Cut the energy usage of your forced air cooling (or heating) system

Cut the energy usage of your forced air cooling (or heating) system

using low cost, low technology, do it yourself methods

I am not selling anything here, this method, including details and answering your questions, IS FREE!!

Most attempts to use less energy to heat or cool your home (or business) are successful, but, you are less happy.

An example is :
Changing the thermostat (who enjoys being warm and humid in the summer or cold in the winter!!??)
We hear about the methods over and over in the news. They are simply methods of saving energy that are not successful.
Why are they not successful? Two reasons; we do not like change, and, the energy savings methods make us less happy!
If you question why I was able to find enough different methods to reduce my electricty usage see my post about saving electricity be modifying the exhaust duct of your clothes dryer.

Our Forced Air Heatpump
My next project would have to be the heatpump. Again, this was something that effected everybodys comfort, and used lots of energy. The results of this change will be similar for ANY forced air system, natural gas, propane, combination, or electric. I knew my plan would not save half of the energy used, but, there was going to be BIG side benefits.

  • The house was going to stay cleaner
  • The system would last longer
  • Fewer air filter changes would be required

I was ready to do this project!!

We hear everybody telling us, “Change your air filter frequently, you will save energy!!”
WHY!!?? Well a dirty filter does several things:

  • Reduces the air flow through the furnace
  • Makes the fan work harder
  • Lets dust, pollen, and dirt go through the filter!!

The reduced air flow causes a higher differential temperature across the furnace, the higher, the less efficent. The lower the difference is between the inlet and the outlet, the more efficent. It is that simple!!
The harder the fan works, the more electricity it requires to run.
The dirty filter acts to block airflow at the filter. After the filter is blocked enough, dirt will go right through the filter, damaging your furnace, staying in the ductwork, and worst of all, will be blown back into your home where you will have to clean it by dusting and vacuuming!!
Also the reduced air flow reduces the amount of moisture the air conditioner can remove. This makes the home more uncomfortable. Besides removing heat, a primary function of a air conditioner is to dehumidify the home. If the unit does not efficently remove moisture, you will lower the thermostat setting to maintain comfort. Rapid reduction of moisture means less on time for your A/C system. We want to be happy!!
In the north, many homes have humidifiers. During winter months, the humififier raises humidity, improving comfort. Again, the dirty air filter will inhibit the effectiveness of this system.
I needed a fix to my air filter problem! The original filter for my heatpump was a 20″ X 20″ X 1″ throw away.
It was located in the basement, and was always forgotten!! My system, similar to many southern homes, only had one air return in the hall. Years ago I had eliminated the furnace mounted filter and relocated it to the hallway where I would be reminded to change it more often.
The new location used the same filter, a 20″ X 20″ X 1″ throw away. The only difference was convienence of my ability to change the filter. One time I bought a filter that included a “whistle”,  the filter would whistle when clogged while the fan was trying to pull air through the filter.
This whistle soon taught me the filter needed to be changed monthly, or more!! One time I started to change the filter and the fan started. I decided to just go ahead and change the filter. Well I got a surprise, I could almost not remove the filter!! The suction of the air conditioner fan was so great, it was holding the filter in the frame!!
That was when I decided this had to be resolved!! I was spending money for electricity, and not receiving the comfort!!
I looked at the filter. It was a pleated media designed to capture dust. It worked better than the cheapo woven fiberglass filters which captured almost no dirt, but, the pleated media reduced air flow shortly after installation!! The way to make the filter change interval longer and make the system more efficent (use less electricity), was to have more filter media surface area!! The greater area would mean:

  • More time between filter changes
  • Less air flow loss because the filter would not be “blocking” the air flow as much
  • The air would be going through the filter slower, the filter would be more efficent at capturing very small, slow moving dust particles

My first thought was to add another filter somewhere. The more I thought about it, I realized I needed 3 more filters!! That wasn’t going to happen. My wife was lienent with my changing things in the home, but, a row of 4 air filters in the hall wasn’t going to happen!! Back to the Big Box Hardware Store (BBHS)!!
Like the exhaust vent for the clothes dryer, this solution was not obvious. I actually went to 4 BBHS’s before I ran up on a solution. New homes were being built with a new type of filter, a 20″ X 25″ x 4″ filter!!

 Click on the images to enlarge!!

Not only was the filter 25% bigger, it was 4 times as thick!!

This new filter would be 5 times the filter area of my old 20″ X 20″ X 1″ filter!! Just what I wanted!! The air would go through the media at 1/5 the speed resulting in much lower pressure and capturing much more dust!
I had to have it!! BUT, the only way it was offered was as part of a $7000 new heat pump system. That wasn’t going to happen, it didn’t fit the previously described 80-20 rule, not by a large margin!! The replacement filter was offered, and it happened to be the same width and height as the 20″ X 25″ X 1″ filter. The only difference was the 4″ depth.
I knew I could make it work! In the duct work area of the BBHS, I picked up a new register grille that was designed to hold a 20″ X 25″ X 1″ filter. I had some aluminum flashing at home.
I enlarged the hole in the wall to accomodiate the new 5″ wider filter grill. Now the hard part, I cut the rear lip off the new filter grill and extended the depth to 4″ with aluminum flashing.

The assembly was pop riveted together. The competed new grill was mounted in the enlarged opening and nailed/screwed into place. The new 20″ X 25″ x 4″ filter was installed.

I was amazed! The filter exibited none of the pressure when trying to remove it like the 1″ filter had. Even after 4 months the filter was not in need of replacement. Yes there was a coating of dust, but, no blockage like its predecessor!
Within a week everybody noticed the home was staying cleaner. Only 10% of the dust seemed to build up between dustings. This was a big plus.
The users were happy, and, I had achieved the savings I was trying for.
So the savings were:

  • The heatpump was going to last MUCH longer
  • Summertime humidity was lower, the air conditioner had to run less to keep us comfortable.
  • Home cleaning was easier
  • Filter change interval was extended dramatically
  • Oh, yea, we use less electricity

What more could you ask for!!??
P.S. My daughter since bought a house. Yep, within a month I had updated her return air filter with a 16″ X 25″ X 4″ filter.
Keep looking for my next step into reducing my total electric bill by half.

If you like this idea, download the CADplans Corp. catalog at the right, for some really great ideas.

Still have a question after reading this? Leave your question in the comment box, I will answer the question, if possible.

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