Here is a good approach.
Ask your AC contractor to perform a heat load calculation, and compare the required CFM for each area of the home to the available ductwork. That immediately determines a couple of things:
1) The needed capacity of the system, according to the design temperature for your locality, and
2) The ability of the system to move the cooled or heated air to the places where it is needed.
One path might be a remediation of ductwork to properly move the air, and an indoor unit that matches the outdoor unit with a sufficient blower to move the air through the corrected ducts.
[Avatar photo from a Florida training accident. Everyone walked away.]
2 Tim 3:16-17
RSES CMS, HVAC Electrical Specialist
AOP Forum Rules:
I think that the service guy needs to be replaced also a 21 degree split could be good or could be bad if the coil is dirty it will give you a high split
Did he run your numbers to know you don't have a matched system? I'd want to see that.
We are learning that it's not uncommon to lose 1/3 of your heating and cooling energy due to poorly insulated, or leaky, or too small ductwork.
The first step to solving comfort issues is a comprehensive energy audit and assessment of your home. You need to know what you have and your deficiencies before designing cures, unless you want to spend money doing the poke n hope.
Which makes more sense to you?
- turning your thermostat back and being uncomfortable. Maybe saving 5-10%
- leaving your thermostat where everyone is comfortable. Saving 30-70%
DO THE NUMBERS! Step on a HOMESCALE.
What is comfort? Well, it AIN'T just TEMPERATURE!
Energy Obese? An audit is the next step - go to BPI.org
, or RESNET
, and find an auditor near you.
If you live in the arid part of Texas, the 4 ton coil matchup to a 3 ton condensor is a good choice and in the humid part of Texas, it is still OK if the airflow is lower.
The pressure that the fan developes to drive the air through the duct system is called "static pressure". This static pressure needs to be measured between the furnace return duct at the furnace and the supply duct (if any) between the furnace and the air conditioning coil. The measured static pressure must be below .5 inches water column to deliver the full rated airflow of the furnace. Chances are that the static pressure is too hign and thus the airflow too low. Add duct leakage and you have the very problem you are living with.
I agree 1000%. I had a bearing going out on the outside unit blower motor. It would squeal for a moment when it first kicked on. I knew what it was and called the AC company that installed the unit in the first place. The guy thought I was a total idiot and suggested replacing the entire outdoor unit and he could get me a good price on it which was likely going to be a couple grand. I looked at him like he was from another planet and flat out said no thanks and that I would deal with it. I pulled the blower motor and took it to an electric motor shop who replaced it for just under a hundred.
Originally Posted by sanity
It was the second and last time I dealt with this company as each time their suggestions have been high dollar resolutions to what was really a low dollar problem.
So yes, there are dishonest people out there who take advantage of folks and especially more so when the temp is 100d or more and they think they have you over a barrel.
Originally Posted by bldfw
It would likely fall on deaf ears, but I'd be interested in reporting that company to The BBB, manufacturer, and possibly the state attorney general. You never know, if they get enough complaints similar to yours they might act against that company.
I've dealt with a one local company by spreading the word that they are not properly trained, don't know the equipment and controls, and do poor quality work and they should look elsewhere. I give them multiple examples if needed.