Central Air continuously Runs.?
Question:Hi, I have a 1.5 ton keeprite central air conditioner that runs steady. My house is 900 square feet and the furnace blower 1/3 hp. I have 2 ducts running off the furnace one six by eight inch duct with 4 six inch supply ducts running off it. The furnace also has another eight by eight inch duct with 8 six inch supply ducts running off it. The house has 2 large centrally located return air ducts that are oviously big enough. I replace my filter every month along with closing all the windows and blinds in the house along with keeping all vents in the house un blocked and open except for the basement vents. The outdoor and indoor coils along with the ducts have all been cleaned. We also had the refridgent checked in the ac and we were told that was fine. There is only a 10 degrees celsius differance between the supply and return air ducting. An example of it running steady is when it was 15 celsius outside and the thermostat which is brand new was set at 21.5 celcius and the indoor temp
Answers:
You should have about 17 to 19 degrees F difference between the return and the supply as measured at the furnace. I used the standard conversion formula for C to F and could not make heads or tails out of the temps you gave in C. Are you sure that the compressor is running steadily? Just because the outside unit fan is running does not mean that the compressor is. Are you sure it is compressing 100%? I do not know what refrigerant you are using but standard in the States is R-22 or the newest one R-22a (don't quote me on the newest). We will assume it is R-22. In order to have a 40 degree F evaporator you would have to show 69 psig on a gauge. Hope this is of some help to you.
You have some kind of problem with hot air getting into the system. If the thermostat is staying at a constant temperature and you still have hot air in the house look for unseen holes in the duct work.
i went to school for hvac. either your unit is to small for the house which is a reason why the unit would run all the time. your thermostat might not be located in the central inner wall. is it near and any doors or windows that have light shinning on it or you evaporator coil in your furnace might be undersized as well.
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