Hi All
Summer is around the corner and I would like to get better performance from my A/C. Now of course I give any specifics but..
The problem is that if I set the A/C to about 74 or higher, the humidity in the house is too high. I have to set the temp at around 70 to feel comfortable but that’s too cold for me.
I presume tht the unit is oversize for the heat load but could it be something else?
Can I just run the blower at low speed ( there is a jumber for that, I think)
House is 1200 sf main floor, 600 upper
2×6 walls with fiberglass and with 1″ pink foam outside
Chris
Replies
I'm thinking higher temp shouldn't necessarily give you higher humidity. What size (tons) is your cooling? I'm going to think a bit more today about this ... maybe add a thought later.
Sounds like the AC is too large.
If it is oversized, it cools, but doesn't run long enough to dehumidify.
Oversized AC doesn't take long to drop a degree or two, but takes longer to drop to 70... and removing humidity in the process.
Slowing the blower speed as you describe may help reduce the humidity. It most likely will decrease the efficiency of the unit, upping you electric bill too. It may also reduce the ability to get cold air up to the second floor, making it hotter. It may also allow the condenser coil to freeze up which will stop your cooling all together and potentially be damaging to the compressor.
Please note, I am not a HVAC pro so I could easily be wrong.
Wrong way to do it, though the concept sounds fine (and it will dehumidify). Slowing the blower/fan will not encourage good air flow at the register ... causing a lot of comfort problems (cold air at floor and warm air up higher).
get a $50 dehumidifier from wally world, cutting blower speed ok too.
I think slowing the blower/fan is wrong ... it will dehumidify, but there are other problems as I mentioned in another posting.
All the concerns that kurt mentions are valid, and the problems you're experiencing are definitely linked to over-sizing of the condenser.
It might be possible to install a TXV (thermostatic expansion valve) on the indoor coil. This is just a metering device installed of the liquid refrigerant line that senses the temperature of the evaporative coil and begins to throttle down the flow of liquid refrigerant when it senses that the temperature is getting low enough to create danger of freezing the coil. The effect is similar to down-sizing the condenser, but you need a qualified technician to do this, because there's a possibility of creating too much heat in the outdoor unit, since the refrigerant flow will be reduced. He will be able to assess how much the flow can be reduced without causing problems.
Thanks everyone for the replys
The unit is a Heil 5500 but the model number on the outside unit is ca5536vkd2 which I understand is made by someone other than Heil
it should be a 3 ton unit
Another issue is that we are empty nesters and there are only 2 of us most of the time altho we do get a house full on occasion
chris
What is your house size (i.e. floor area)?
What junkhound said - $50. dehumidifier; set it up with a drain so you do not have to empty it.
In addition, you might consider setting the circulating fan to run continously to better circulate the air past the dehumidifier.
Power consumption from dehumidifier and circulating fan use will be easily offset by higher temperature of the house. Not to mention you will be comfortable.........
Add a couple of ceiling fans and you may be able to bump the temperature up even further - we keep our house at 77 in the summer with a few ceiling fans and are comfortable.
Symptoms point toward oversized A/C, but I'm not an HVAC guy.
Jim
Has this been a continuing problem, or just noticed last cooling season?
3T unit may be oversized,(doubt it) 2story/ 1800sf but can't really tell without a heat load calc. You would probably be 1/2T undersized in my area and I can't see you being more then a 1/2 T oversized for your arrea.
Leaking return air duct, low charge, dirty evaporate or even a hi charge may lead to poor humidity removal.
If your evaporator is too cold or too hot it will not remove humidity efficiently.
Lowering your fan speed may lead to icing of the evaporator--just like a dirty filter.
I would have your unit serviced to rule out the easy and most efficient fix.
Make sure the tech checks superheat to insure a correct charge and consequently the correct evaporator temp.
If you still have a problem then a dehumidifier would be the quickest and cheapest fix as others have suggested.
Ok
Sounds like I need to get it checked and cleaned as a first step. What is superheat?
Chris
Superheat is the # of degrees a refrigerant is above its boiling pressure.
It is used to determine how full your evaporator is.
It is the proper way to determine a correct charge to your system.
UNLESS you have a TXV-- expansion valve- to meter the refrigerant into your evaporator.
TXV's maintain the system at a constant superheat, so you have to measure subcooling to determine a full condenser.
Edited 4/27/2009 10:51 am ET by Boats234