high humidity with newly installed system

[that guy]

I recently had a geo comfort pardyne system installed. i have 3 ton horizontol loop field with a 2.5 ton paradyne system.

i have air handler in attic (no basement) with everything insulated.

my issue is that my weather station in my house shows R.H. from 53-65%. I complained to the installer and he had the supply rep come out to my house with him and they went over everything.

I am getting some condensate from the drain, but not sure how much itshould be. the thing cools great no problems. the unit is now short cycling. I checked the coil and there is no air bypassing around the coil, and even thought the istallers left some blown fiber glass insulation in duct there was VERY little on coil.

the supply rep tells me that the "TXV" valve is always trying to balance the freon and where you used to get 20 degree temp drop across the coil you now get more like 14 degrees and so just can't de-humidify like the old a/c systems.

he says I should not worry about the R.H., his instruments show it was around 54%.

I have not paid the installer yet because of this and want to pay if I should but don't want to if something needs to be fixed because I will not have a "carrot" then.

I've read where humidty levels above 50% can lead to mold, dust mite issues, etc. am I just being paranoid and should pay?

[dpb]

Probably...

Not sure exactly what you mean by "short cycling" -- if you mean the unit only runs for very short periods at a time in maintaining the temperature setpoint, unless the outside temperature at the present is quite cool that would indicate perhaps the unit is oversized for the house and so isn't running long enough to have time to adequately dehumidify.

How hot is it outside and what is outside humidity? If it's cool and very damp, I wouldn't worry. If it's very hot and damp, that's a little concern. If it's very hot and outside humidity isn't much higher than inside, _then_ I think the sizing calculations (there were sizing calculations weren't there?) may have been in error.

It would sound like little real reason to not pay unless there is some indication of a gross oversizing. What was the previous unit this one replaced?

BTW, I had a WaterFurnace brand geothermal unit in previous location and like it very much...I think you will be pleased.

Oh, and the above just reminded me of one thing when we did ours--it was sized on basis of heating capacity more than cooling so it had the ability to essentially eliminate the strip heaters at all. Depending on your climate, could a similar scenario have taken place here so you do have some excess capacity?

Also, do you have a variable or multiple speed compressor perchance? If so, could it be arranged to operate at lower end so could increase the cycle time and increase dehumidification some if it is a comfort issue? As for the mold, w/o a basement I wouldn't think it a major problem at that level unless you're having this high a inside RH and the outside conditions are not quite high humidity at the moment.

All this is of course subjective--I don't know where to point you to a real definitive source on the web for judging whether is "good", "acceptable", or "poor".

[Art]

How is the air flow? I bet the fan blades are full of fiberglass insulation.

[Pat]

I don't remember much about the AC from the days for following my father around as a commercial AC mechanic, but if I remember right (and I probably don't), it seems like a 3 ton AC unit is pretty big for a house. Isn't a ton 12,000 BTU so a 3 ton system would be 36,000 BTU.

If you have too large of a system, it cools the air without moving enough of it through the system. Say you have 1 system that cools your house by cycling all of your air through the system every cycle. Say another system provides the same cooling by moving only 1/4 of the air through the system in a cycle. The second system provides the same cooling but doesn't remove as much water.

I believe "short cycling" is what is described as scenario 2, above. The system comes on for a short time, does the cooling it is supposed to, and shuts off. It does it on a short on period and a long off period.

So check with someone and see if the system is sized right. 3 tons might be way too large, perfect, or way too small depending on the size of your house, insulation, etc.

Another option is to move up here, outside Buffalo. Lows in the 40s tonight and highs in the lower 70s tomorrow. What AC? ;-)) Up here you just open the windows.

Good luck.

[Pat]

BTW, as I said, I am no AC expert. Hopefully smarter people than me will have an answer for you.

[Abby Normal]

You were probably told to stay under 50% by a dehumidifier salesman.

Sustained humidities over 70% are just asking for mold. Mold does not spontaneously suck the moisture from the air and start, but what can happen is with high indoor RH, you can get some condensation happening on a surface and mold needs a physically wet food source to get started.

Under 60% is fine for comfort usually, 65% sounds high. Perhaps your system is oversized, or perhaps the 65% was measured when you had your house pulled down to a low temperature.

Are you running the fan steady on that heat pump, it will re-evaporate water from the coil when the compressor shuts off, and can result in your indoor RH being upwards to 10% higher than the what auto fan can accomplish.

A 14 dergee differential sounds like you have high air flow, and this results in less dehumidification as well.

that guy wrote:

[Abby Normal]

Or maybe you are cycling on a llow pressure switch