Heat pump blower/coil unit installed incorrectly?

Question

The blower unit in my home is installed such that the heat exchanger coil unit is on the suction side of the blower rather than the pressure side.

In this configuration I've noticed it does not seem to remove much if any moisture from the air, (based on little if any change in interior relative humidity.) Very little water if any at all (and rusty at that) comes out of the drain tube since air is being sucked into the unit through the drain tube rather than being blown out along with the water as is the customary installation I am familiar with.

The way I figure it is most of the condensate is evaporating back into the air stream and is reintroduced into the house. right now 28% RH indoors, no condensate.

I am in AZ, does this type of install have anything to do with the typical low humidity of the region or was the installer (likely the original DIY owner of the home) not thinking straight? Is it ok as is or do I need to have it "fixed" It's now 8 or 9 years old.
Thanks.

Answer 1

the blower can be on either side of the a coil and this will not affect how your unit cools or removes the humidity...the way it removes the humidity is when the warm air travels through the a-coil it causes the moisture to condense on the a-coil because it is lower in temperature than your air is...at 28% relative humidity there will be very little condensate...now all drain lines need what is called a p trap and this is shaped just like a u...if yours just has a straight drain line then you need to install one...all you need is four pvc elbows the same size as the drain line and three short pieces of straight tubing..do not glue this together so you can disassemble it in order to clean it periodically ...turn first elbow down, then a short piece of pipe, then second elbow turns back straight, then short piece of staright pipe, then third elbow turns it back up, then short piece of pipe same length as short piece on other side,then fourth elbow to straighten it back out to your drain line ..this can be next to unit or at end of drain line...what this does is keep your unit from sucking air through the drain line and not letting the water drain while the unit is running causing your a-coil to rust out faster than normal....

Answer 2

It matters not which side of the blower the evaporator is on, as long as the filter is before the evaporator.

If you are getting air into the condensate line, install a p-trap or j-trap in the line to block the air.

At 28% RH, you won't get much condensate, however. When you drink a glass of iced tea, do you get much condensation on the glass? Same is happening with the evaporator coil. There just isn't that much water in the air to collect.

To test your A/C, measure the temperature of the air in, and subtract the temperature of the air out. You should have 20* difference. If you have less than 16*, clean the indoor and outdoor coils, then remeasure. If you still have less than 16, call in a pro. If you have over 22, you have an air movement issue that will need to be addressed.

Keep Kool

Answer 3

I've installed coils in both configurations, no big deal. What seems to be missing in your case "draw through", is a trap. Make it at least 12" tall out of PVC. RScott