As a homeowner myself and a Professional Home Inspector in the Dallas Fort Worth are for years I just had to tell somebody about some of these ideas that companies are trying to get us to believe. I hope this helps understand some of these issues.
Homeowners there are literally hundreds of products and devices being promoted everyday in the HVAC industry that claim to reduce energy or increase the capacity of AC systems by huge percentages. Do not become another victim of dishonest contractors and ideas that offer to good to be true results. Listed below are some of the most popular items going around in the business today.
1. Refrigerant and Oil Additives- The claims being made by installing these into your AC system say you will see incredible energy savings in the 20 percent range! These additives have been around for a long time. There have been hundreds of hours and thousands of dollars spent in trying to prove these claims by research laboratories. Many of the results from these tests indicate no change in system capacity or performance. If there are 20 percentage points to be gained in energy efficiency then the top equipment manufactures will be doing all the promoting and selling not small independent contractors selling these miracle additives. Homeowners also need to be aware of the impact on the warranty of your AC systems. Most all of the major manufactures do not recommend anything in a refrigerant system other than the proper refrigerant and the factory recommended oils.
2. Refrigerant Management Devices-These add on devices are advertised with enough "Tech-No-Babble" that would even confuse a NASA scientist. The idea is that these devices re-align the refrigerant molecules into a rotating flow mass to reduce laminar flow and friction losses throughout the refrigerant piping on the liquid side of the systems. Again there have been thousands of dollars and many hours spent by testing laboratories to verify these claims and how much they could reduce your energy consumption or increase the cooling capacity of an AC system. The results are not conclusive in determining that these devices can in fact improve efficiency or capacity of a system. Any under performing AC system will seem to operate better after installing one of these devices if it is not up to design conditions in the first place. The first thing that should be done is to verify the performance of an existing system and make sure that all heat transfer surfaces are clean, the proper refrigerant charge is in the system, the refrigerant is not oil logged already and there is design air flow across both the evaporator and condenser. When these items are done and in place you will see that other add-on devices are not be needed to achieve the design capacity and performance of the system.
3. Motor Mizers, Harmonic Filters, and Electrical System Stabilizers - I like to refer to them as "Little Black Boxes with Wires". These are high on my list because they are one of the most common products I have seen out there and unfortunately for many they are even being sold! These devices will gain you as advertised by some companies 26-34 percentage points in energy reduction! I have talked with many electrical engineers about these devices and they cannot reduce the KW of your system by 26-34 percent period! Again if these types of devices really produced the savings that are claimed then the utility companies would be promoting these ideas and technology and installing them at no charge to the consumer to help reduce the demand on the utility grid.
4. High Efficiency Air Filters- I will no doubt catch a lot of grief about this one but I am used to it. I will start out to say here that having good clean air filters is a must for any AC system and for any homeowner. You have to understand a little bit about electrical energy and motors not to be tricked by this popular method contractors use to get into your back pocket. A dirty air filter in your AC furnace will consume less fan energy than a clean one! Now you can re-read this again and it says that; a dirty air filter in your AC furnace will consume less fan energy than a clean one! This is not a typo it says exactly what I wanted it to say. The next time when you need to
change a very dirty air filter in your furnace perform this simple test. Borrow a meter that can measure the amperage of the fan motor. If you do not have one or get a friend who is an electrician and take the amperage reading on the fan motor before you change the filter. Be sure and take the reading with the fan compartment door in place like normal operation. Take a few readings and record them over a five minute time period. If you are taking these readings in the summer be sure to let the unit run for a few minutes while taking the readings to get a fairly accurate and stable reading. Now change the filter(s) and take the readings again for the same amount of time and with the fan compartment door in place. You will find that the fan energy or KW increased by some amount. Depending on exactly how dirty the filters were before changing them out will determine how much change in amperage or KW you will notice. What you may notice after changing the filters out is that the home feels more comfortable and the AC system may run less to keep the home cool. This is where the energy savings show up if there going to be any at all. The increase in air flow across the evaporator coil because of the new filters will increase the fan energy or KW, but the overall amount of time the unit runs may be reduced resulting in energy savings. This needs to be understood very clearly because there are a lot of contractors out there selling very expensive and sophisticated air filtering systems guaranteed to save you a lot of money. In my opinion the best air filter for the money are the pleated type filters in the one, two, or four inch thickness that are changed frequently. Make sure that the filter compartment is air tight and that the filters fit well in the filter rack or frame and do not allow air to bypass the filter. You cannot go wrong with regular filter replacements and using good pleated filters. Now there is one other thing to know about air filters that is very confusing to homeowners and that is that air filters have an efficiency rating. The ability of a given air filter to remove particulate matter from the air stream is rated in efficiency by how much of the airborne particulate matter it catches by passing through the filter once. This efficiency is not to be confused with electrical efficiency or energy reduction.
5. Magnets- I guess as long as I am alive there will be someone or something that will come along every once in awhile who will make an incredible claim about magnets. In the HVAC industry I have seen magnetic devices promoted to treat water that is used in very large commercial and industrial systems instead of the traditional methods of using good science and chemistry techniques to treat water. In the residential sector magnets have been advertised to save you 20-25 percent in your gas energy bill by using them on your gas piping serving your gas appliances such as your heating furnace. By simply strapping these magnets on your iron gas piping they supposedly re-align and straighten the gas molecules in the stream of gas flowing to you your furnace before the gas reaches the burner section. Again this is just one of many devices and products being pushed on homeowners who have not been informed as to what is happening out there today. You may want to talk with your local gas utility provider as well on this one.
6. High Efficiency Capacitors- There are some contractors out there today who are selling unknowing homeowners new capacitors for their ac units because they are telling them the capacitors are out of the normal range or value for a capacitor. Do not fall for this gimmick. A capacitor is basically either good or bad and no in between condition. A capacitor will have a different reading in micro-farads based on if the capacitor is hot or cold. A warm capacitor that has been in operation will read differently than a cold one out of the box. Do not let a service technician fool you with this trick. If a capacitor fails either the fan(s) or compressor will not start. A bad capacitor is a valid reason for replacing a capacitor. But capacitors will not improve the efficiency of you're A/C system by any significant amount that you can measure or will see in a lower electric bill.
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