Many homeowners (and even some HVAC contractors) don't truly understand HVAC equipment efficiency ratings. They think that the higher they are the better. Often times, they think that because they bought a unit with the potential to be highly efficient that it will actually be highly efficient. If it were only that simple.
The train of thought here isn't wrong, however. If you stop there, you could find yourself paying a lot of money for a system that has the potential to be highly efficient when, in fact, it isn't or won't be if not cared for properly.
I want to share with you the things that you, as a homeowner, can do or have done to maintain the highest efficiency performance of your air conditioner and/or heat pump once it's installed. But before I do, let's try to get a better understanding of these efficiency ratings so you can make a wise purchase in the beginning.
I'm not going to get into the nitty gritty science of SEER (Seasonal Energy Efficiency Ratio) ratings and how they are calculated since that in and of itself could take many days of classes and reading a lot of books to fully understand. Instead, I'll stick with what I think is important to you as a homeowner at the time of purchase of a new unit, which is getting what you pay for.
Nearly every air conditioner or heat pump will have (or should have) the words "up to" in its sales literature or perhaps "may vary based on other equipment" on the Energy Guide tag of the unit when referring to its SEER rating. This is part of why I say efficiency is a potential, not a promise.
A 16 SEER condensing unit (the outdoor part of your system) for example means with the right air handler/furnace and evaporator coil, the unit can achieve a 16 SEER rating. However, if you put in that "other" coil because it's a bit cheaper or easier to install on your ductwork and then install the system on your existing 15-year-old furnace (though it may work just fine), you won't likely see that out of your unit regardless of what the salesman or sticker said it could do. Even when all brand new equipment is being installed, if not matched properly, it will never achieve the SEER rating it is capable of.
So how do you, the homeowner, know what you'll get?
Your HVAC contractor should be able to back his proposal of a 16 SEER (or 18, 20 etc...) system and provide you with an AHRI certificate that states what the actual SEER rating is that you'll receive based on the equipment selections he's preparing to install. It's not something he'll likely have on his person but should be able to obtain once the proposal is under serious consideration by the buyer. All this said, you may still only get 15.5 but that's not bad and at least you know you're in the ballpark of what your paying for.
NOTE: It is rather pointless to ask your contractor for this type documentation when purchasing minimum efficiency equipment. This would only be to make sure when you choose higher end equipment that you get what you pay for and have the needed documentation should you qualify for any energy rebates whether they be through your supplier or federal government. None of which applies to minimum efficiency units.
Now that our new equipment is installed we can just relax and enjoy the comfort it creates while saving money all along the way...right? Well, not exactly.
Regardless of your units efficiency rating or age, if it's not properly maintained, it will not perform as it should. I repeat, it "will not"...not maybe, not sometimes, not ever. As a matter of fact, not only will you not save money, you'll likely incur more expense in repair costs. It's science.
There are 3 main things a homeowner should do or have their HVAC contractor do on a regular basis.
There are other things a homeowner simply needs to avoid to help protect the unit and make the condenser cleaning process easier and/or less frequent.
If I'm quite honest with myself, I know things can be easier to put off that I'm told to do when I don't understand why I'm being told to do them. Let me help take away the ability to procrastinate by informing you of why these things are important.
For each question, choose the best answer. The answer key is below.
The heating and cooling produced by air conditioners and heat pumps is based directly on the temperature/pressure relationship of the gas inside the system. The changing of the gas to a liquid, liquid to gas, and circulation of it is what ultimately impacts the air temperature in your home. Any changes in the required temperature/pressure relationship will adversely affect the efficiency and function of the system.
If an air conditioner or evaporators coils get clogged, it changes the amount of airflow over those coils which is used to help control the evaporation and condensation of the refrigerant, in turn causing its efficiency to drop. The air filter plays a very important role in this as well since even with clean coils, if the air cannot pass through the filter properly, it has the same effect.
Keeping this process in mind, you can likely see how the matching of the equipment we discussed above becomes important. If the coil is too small it won't catch as much air thus your high-efficiency condenser isn't all that highly efficient.
If the fan of the air handler or furnace is too powerful or weak you can see the same result as a mismatched coil and condenser. All of these components work together and matter when it comes to the actual efficiency you see out of your equipment compared to the potential ratings it is given.
You should now have a pretty good idea of how airflow impacts the efficiency of your air conditioner or heat pump and why. But beyond efficiency is the loss of comfort and gain of service calls.
Improper airflow impacts the operating temperature of motors, compressors, and ultimately the other components they use to control and operate your system. If getting the most bang for your buck isn't enough motivation to keep up on your systems maintenance, perhaps the increasing likelihood of other service calls for failed parts might get you going. Even being in the industry I didn't see the importance until I had a much better understanding of how it worked so trust me, those of us in the business can be just as guilty of neglecting our systems.
Thank you for reading and I hope I've provided you some information you can use as we head into another summer.
© 2018 Dan Reed