you should first determine the following:
Blown in cellulose
Cellulose loose fill insulation uses recyclable materials such as old boxes and newspapers. These materials are reduced and pulverized, making them into the filler of the insulation. After that, chemicals are mixed into the composition to make it resistant to fire and pests.
This fiber is packed tightly into closed building cavities, which inhibits airflow.
The major disadvantage to cellulose is that it absorbs water, which can become a problem if water leaks from the outdoors. Too much water can also wash away the fire retardant.
Advantages of Cellulose Insulation: Effective at all temperatures.
Disadvantages of Cellulose Insulation: Oftentimes too heavy for attic insulations; ceiling must have at least 5/8 inch drywall or framing every 16 inches. Over time, it can settle almost 20%, reducing its effectiveness.
Best use: ceilings, enclosed existing wall or open new wall cavities, unfinished attic floors, other hard to reach places
Cost: $0.65-$1.10 per SF
Fiberglass loose fill insulation is created when glass is melted and spun into small fibers. These small fibers serve the same purpose as the pulverized and treated boxes and newspapers in cellulose insulation. Loose fill fiberglass insulation must be applied using an insulation-blowing machine in either open-blow applications (such as attic spaces) or closed-cavity applications (such as those found inside walls or covered attic floors).
Advantages of Fiberglass Insulation: widely available and familiar, standard widths and thicknesses are designed to fit between studs, joists, and rafters.
Disadvantages of Fiberglass Insulation: Can be itchy to install. Rolls of fiberglass (which we do not recommend due to the fact that in order for them to be effective, they must be installed perfectly, which is a near impossible task) must be cut by hand to fit into spaces. It compresses easily, which causes it to lose insulating properties over time.
Cost: 0.75-$1.20 per SF
The term R-Values refers to the measurement of thermal resistance of the insulation. The higher the R-value, the more the insulator is resistant to heat flow. The level of R-value you need for your home is determined by your cooling and heating system, together with the climate in your region.
Each material, and often each brand of the material, has a different R-value. It is also important to remember that the maximum R-value of insulation is very dependent on proper installation.
R-30 insulation in the attic is code, which translates to 10” of cellulose. In Phoenix, R-38 is Energy Star standard and the level that we recommend.
You can find the current R-value of your insulation from the manufacturer’s specifications, or use the BPI R-value table, which is simplified below:
If you think that your home needs an insulation upgrade, make sure that you know the pros and cons to each insulation type in order to make the decision that is best for your home!
As Aeroseal dealers, Green ID obviously uses and believes in the product. We have performed dozens of Aeroseals on all types of homes. One advantage we have is that our services also include energy audits and ductwork pressure testing, manually sealing the ductwork, Manual D duct design and sizing, installing new and modifying existing ductwork, and air balancing. This exposes us to a wide range of comfort, efficiency and health and safety conditions related to the ducts and improves all aspects of our work but in particular, the Aeroseal process. In similar way to how weight training will improve a swimmer’s time, performing energy audits lets us test the leakage at each register and use zonal pressure readings to find where major leaks are occurring before we even go in the attic. Manually sealing the ductwork physically puts us in front of each duct so we can see mistakes and gain experience where we might need to put a set of eyes on common problems areas. Ductwork sizing and design lets us know how to set realistic expectations for Aerosealing and know when to use it as a comfort solution, energy saving solution or efficiency improvement and know when another recommendation is better suited to solving a homeowner’s comfort, dust or efficiency problems.
What is Aerosealing?
Aeroseal is a method to seal the ductwork from the inside using a hot polymer glue. The Aeroseal machine gets connected to one of the ducts with a clear plastic tubing while all the other registers are sealed off and isolated from the evaporator coil / heat exchanger. Once connected, the Aeroseal machine uses a fan, heater and manometer to pressurize the ductwork and spray the aerosized glue through the ducts. Its’ ingredients are those commonly found in pacifiers and chewing gum and are non-toxic.
The Benefits of Aeroseal Are:
DOE studies have shown the benefits of Aeroseal, you can read the report here and include.
What Are Aeroseal’s Limitations?
This is Aeroseal’s standard benefit list but what it doesn’t tell us is how much each of these benefits will apply to your home. In some cases, the there will be no noticeable dust change because the dust is coming from a dryer vent or air leak. In other cases, Aeroseal really won’t improve your comfort because the sizing of the ductwork is main cause of comfort issues. Some homes will see no improvement in their energy bills but their dust will be reduced noticeably. The best way to find out how these interplay is to have a comprehensive energy audit on your home.
Aeroseal’s biggest limitation is that it can only seal holes smaller than 5/8”, which is pretty small. Leaks in the ductwork that are larger than 5/8” must be sealed manually first. This can be a problem if your duct system has larger leaks because Aerosealing is more expensive than manually sealing the ductwork but won’t get to the heart of your duct leakage problem. Another limitation is the actual Aeroseal company, especially if they are a larger solar or HVAC company, their Aeroseal crew likely won’t go in the attic to find the larger leaks. I’ve come behind these companies to find that they did not go in the attic during the Aerosealing to manually seal the larger leaks and were either to lazy or not well trained to find the more important, larger leaks in the system.
What’s Better Aeroseal Or Manual Duct Sealing?
Companies that only perform Aeroseal would have you believe that Aeroseal gives a far superior seal on leaky ductwork but that’s not true. The truth is that because Aeroseal seals the ducts from the inside, we don’t need access to the ductwork to seal it, so Aeroseal is better suited for those homes. Examples of homes with inaccessible ducts are on a metal trunk system, 1st floor ductwork on a two story home, or on flat roofs. On these homes, Aeroseal is preferred to solely manually sealing the ductwork, but a manual duct seal still needs to be done on these homes when feasible.
If the ductwork is fully accessible, then manually sealing the ductwork with mastic is more effective and less costly than Aerosealing. Why is manually sealing the ductwork more effective than Aeroseal? It’s because we can apply a much thicker layer with a more rigid backing on larger leaks than Aeroseal applies. A thicker layer of mastic will obviously last longer than a thin layer and hold up again the ductwork expanding and contracting over time. On most tract homes, the ductwork is 100% accessible and a manual duct sealing can be done with good results.
Part of the Aeroseal process can be similar to running a blower door test on a home. If you’ve had an energy audit done, you’ll be familiar with this test. A blower door is a diagnostic tool our energy auditors use to put the home under pressure to measure and find air and ductwork leakage. You can actually feel where the leaks are coming from when under a negative pressure around leaky doors, windows, duct registers, pocket doors, etc. During an Aerosealing, we isolate the ductwork and put the duct system under a similar positive pressure test. During this test we can again feel where the leaks are coming from in the ductwork, however we are able to put the ductwork under a much greater pressure where you can really hear, and feel where the leaks are coming from. Once we take a crawl around the attic and check the HVAC system, I’ve been surprised to discover “hidden” leaks in the ductwork I would have never found from doing a manual seal alone. As both Aeroseal and manual duct seal installers, we learn a lot going back and forth from manually sealing the ductwork to doing Aerosealing and here are some nuggets we’ve learned over the years.
How Aerosealing Has Made Me Better At Ductwork Sealing
How Much Does Aerosealing Cost?
Aeroseal costs can vary between $1600 - $2300 per unit. Manually sealing the ductwork costs can vary between $900 - $1200 per unit. These costs can vary depending on the accessibility of the HVAC unit, the type of HVAC system, the number of registers in the home, the height and access to each register and how many systems are being sealed at one time. Visit Aeroseals website for more information on their product or contact Green ID to see if Aeroseal makes sense for your home.
If you are considering having a home energy audit, here are some reasons why and why not to get a home energy audit. I also address some common misconceptions about energy audits to help you make an informed decision. In Phoenix, for existing homes older than 5 years, the cost is only $99 for an energy audit which is much less than a home inspection and quite possibly a much better investment for your money. A good energy audit is based on the numbers of the tests performed, a consideration of your lifestyle at home and combines those with the experience of energy auditor to find the best ways to reduce energy bills, fix hot rooms and improve air quality.
Sometimes the best thing we find is that there was nothing to find. Other times it can seem like the list of recommendations is endless. Either way you are more informed than when you started. At Green ID we are passionate not only about energy savings and comfort but also if we can get you to NOT invest $20,000 on new windows, Intellifilm, solar attic fans and radiant barrier chips, that’s a win too. Here is what the DOE says about Energy Audits.
Common Misconceptions of Home Energy Audits
It's All About The Windows
Sun struck windows are always a weak point in a home’s thermal envelope. If a window gets more than two hours of direct sunlight, it’s cost effective to put a shade screen on the exterior of the window but no more. Even on single pane windows where the windows won’t even close right, it’s never cost effective to replace your windows and you will never save 30% on your energy bills by changing windows. We have done hundreds of energy models and the numbers never show that replacing windows are cost effective in a hot dry climate like Arizona. Many homeowners believe that leaky, old windows are the main cause of their hot rooms or high energy bills and that’s just not true. Save yourself $20,000 and skip replacing the windows for a solar panel system that will save much more money.
You Won’t Learn Anything New From The Energy Audit
Yes you can do things on your own. I’ve written an entire new post about how to do a DIY home energy audit and there are still tests and knowledge an energy auditor will be able to do that you can learn from. It doesn’t matter if you’re an engineer, doctor, facilities manager, HVAC technician, electrician, window guy, home inspector, real estate agent or even a commercial energy auditor, you don’t know everything about your home that an energy auditor will find. Can you learn it?... of course you can. Being a good energy auditor requires knowledge of building science, being a good detective and getting your hands dirty and crawling around attic spaces all while being focused around solving home durability, comfort, health and safety and efficiency problems. We do this day-in and day-out and that’s where the biggest difference between energy auditors and the other trades lie. Seeing 500 homes a year, plus weekly meetings and training, performing installations and gaining customer feedback gives makes us home energy experts.
You Can’t Do Anything Because Of A Flat Roof
Flat roofs have a layer of urethane spray foam protecting the inside of the house from the extreme Arizona heat. Just because no access can be gained doesn’t mean that the ductwork is sealed or that the insulation is good. A thermal imaging camera can identify missing insulation without tearing down walls and a pressure pan leakage test measures the ductwork leakage on each register, pinpointing areas of high leakage. For homes with inaccessible ductwork, we recommend Aeroseal for the ductwork, which seals the ductwork from the inside. For homes with insulation deficiencies, we assess whether it is severe enough to cut an access into the attic to correct the problem. In cases with just a small amount of insulation defects, it is not worth the drywall removal and repair. In cases that have a large amount of missing or low insulation, it is worth the extra cost. The good news is that in some homes we can access the attics from roof vents or interior attic accesses.
That annoying light you can see around your doors is not wasting as much energy as you think.
In Phoenix, gaps around your doors that let light inside are obvious energy wasters, letting the hot summer air creep inside all day long. This type of air leakage is highly visible and stays top of mind for most people thinking about ways to save energy however that’s not the case in Arizona. We have run the numbers hundreds of times and air sealing those gaps around the doors saves less than $5 a year. My wife calls me a penny pincher on my good days and a cheap bastard on my bad ones and I won’t deny it. There was a time where I tail-gated semi trucks to save on gasoline because the wind resistance is less the closer you can get to the semi trucks and therefore you get more miles to the gallon… not the safest way to save a buck and I’ve seen stopped that practice. So if I can save $5 a year with a DIY weatherstripping improvement I will do it. I’ll also take off all my electrical and light outlet covers and put socket sealers behind the cover plates, knowing it’s not going to save me much money but that it will save something.
Green ID our energy audits focus on all types of energy saving methods, from the no cost thermostat management strategies all the way to HVAC improvements. However your money and energy are best spent on big improvements that have a larger impact on reducing your energy bills and fixing hot rooms. Why spend $100 to save $5 a year (a 20 year ROI) when you could spend $1000 and save $200 a year (a 5 year ROI).
All Home Energy Audits Are Not The Same
I’ve seen companies that have paid energy audits come back as fluff either because the energy auditor was inexperienced or is more sales oriented. Typically companies that are mainly insulation, HVAC or do solar as their main business are not good energy auditing companies. The energy auditors are typically inexperienced or the company pushes their main services and overlooks other defects, however bad they may be. Inexperienced energy auditors tend to focus on the wrong things like air leakage around canned lights and misses easy energy saving fixes like changing the settings on a recirculation pump. If the company primarily does insulation for example, I’ve seen recommendations completely miss airflow problems. HVAC companies may be strong in fixing broken air conditioners but ask them to find thermal bridges in the insulation and you’ll get a blank stare back.
The Truth About Free Energy Audits
In general I would skip over the free energy audits, which are really just sales presentations and estimates. The harm in these free audits is what they miss by not doing a thorough inspection. There is no way to visually look at the ductwork and tell how much the entire system let alone one duct line is leaking. This is important because duct leaks are often hidden under the outer and insulative liners covering the actual connections of the ductwork. Flex ducts could be in hard to reach out shoots of the attic under firewalls and I doubt a commissioned sales person is going to want to crawl around your attic to find out.
Insulation defects are another commonly missed item during a free energy audit that should be identified during a complete energy audit. If a sales person just sticks their head up the attic hatch or never goes past the plywood walkway in the attic- you can expect a cookie-cutter solution that will not fix any insulation defects and when the installers come to do the work…guest what? They won’t know what they are looking for and literally blow right over the problem.
The Interview Is Valuable
Living in the home, you have valuable insight for an energy auditor. Smells, comfort and temperature differences, how the temperature changes throughout the day, weird HVAC tendencies, how you use the home, how many people live in the home, temperature settings at each thermostat all give us clues that we can’t “test” during our time in your home.
When Is A Home Energy Audit Not Worth It
Obviously, Green ID does home energy audits but that doesn’t mean that every home needs an energy audit. Here is a list of when an energy audit may not be needed.
A Home Audit Is Ideal If You Have...
A Home Energy Audit Is Worth It Even If You Have:
DIY Home Energy Audit
Yes, there are certainly items you can do yourself to check your energy usage and perform your own audit. Depending on how comfortable you are crawling around your attic, you can even search for obvious duct leakage around connecting ducts. Here are some DIY energy saving checks to do your own energy audit.
What Can A Paid Energy Audit Find That A DIY Energy Audit Cannot?
An energy auditor will have a blower door to depressurize the ductwork and actually measure the duct leakage on each register. This is better than a visual inspection because sometimes the leaks can occur in areas not easily visible or even in accessible areas and the numbers don’t lie, if you have low ductwork leakage then it’s obvious that you can save money by not doing duct sealing. You never know until you test.
A thermal camera scan is a powerful visual tool that is better than a laser temperature gun because you can see a larger picture with the thermal camera. It’s a good DIY tool to go around your home and measure for hot spots by seeing an increase in temperature readings but it’s a painstaking effort scan the entire home and most DIYer’s don’t know the hot spots to look for like kneewalls, air barriers and duct chases.
Our energy auditors are experts in attic inspections whereas most homeowners may only go in their attics twice a year and don’t know what they are looking for. We take airflow measures to check the proper duct sizes, check that your insulation is installed correctly (then measure the depth), check for code violations in the furnace flues and drain lines, check for air barriers, proper attic ventilation, ductwork design and layout. We know how to look at the home-as-a-system of interconnected parts and can help recommend priority upgrades over gimmick energy saving products (KVAR, solar attic fans and TCM radiant barrier).
We get many calls at Green ID because our customers notice constant dust in their homes, dust on their countertops, dressers, window sills and dust streaks around the HVAC registers. I've heard many times from homeowners that they have neighbors with the same house layout but they have much more dust than anyone else on the block. Dust can be from many reasons that vary with each home.
Some reasons we found during our energy audits for excessive dust in homes are below.
HVAC contractors have stopped using metal ductwork as their default duct material since the 1980s. The default ducts you’ll see in homes now is flexible ductwork, but that doesn’t mean that it’s a better for airflow. This post will compare metal ductwork with flexible ductwork and help you decide on which is better for your home.
Metal Ductwork Types
Metal ductwork comes in two types, rectangular sheet metal and round rigid ductwork. Rectangular sheet metal comes in 3-4’ sections and is held together with S cleats and drives. Ranch style homes that have registers above the bedroom doorways and a dropped 8’ ceiling in the hallway have this type of ductwork.
The rectangular sheet metal ducts are nailed into the framing of the house and impossible to take out without removing the ceiling as well. Homes built in the 1970s-80s have this ductwork type delivering the conditioned air from a central heating and cooling system but also from an evaporative cooler.
Rectangular sheet metal ductwork are great for airflow because the ducts are oversized to accommodate the large amount of air delivered from the swamp cooler. Studies have shown that metal ductwork is not necessarily better than flexible ductwork but the advantage of metal ductwork is that is hard to install wrong. Metal ductwork does not kink as easily as its flexible ductwork counterpart. As I’ll discuss later, flexible ductwork is not only easy to install, it’s also easy to install wrong with kinks over trusses or electrical wires, too much length, or hard 90 degree bends.
The second type of metal ductwork is round rigid metal ductwork. Round metal ductwork can either be spiral duct, which comes in one 10’ section of different sizes and is not insulated. This is a great look for restaurants, commercial buildings or even homes that want an industrial look. Insulating spiral ductwork more than doubles the price because the insulation is cut and glued between each of the spiral ribs. For this reason uninsulated spiral ductwork is mostly used in conditioned space. The second type of round rigid ductwork is KD pipe which is snapped together at a seem and comes in 3’, 4’ or 5’ sections depending on the size. This ductwork also comes uninsulated and can easily come apart if not mechanically fastened together and can be deformed and crushed if walked on (yes, I have seen cable guys, HVAC technicians, insulation installers, electricians all crushed this kind ductwork and left as a casuality of their work). The airflow is slightly better in KD pipe than in compressed flexible ductwork, but if the flexible ductwork is pulled tightly the airflow will be the same.
Why Metal Ductwork Is Bad
The downsides of metal ductwork is that it rusts and it leaks. With new homes the rust isn’t much of an issue but with homes that also had a swamp cooler installed with metal ductwork, there’s a high chance of rusting already occurring in the metal ductwork. I’ve seen rectangular metal ductwork rusted so bad that large gaps have been made and cold air pouring into the attic in the summertime.
Because metal ductwork only comes in 3 foot sections (compared to a 25 foot bag of flex duct), there are plenty of joints and places where air can escape. In addition, if the metal ductwork was never sealed before the drywall went up when the house was being built, the bottom half of the ductwork becomes inaccessible to seal by hand and requires a more expensive Aeroseal process to seal properly.
The alternative to metal ductwork, and the most commonly used type of ductwork today is flexible ductwork. Flexible ductwork is made from 3 different sections, a outer reflective sleeve, an insulation layer and a vinyl plastic inner liner with a metal spiral rib holding it’s shape. Flexible ductwork was first used in Arizona homes in the 1980’s with a clear inner liner. This type of ductwork has since been outlawed as it deteriorates and becomes so brittle it will crack and split open with the air pressure. When changing your air filters, if you see a clear inner liner at the return duct, you know you have this type of ductwork.
Flexible ductwork must be installed properly to get the right amount of airflow to each room and a poor installation can severely affect airflow and comfort in your home. This means no kinks, using 90 degree elbows at all ceiling cans and the ductwork is pulled tight with minimal slack to minimize friction resistance.
Can I Install Metal Ductwork On An Existing Home?
Yes it is possible to change out the flex ductwork in your home to all metal ductwork but it is costly. Metal duct installers used to have a name, tin-knockers, because of the skill required to measure, fabricate and install the ductwork was a skill. Unfortunately today, there is no name for those of us that install flexible ductwork. The fact is anyone can install flexible ductwork, so anyone and everyone does. With little to no training, installation best practices go out the window, which is one of the main reasons why I’m not worried about finding work for my lifetime but I digress.
Installing metal ductwork in an existing home is expensive for two reasons.
1. Material Cost Is High
I don’t know what prices for tin were in the 1970s but to purchase metal today is pricey. Consider that one bag of 16” x 25’, R8 insulated ductwork cost around $90. A 4’ section of KD pipe costs $23 or $138 for 6 sections and that still has to be put together and does not include wrapping the pipe in insulation. Spiral metal ductwork costs $51 for a 10’ stick, or $102 for 20’ and again it is uninsulated and difficult if not impossible to fit a 10’ section in an attic hatch and through the maze of trusses. Insulating the ductwork increases the spiral pipe to $200 for 20’.
2. Installing Is A Laborious Process
Because the attic can only be access from a 2’x3’ access in the attic (not to mention all the roof trusses one has to navigate) a 10’ section of ductwork can be impossible to move to where it needs to go. Easier attics to get around have higher pitches and plenty of space to walk around but even then, it’s likely a two man task to just set the ductwork in place. Once set, the ducts needs to be secured, sealed and then wrapped in insulation. The right elbows and bends need to be in place to terminate the ducts into the ceiling cans and registers and all that labor can add up quickly. It can be done but but you have to ask yourself if a small improvement in airflow with metal ductwork is worth double the cost of installation verses decently install flexible ductwork.
What’s The Difference Between Metal Ductwork And Flexible Ductwork?
Converting round rigid metal ductwork to flexible ductwork all depends on how the flexible ductwork is installed. A 4% compression is a generally accepted practice. To get less than 1% compression would risk the duct being pulled so tight it would disconnect from one end. At a 4% compression, you loose about 1”-2” of duct diameter going from flexible ductwork to round rigid ductwork. That is, a 6” fleixble duct will deliver the same amount of airflow as a 5” KD pipe duct.
Can I Install Metal Ductwork On A New Home?
What about installing metal ductwork on a newly constructed home? Metal ductwork can better for airflow and the installers don’t have to deal with the space restrictions that come with existing homes, so it would make sense that the cost decreases also. Well, not necessarily because insulated metal ductwork can be twice or more the cost of flexible ductwork. If you are willing to pay double the costs of flexible ductwork and have the piece of mind that all the airflow coming out of your unit is going in your home, than metal ductwork is the way to go on a newly constructed home.
What’s Wrong With Flexible Ductwork?
Nothing is wrong with flexible ductwork when installed correctly. It is on par with sheet metal ductwork for airflow. What’s wrong with flexible ductwork is that it’s so easy to install wrong. What could go wrong with flexible ductwork installation? Here is a short list.
What’s Good About Flexible Ductwork?
There are good attributes to flexible ducts that in my opinion outweigh the bad. We make our case below.
If flexible ductwork is installed correctly, the airflow will be the same or better than a metal ductwork. It’s all in the installation. The advantage of metal ductwork is that you are taking less of a chance of the ductwork being installed wrong than with flexible ductwork. It’s harder to install metal ductwork wrong than it is flexible ductwork. If you can find an installer than follows the best flexible ductwork installation (like Green ID), then there’s no difference between airflow from flexible ductwork compared to metal ductwork. The cost will be significantly less with flexible ductwork compared to sheet metal ductwork.
Loss In Flexible Ductwork Studies https://www.osti.gov/servlets/purl/836654
Making green upgrades to your home can majorly increase your comfort. Unfortunately, comfort and quick paybacks don’t always go hand in hand. Upgrades like window replacements, garage insulation and increasing insulation levels to assure they’re up to the R-38 standard, are all upgrades where the most cost effective solution may not align with your lifestyle conditions. For example, replacing single pane windows in good condition is not cost-effective but the price paid for one south or west-facing window may well be worth the cost if it cools down a hot office or reduces traffic noise at night. It’s clear that in some situations the lifestyle conditions may outweigh the cost or payback of upgrades.
Insulation changes are another popular upgrade that homeowners choose to make. Adding insulation can often times give homeowners greater temperature control in their home but not every home is the same in terms of insulation. If a home has already met a R-38 Energy Star standard adding more may still save you money on utilities but only by a small margin opposed to adding insulation to an aged home where the insulation has sank. In the later example the upgrade would most likely save the home owners much more on their utility bills. Often the more important issue is finding out how the insulation installed. A 5% defect in the installation will cut the R-value (its effectiveness) by 50%.
All considerations for upgrades can be discussed with an energy auditor who will give you their professional and unbiased opinion of the most cost effective upgrades you can be making in your home. It’s important to get a professional opinion when making investments that could save you money and increase your comfort.
It can be shocking to find that your air conditioner can’t keep up in the summertime and sometimes even rises in temperature during the hottest part of the day. It can be hard to tell if you’re AC system is running right, if your AC is broken, or if you have another issue with duct leakage or insulation. In this post will explain what can be causing your air conditioner to not cool the house properly even if you have a new, high-efficiency AC system.
If you’re like many of us in Phoenix Arizona we have a low humidity, dry heat for 10 months out of the year. But every July and August comes our monsoon season which brings the occasional rain and more importantly humidity into Phoenix. If you’re finding that your air conditioner cannot cool the house until the middle of the night when it’s the coolest and sometimes it even rises when you have the temperature set low but it works fine the other 10 months out of the year I’ll explain the possibilities in this post.
Common Misconceptions About New Air Conditioners
Some common misconceptions about air conditioners are that higher efficiency units are going to give you more air or cool the house better. It’s true that the high-efficiency units cost less to operate and can lower your energy bills but what’s not true is that a new air conditioner will give you more air or cool your home better. What many air-conditioning companies get wrong is that:
The Truth About New Air Conditioning Systems.. the Dirty Little Secret About New Air-Conditioning Systems
Every manufacturer has multiple options for new AC systems and each option has different capacities. This is important because you may currently have a true 5 ton, or 60,000 BTU air conditioner now but with manufacturers cutting cost they will offer distributors 5 ton systems that it only give 55,000 BTUs of capacity which is almost a half a ton lower than what you have now currently. This is something that you may never know for your sales rep may not know because this is the only unit that the company offers. It may also be the only unit that fits in your attic space or closet. A good air conditioning installer will not compromise the capacity of the air conditioner because we know that if you’re used to having 60,000 BTUs of air delivered and we put a new system and that only delivers 90% of that we’re likely to have problems in callbacks.
Problems With Existing Air Conditioners That Make It Struggle To Keep Up
Undersized System. Although we advocate a properly sized AC unit, I’ve seen more and more builders on new construction homes install the wrong size AC unit or even undersize the AC system. While this can happen on an existing home, I’ve seen it more often on new homes. Builders must use a Manual J calculation to size the AC system correctly but that calculation highly depends on the inputs and assumptions the AC contractor uses. If they put you will only cool your home to 78 degrees and you want it at 76 degrees, the AC unit is going to struggle to keep up. If the correct orientation of the house is not chosen, you may have more heat gain than the AC system is designed for. I have seen both of these issues happen in brand new homes.
Restriction Causing Poor Airflow. A restriction can be from a dirty filter, clogged filter dryer, dirty condenser coil or dirty evaporator coil. Each of these problems will cause lower than normal airflow and poor AC performance. The easiest thing you can do is to change your AC filters every month or two, even if the recommended changing time is three months. If you notice your filter dirty, it’s time to change it.
Freon Leak. If your AC system keeps needing a recharge of freon every year, there are several ways to identify and find a freon leak. A dye can be added to help identify a freon leak which glows under a UV light, a nitrogen pressure test can be used to hear and feel where the leak is occurring and the easiest method of finding a freon leak is having an experienced technician knowing the most common locations for leaks and performing a visual inspection. Letting a freon leak happen can damage the compressor overtime and shorten the life of the system.
Freon Overcharging or Contamination. If you have had a freon leak where an A/C company had to add freon and now you’re having cooling issues, you’re system may have been overcharged. This is a common mistake and can be hard to diagnose for the untrained technician. Too much freon can cause liquid to flood the coil and damage the compressor. A contaminated freon charge will cause temperatures to flucate and may also damage the compressor.
Why Your Air Conditioner Won’t Cool The House
If your air conditioner finally works and seems to lower the temperature during the middle of the night but struggles and actually rises during the daytime then you’re likely having issues with humidity during the monsoon season. The humidity will make an air conditioner work much harder and can struggle to keep up. This is more and more common with systems that are slightly undersized or even sized with razor thin margins as is becoming more and more popular now. In the past contractors would purposely oversize a system but that led to a number of problems including high energy bills, more ware on the compressors from short cycling, and comfort issues.
However, and I hate to say this the only thing good about an oversize system in Phoenix is doing the monsoon season it is better at removing the humidity and keep in the house at a comfortable temperature more consistently then if your system is undersized or on the borderline. The inconvenient truth is that you may have to suffer during the two months out of the monsoon season while your air conditioner struggles to keep up and there may be absolutely nothing wrong with your system, it may be charged correctly and all the components operating within specifications.
Why The Second Floor Is Hotter Than Your First Floor
If you have noticed the rooms on your second floor are much hotter than the first floor we have dedicated an entire blog post to shed light on the causes and potential fixes for the uneven temperatures.
The main causes have less to do with your air conditioner’s performance and more to do with the ductwork, insulation and airflow. This is where an energy audit will really shed light on what the causes are and offer the best solutions compared to having an AC contractor tell you to add another return or that you need a new unit, a window person try to sell you all new windows and an insulation contractor perform and “blow-and-go”.
How To Stretch Out Your Air Conditioner's Performance
If you're stuck with you got, there are some ways to give your AC system a nudge in the right direction and the good news is that it may be enough to push you over the top and finally fix your AC system from not keeping up with the thermostat settings.
1. Sealing The Ductwork To Make Your Air Conditioner Perform Better
In Phoenix, sealing your ductwork is the most cost effective upgrade you can do and one of the most common problems we find in homes 15 years or older. SRP estimates that Phoenix homes loose about 20% of their air into the attic through duct leaks. SRP even offers a good rebate to seal the leaks up because they know it’s a cost effective upgrade. Imagine getting 20% more air into your home just by sealing the duct leaks, it’s pretty significant. Have Green ID perform a duct leakage test and energy audit on your home today to find out where you’re leaks are coming from and qualify your home for the SRP duct sealing rebate.
2. Size Your Ductwork Right To Make Your Air Conditioner Perform Better
Along with sealing the ductwork, returns that are too small is the next lower hanging fruit upgrade that will help your air conditioner perform better. I wrote an article about Why Phoenix Is Called the Land Of No Return to help get contractors to start upsizing and adding second returns in homes.
What happens is homes is a 4 ton air conditioner is installed for example, but the ductwork is only sized to handler 3 tons of air. Now your 4 ton A/C system is acting like a 3 ton system but you’re paying the energy costs for the full 4 tons.
3. Add More Insulation To Make Your Air Conditioner Perform Better
If you have a block wall home, consider injecting a closed cell spray foam in the sun struck block walls to reduce the heat gain on those walls. Block walls have no insulation in them, making them radiate heat well into the night in the summer.
When it comes to attic insulation, even new homes are underinsulated. Adding more insulation to the attic can help keep the cool air in your home much longer. If you have fiberglass batt insulation on a home built in the 1990’s, your insulation will be like there’s almost nothing up there because it’s likely installed wrong.
4. Use 90 % Shade Screens To Block Windows That Get More Than Two Hours Of Direct Sunlight.
Don’t be surprised that windows get more heat gain coming into your home than from the attic in Phoenix! Using shade screens is more cost effective and effective approach than replacing old leaky windows. A common misconception is that leaky windows are the cause of high energy bills and that replacing old windows will fix comfort issues. This couldn’t be further from the truth. Save yourself thousands and install shade screens before replacing old windows. On a side note, we do recommend replacing windows for ascetics or sound proofing but just be cautious if you are replacing windows for energy savings and comfort that we have seen many disappointed customers over the years.
These energy efficiency upgrades above are more cost effective and give you a bigger bang for your buck than doing a full HVAC replacement prematurely. While a new AC system may have some benefits and offer peace of mind, it’s not always the best solution to help your AC cool your home better.
During the Covid lockdown, although I can't blame it all on Covid, I was deep in a Youtube wormhole and came across videos of a guy that upcycled and reused common items for creative purposes. We've all seen those stories, whether it be duct tape, Popsicle sticks or paper clips. My personal favorite was making a bow and arrow out of a paper clip and rubber band. Well how about actually putting some of those ideas to work and actually saving you money.
The good news is that there are things you can do to lower that utility bill on any budget. There are simple things you can do for no cost and upgrades, that make an impact, can be done for under $1000.
No Cost Energy Saving Upgrades
$100 Energy Saving Upgrades
$500 Energy Saving Upgrades
$1000 Energy Saving Upgrades
Before spending any money, it is a good idea to get a home energy audit. Green ID is a qualified, licensed and bonded HVAC contractor and charges only $99 and is well worth the money. A good audit should be more than just a visual examination and should check static pressure, room pressure, condition of the duct work, adequacy of return and supply registers, and as assessment of the air conditioning unit. Audit results will help you determine where the money is best spent and give you some low cost/ no cost ideas to reduce your energy bills and make your home more comfortable.
The Main Cause Of Loud Noises When The AC System Is Running
I remember sitting to watch TV after dinner during the summer time and finding myself unable to hear the TV only when the AC system kicked on. My AC system was so loud it sounded like I was sitting in a wind tunnel and every time it came on I had to turn the TV volume higher, then when the AC shut off, the TV was too loud and I'd turn the volume back down. I remember not thinking anything about it at the time, only that it was a slightly annoying habit. Little did I know what was causing that wind tunnel like noise was actually hurting my AC system.
It was only year later when I started Green ID and performing energy audits and retrofits that I realized what was actually causing this to happen was an undersized return. Undersized returns plague the Phoenix market in homes of all ages and all types of HVAC systems. HVAC contractors and installers never seemed to get this right and the fact that Arizona homes are typically built with only one return per AC unit, this problem is still going on to this day.
Why Is An Undersized Return Hurting The AC Unit?
If you've ever been short of breath, had asthma or felt winded after an intense workout you know what it feels like to be starved for air... it seems like you can't get enough air into your lungs. That's what happens all the time when the AC system has too small of a return installed. That loud sound I was hearing was actually my AC system wheezing for air, it was literally trying to inhale more air than could fit in the ductwork. This makes the AC system work a lot harder, reduces it's capacity and creates a loud, wind-tunnel like noise at the grill.
How Do You Know What Size Return Is Good Enough?
We use a rule of thumb per the table below for the return duct size however the problem can often lie in other places like the elbow type, return air can, filter, grill, kinks in the ductwork and plenum size. A simple check you can do yourself is with the air or heat on, remove the grill and see if the noise is reduced. Then remove the filter and see how much that improves the noise. The solution to undersized returns is to make the return size larger. We can do this by adding a larger return, a second return, installing a return plenum or changing a twist elbow to a side by side elbow. Having a comprehensive energy audit on the home will present the best options because contrary to what your HVAC contractor may believe, it's not always as simple as adding a second return.
Return Size Chart
5 ton should have at least a 22" return
4 ton should have at least a 20" return
3 ton should have at least a 18" return
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