What should I ask my HVAC contractor when getting AC bids?

What should you look for in an HVAC contractor in Phoenix?  Getting your heating and cooling system replaced is a very important day and the right preparation on your part can add years of additional life to your unit with minimal repairs and great Air conditioner savings along the way.  Get it wrong, and your air conditioner and heater will be plagued with emergency AC repairs, loud AC fan noises, bad capacitors and fan motors and an early death.  Unfortunately, according to the DOE more than half of new systems in U.S. homes do not perform to their rated efficiency as a result of improper installation. In fact, improper installation can reduce performance by as much as 30%. This not only affects your utility bills, but can lead to a variety of comfort problems, including insufficient cooling, dust from leaking ductwork, and poor air distribution.  At Green ID, we tell our customers it doesn’t matter what manufacturer you go with for your HVAC system, the most important thing is how it’s installed that first day.  Here is a reference guide to help choose the right heating and cooling contractor.

​Ask the following questions to each contractor:

1. What best practices does your company follow during my installation?
 
This single question posed to AC contractors can reveal a lot on how the company performs their installations.  You can trust and like your sales rep but if they don’t know or you get a blank stare as a initial response, you’re better off finding a contractor who is a little less polished but knows their installation crews.
 
Experienced air conditioning contractors are good because they know where the hiccups occur during an air conditioner install and how to avoid them and they know what the most common call backs are and how to avoid them. Most of the time doing the right thing requires a little extra effort on their part during the AC install. For most AC contractors this is not the standard way of doing their installs and just like learning how to swing a golf club the correct way verses the easy way, it takes them out of their comfort zone and most would rather just skip doing the extra effort verses spending a little more time, effort and materials to do it right. 
 
You definitely want to hear an air conditioning contractor tell you they do the following:
 
a. Charge the system with the correct amount of refrigerant after installation. This is not factory settings as every system comes with refrigerant already charged it. Many contractors just leave the factory charge and do not bother adding any more or measuring to find out how much more is needed and this is a big problem. If the distance from your outside condenser to the inside air handler is more than 15 feet, your AC contractor should be adding more refrigerant as the manufacturers only add enough refrigerant for 15 feet of refrigerant line.
 
b. Size the unit according to what your home needs, not based on the square footage of the house alone. This requires a Manual J calculation on the house so you should see your contractor measuring your windows and actually going in your attic to measure the insulation. 
 
c. For package roof units, you want a side by side elbow, not a down draft and not a over-under aka twist elbow. This is a major no no that most AC contractors are guilty of not following. Down draft and over-under elbows are cheaper and easier to install and require less labor and materials but are NOT best for your energy bills, comfort and the life of your system. If your AC contractor is really stuck in their ways or really lazy, they will make up excuses on why down draft and over-under elbows are OK to install, they may even believe what they are saying is true but hold firm in your affirmation that you want a side by side elbow. Here's our list of reasons why a side by side elbow is better on package HVAC units in Phoenix.
 
d. Supply and return plenums
A plenum is a transition between the ductwork and the unit. If your furnace or air handler is in the attic like most are in Phoenix, the plenum is likely a sheet metal box that has flex duct connecting into it and the other side is attached to the furnace. If your furnace or air handler is in the garage or closet, the return plenum is the framed box that it sits on and the supply plenum is the sheet metal on top. Plenums are important for proper airflow, allowing the unit to breath and mix air in the box before it hits the evaporator coils. They are not always included in the cost of an AC but should be. It is extra work to install them but every home should have them.
 
e. There are several other must-haves when requesting specifics during air conditioner bids but the list above are the basics to start you on the right foot. I would make sure all these things were done on my own home and you should too.

2. How will you determine the maximum system size that can be installed with my existing ductwork?
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I love this question because it immediately separates the true players from the fakes.  It is a variant of the question of system sizing for the house and asking if the contractor performs a Manual J load calculation to verify the size of the unit.  Here you are making sure your ductwork is going to be properly sized for the unit, which is just as important as matching the size of the unit correct to the house specifications (windows, insulation, duct leakage, sq ft, air leakage, etc).  Having a 5 ton HVAC system with ductwork that can only handle 4 tons of air is a big problem and we see it all the time.  It causes the HVAC system to work harder than it needs to, shortening the life of it’s components, comfort issues with hot and cold rooms, weak airflow, exaggerates ductwork leakage, and causes noisy systems.

The correct answer would be to measure the static pressure of the unit to see how well the air is moving in the and out of the ductwork before a new unit is installed.  This will require your contractor to go in the attic (if your HVAC unit is located there) to measure and if you never see them go in the attic, you know that your static pressure was never measured.  It is possible in many cases to increase the size of the ductwork to handle more airflow and that will be up to your HVAC company to determine.
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To lower your energy bills, make your home more comfortable with less dust, you cannot rely on just changing the air conditioner and heater alone.  Your contractor needs to consider the ductwork as well… and if they are really on their game they are going to talk about your insulation as well.  Duct leaks and poor airflow to rooms are the major cause of comfort issues… it’s not having a dinosaur HVAC system.  A new variable speed HVAC system is not a one-stop-shop to fixing those problems although some HVAC contractors may make it seem that way, resist the temptation to look at just the box.

3. Do you recommend and how much is it to install new refrigerant lines rather than reusing existing lines?
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The answer you are looking for is “yes”, when switching from the old outlawed refrigerant R22 to the more environmentally friendly R410, we always recommend installing new refrigerant lines. The old R22 refrigerant is not compatible with the new R410 refrigerant, they don’t mix well together and you can ruin your compressor if the old R22 is not cleaned out of the refrigerant lines.  Does it increase the cost?  Yes, it will add to the cost but you are taking better care of your new unit now to have a worry-free system in the future.  Changing out your existing refrigerant lines is labor intensive and copper lines are not cheap, but I like this question because it gives you an idea where in the ballpark this AC company falls in terms of best practice knowledge and actually caring for the quality of work or if they are just going for the sale.  

4. Will you help me install my programmable thermostat?

It’s easy for HVAC installers to get used to just doing the installation routine without much customer interaction.  However for a complicated AC system that costs thousands of dollars, it’s helpful to have a little explanation of your new unit and getting acquainted with all its nuisances soon after it’s up and running.  This starts with the thermostat, the only interaction you’ll probably ever have with the entire system.  Programmable thermostats can save money on your energy bills by setting the temperature up while you are away in the summer, similar to turning the lights off when you are not in the room.  The smart thermostats of today can sense when you are away automatically raise the temperature up in an energy saving mode that you don’t have to think about.  However, some thermostats are pretty complicated to navigate, change the settings, set up the wi fi and learn the functionalities.  It can be like programming your VCR or the old digital watches, something we can put our attention to maybe once to try to program, then we just give up the rest of the year and just live with the factory settings the same as when we took it out of the box.  Ask your AC company to agree to help you install and set up your programmable thermostat for easy additional comfort and savings.

5. How do you fix a hot room?

Whether you have a room that’s different temperatures than the rest of the house or not, this questions can tell you if your heating and cooling company is more on a cookie cutter path or takes a more customized approach.  More and more heating and air conditioning contractors are defaulting to installing a new return in a hot room to help air circulate out of the room.  It is true that you can never have enough returns in your home but it all depends on the best practices of the company.  In our experience adding a return an help make a room more comfortable, but it’s subtle and won’t leave you feeling entirely satisfied.  We have lots of feedback from our customers who had only returns installed, only additional supplies, and both additional supplies and returns and the results are not promising.
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You can read our post on why rooms get so hot above a garage here to get an idea what truly causes comfort issues and the correct way to address them, but it is NOT by adding a return to a room (you’re welcome HVAC contractors).

6. When installing my ductwork connections, will you seal at all the duct seems first?
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Proper heating and air conditioning installation has so much more to do with the ductwork than it HVAC contractors give it credit for.  Again this question hints at a whole home approach to air conditioning installation.  AC contractors that just consider the unit change out are leaving their customers short and are asking for a life time of AC problems.  Early capacitor failures, bad fan motors and pitted contactors are signs that something else is going on in the attic outside of the actually unit that are causing early failure.  Other signs the airflow and ductwork needs to be properly inspected are rooms that are different temperatures than the rest of the house, excessive dust and high energy bills.  An air conditioning company may claim that this new high efficiency SEER 16 system is going to fix comfort and dust concerns but putting a high end AC unit on a badly designed duct system is like driving a Prius with a hole in the gas tank.  It’s best to consider a whole home approach when replacing your air conditioner and start with a certified energy audit.

7. Will you test to confirm that duct leakage does not exceed recommended levels?

Testing for airflow and duct leaking is the only way to be sure if the work was done right.  That test can be done with a blower door or duct blaster and is pictured here

Aerosealing is an effective way at sealing small holes in the ductwork but it will not seal anything greater than 1/8th of n inch.  In many older homes, the ducts have a hole greater than an 1/8th of an inch so a manual seal is better suited and is what we at Green ID prefer because we apply our sealant on thicker and it our product has a longer lifespan than Aeroseal.  Read more about Aersoealing and the bad wrap is has been getting here.
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8. Will you confirm proper levels of refrigerant and airflow across the coil?

This last question is important because a typical HVAC contractor will say that the units come factory charged and that is enough the typical house.  What they don’t tell you is that every manufacturer is different and many AC manufacturers have been chronically light on their factory refrigerant charge.  This means that, yes, after every install the refrigerant levels should be measured and the proper amount needs to be weighed in to ensure the correct amount is put in the system from Day 1.  A rule of thumb is if the refrigerant lines are longer than 15 feet, that is 15 feet from your outside condenser to the air handler in the attic, more refrigerant should be added. 

Measuring airflow across the coil is important because you want to be sure you are getting the correct amount of airflow into the home.  Air conditioning companies need to measure that all the air into the return is existing through the supplies and that it is the correct amount of airflow for the size of the unit.  Most HVAC contractors will just install the box and forget about anything outside of it to the owners determent. 

When you purchase a new heating and cooling system, you expect high performance. Not all Phoenix HVAC contractors are the same.  Ask the AC contractors bidding for your business if they follow ACCA Best Practice Guidelines or ENERGY STAR® Quality Installation Guidelines (www.energystar.gov/qispec) to ensure that you are not buying just a piece of equipment but a properly installed heating and cooling system that provides comfort and efficiency.