I don’t mean to come across as being too blunt, and in fact there are many subjects like ductwork design and installation that I am much more passionate about and should raise arms about the one industry that did it all wrong for years without oversight… but I don’t know how to say it any other way. For homeowners that are doing everything they can to reduce their energy bills, I often get questioned during home energy audits or installations, “what do you think about tankless water heaters?”
There are some considerations you need to weigh. First of all, gas water heaters don’t cost very much to begin with, and switching one out to an electric water heater will actually cost you more money each year to run. However, a good reason to switch from a gas to electric water heater would be if you have a dryer in the same room, your water heater is inside your house, or for other health and safety reasons to keep carbon monoxide out or prevent it from back drafting down your flue.
However, you can expect to see savings using a gas tankless water heater, but even just the initial installation is costly, ranging in the $2000’s. Also, one thing I would definitely have checked after the installation of a tankless water heater is for gas leaks. On homes, 9 out of 10 gas tankless water heaters we have checked during our SRP energy audits, we have found gas leaks. I don’t think this is coincidence, so please have this checked.
Electric water heater users are in luck, they have tanks that at a federal minimum energy factor of 0.90, which is a very high rating (gas water heaters have efficiency factors of 0.59 for standard water heater tanks and 0.95 for tankless water heaters). Because of the low energy loss (the heating element is surrounded by the water it heats), electric water heater efficiencies can’t get much better with electric tankless water heaters (0.89 - 0.99 efficiency factor). Surprisingly, electric water heaters use a lot of energy when they are on, so much in fact, that you may not save much money at all. The whole idea of a tankless water heater is to only turn on when you need the water, or on-demand. Manufacturer’s claim for electric tankless water heaters savings between 20% - 50% annual reduce in water heating costs. Gas tankless water heaters are in at 20%-25% annual reduction in water heating costs. In an Energy Star Report, it is humorous that they noted the same savings can be achieved by simply wrapping a water heater blanket around the tank and turning down the temperature setpoint.
When electric tankless water heaters are recommended
Wait, didn’t I just say electric tankless water heaters are a bad idea? Well, there are some cases when it would be acceptable to install one, such as for additions or fixtures very far away from the main water heater. Or in vacation homes with standby energy loss can kill your energy bills. I once did an energy audit for a cabin on Strawberry Hill in Strawberry, AZ, and each cabin had a small electric water heater for each unit. Standby energy loss accounts for up to 20% of water heating costs whether water is drawn from it or not. If they replaced each of their water heaters with tankless water heaters, it could add up to significant savings.
Consumer Report Review
Before the SRP home energy audit program, was their long standing shade screen program. Unlike SRP solar rebates, SRP shade screen rebates have increased over time, to $0.80 a sq ft. Only south, west and east facing windows will qualify for rebates and screens must be either 80% or 90% sun blockage. Unfortunately retractable sun screens do not qualify for the rebate nor do shaded windows. Homeowners should also be aware of their window warranties if new window vinyl windows were installed, often shade screens need to be clipped to the stucco rather than the window frame.
There are two ways to qualify for the rebates. The first is to have an SRP energy audit performed on your home for $99. The home energy audit will pressurize the house to identify air and duct leakage and the auditor will perform visual inspections and make recommendations on the home’s major appliances and energy users, attic and insulation condition and perform a thermal camera imaging of the home. By performing the energy audit you will qualify for not only shade screen rebates, but also rebates for air sealing, ductwork sealing, and adding more insulation to your attic (if your auditor determines you need these items). Your auditor will process the rebates on your behalf and perform a post inspection test to ensure the work was done to SRP and Energy Star specifications.
The second way to take advantage of the shade screen rebates is to have a screen company approved by SRP out to estimate and install your windows separately. There is a separate rebate form, that the installing contractor will sign and leave with the homeowner to mail into SRP. The SRP shade screen form can be found below.
For more information on the shade screen program see SRP’s link below.
You have probably seen APS and SRP promote switching your utility plan to a time-of-use plan if you are not currently a part of one. It is painful to almost double your current rate (up to $0.21 a kWh compared to $0.11 a kWh for off-peak) during on-peak hours so it can save on your energy bills but you have to manage it correctly. I have switched and switched back and as a Phoenix home energy auditor I can recommend some tips to help you make an informed decision.
For the time-of-use plans, I have found them beneficial only if:
1. You leave home for work on a regular schedule, especially during the summer when daytime rates are higher.
2. OR you install a major high efficiency upgrade like a variable speed pool pump or water heater timer.
3. OR if can be diligent, and to some degree, put up with, managing your energy usage during the day. That means precooling your home to 72 degrees an hour before on-peak time starts, then bumping up the thermostat until 6 pm and off-peak begins. It also means to a lesser degree doing laundry (the dryer more so than the washer) and running the dishwasher at night... but don't worry if you don't follow this one so closely, the most important energy user is your heating and cooling system.
During the fall, winter and spring when APS rates are lower, the savings benefit will not be as great and the effort you put into trying to manage your usage I have found, not to be worth the small savings if not done on a regular basis. So if you are not on a regular work schedule where you leave the house in the morning then return at night, it is difficult to realize energy savings.
As a side note you are allowed by SRP to switch your plan twice without penalty, so you could try a time-of-use plan and see if you can manage the thermostats where you hardly notice the temperature setback, then if you find you don't like it you can switch back to a normal plan anytime (i.e. 1 day later) at no cost. If you find you want to try a time-of-use plan again though, then SRP will let you but if you want to go back, you will have to wait a several months or pay a penalty fee.
The setback range will vary depending if you ask an HVAC contractor or APS or SRP, but 10% of where your thermostat is set now is a good rule of thumb. So if you are at 78 degrees, an 8 degree setback is good. An important consideration is if your AC system(s) are sized correctly for your house. If it is sized properly they should be able to handle cooling the house back down within 1 hr without a problem. If they were oversized, it would be faster to cool your home but you would be wasting energy from short cycling the rest of the day when you were at a steady 78 degrees. Short cycling is wasteful and uncomfortable because an oversized AC system will reach it’s thermostat set point quickly, so the AC runs for only 5 minutes then shuts off. This causes temperature fluctuations between hot and cold, wastes energy because of the shut up of the motors requires an energy jump-start and uses more energy over the long run. If the AC units were undersized, I would only set it back a couple of degrees because it would take longer for the house to cool. A perfectly sized system will run continuously for 1 hour during the hottest part of the day. I always recommend trying it and adjusting as you go because we can do heat load calculations and theory all day but until you apply it to your lifestyle, home and duct leakage we never truly know how the system will react.
A variable speed pool pump has 8 different settings available to help homeowners take full advantage of APS and SRP's time-of-use plans. SRP time-of-use has on-peak hours from 1 pm - 9 pm during the summer and 5 am - 9 am and 5 pm - 9 pm during the winter. With a variable speed pool pump you want to turn your pool over only once to maintain a clean pool, so you can program different speed settings and times to run the pump that coordinate with your pool's volume and the off-peak hours.
You can learn more about thermostat set points and what SRP and Energy Star have to say at the link below.
You may also want to try a water heater timer, where the water heater is turned on during the night and off during the day, and see if you can match it to you lifestyles. Ideally, you won't notice any change and your recharge on the water heater is completely in the background. It is a good idea to save some more money on your utility bills because the tanks are constantly turning themselves on to keep the water at 130-140 degrees, even when you are not at home.
Here are some important links:
APS Time of Use Rate Plan
Having a teenage daughter and a day-time nanny makes it hard for me to take advantage of the time-of-use programs but I do encourage it for our clients. Good luck and let us know if you have any questions.
Why should you move your washer and dryer to the garage or outside. Helping APS and SRP customers save energy.
If you are like me, your garage is hard pressed for some extra space. With all my kid’s stuff, holiday decorations, extra boxes and camping gear our storage shelves are packed… but here is a good reason why it’s worth the effort to create some space and relocate your dryer to the garage.
Dryers are work against your AC and furnaces because they exhaust your conditioned air every time they are run. Next time you take out the garage, take a look up and at your walls and you will see your dryer exhaust vent. Remember that great smell of doing laundry? That’s from your dryer exhaust fan. They are one of the highest exhausting appliances you have depending on how big your kitchen exhaust fan is. Dryer will pull anywhere from 100 CFM on the low side to 230 CFM on the high side. This can be potentially a health and safety hazard if you have an attached garage or gas appliances for potential backdraft of carbon monoxide and something your energy auditor will inspect.
An air conditioner is typically sized for 400 sq ft per ton. That means if you have a 1600 sq ft home, your AC should be around 4 tons. However, when the dryer is running, it is undermining your AC system by almost half a ton. So that 4 ton unit actually becomes a 3.5 ton unit with the dryer running.
Dryers typically run off of 240 volts and have a special outlet dedicated just to the dryer. It is best to hire a qualified electrician to add the proper voltage to the garage or outside.
For gas models, be sure the gas line is shut off when you disconnect the dryer and talk to your plumber about tapping into your barbeque gas line for the dryer or water heater line in the garage.
Here are some DIY steps to help you take the leap and the dryer.
I should also note that not using your dryer at all and buying a clothes line or drying rack will save you even more money and a few hours in the desert sun will dry your clothes without fading them.
The average family washes about 400 loads per year and 2.3 kWh/load. That equates to $92 a year for laundry, not including the air conditioning lost from the exhaust vent.
To find how much energy dryers use, check out the link below.
If you have to run your dryer more than once, read our previous blog on how to troubleshoot it.
You can also calculate your energy savings by switching to an Energy Star appliance by downloading this cool calculator.
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