My basement seems to hover between 65% and 70% humidity in the basement, and 60% to 65% upstairs.
The AC cooling coil should dehumidify the air - and I've been playing with fan speed settings and things trying to acheive 35 to 40% relative humidity.... because above 40% and you invite mold and creepy critters - below 35% and it's sore throat time.
If I run the furnace fan 24/7 (so the fan is always on at 38% CFM) then the humidity goes up 5%. I think that water sits in the tray in the bottom of the furnace evaporator coil between AC cycles, and the fan evaporates it back into the house. So I'm not running the fan all the time anymore.
My air conditioner removes about 30 liters (63 US pints liquid) per day of water, as measured by a bucket. Temperature is currently set at 23C (74F)
I also run a cheap noisy portable dehumidifier in the basement for 8 hours a night that removes another 5 liters per day (10 US pints).
I have an air-to-air-heat-exchanger which is supposed to remove some humidity, but I'm not sure it does anything. Right now the humidity outside is 66%, and the humidity inside the basement is 64%.
My local HVAC contractor recommended a more efficient coil in the furnace, but I don't think that's going to help enough. They also suggested a smaller air conditioner, which would work fine this month, but it always gets much hotter outside, and inside, in August/September than it is right now, so I think the AC is sized correctly.
Temperatures by month can be found here:http://www.city.hamilton.on.ca/BUSIN...on/default.asp
Yesterday the outside temperature was 32C and the inside temperature was 22C without any strain.
They set the furnace to 1st stage 730cfm and 2nd stage 1130 cfm. At this speed it puts out a stream of water out the drain hose that's about 1/8" in diameter. I changed it a couple weeks back down to 1st stage 595cfm and 2nd stage 850 cfm. At this speed it puts out a stream of water out the drain hose that's about 1/16" in diameter. But at the lower fan speed it runs longer and seems to remove more liters/pints per day.
The AC is a Lennox HS29-24. I think the 24 is 24000 BTU, hence 2 ton. SEER 12.95. It came with a new evaporator coil and new lines (liquid and vapor) between the outside and inside. One is 1/4" and the other is 1/2". There's a filter on the line. But more interesting is a freon valve that regulates the amount of freon based on the difference in temperature between the liquid and vapor lines -- apparently this helps SEER efficiency.
The difference in temperature between the return air and the forced air is more than 20F. That is, when the return air is 65F the forced air is 40F. I stuck two meat thermomiters into the ducts permanently so it's easy to check (not accurate down in this range I'd bet, but close enough for subtraction). As an experiment I turned the AC down to 19C -- any lower and I'd be worried that the forced air would drop too close to 32F -- no problem for the AC and I had to put on a sweater which was amusing but I turned the thermostat back up to a more normal temperature.
As a potential solution to my humidity problem, I've been thinking of ordering a Santa Fe portable dehumidifier (100 pints per day, $1081US + shipping etc) (not the RX) from these guyshttp://www.thermastor.com/DesktopDefault.aspx?tabid=271
Or alternatively having my hvac contractor install a Ultra-Aire 150H dehumidifier (150 pints per day, estimated $3200 US including installation) from the same people. Word on the internet is that these are good units.
Since dehumidifiers heat the room a bit, the AC would also run a little more when it's humid. It's my hope that in the warmer dryer August/Sept that the dehumidifier would not run at all and that the AC would do the job.
What do you think? Is it enough pints? Is this the way to go, or is there a better way?
House is approximately (10m x 5.6m x 7.5m, or 420m^3; 33' x 18' x 25', or 14850 ft^3)
Here's another gaget that's compatable with my furnace as an optional extra
|CCB1 EfficiencyPlus Humidity Control (Optional)
Electronic control (35H00) installs next to room thermostat, allows selection of desired indoor humidity level during cooling mode.
During heating season control is inoperable.
CCB1 controls indoor humidity by changing indoor blower speed and compressor speed (two speed outdoor units)
Humidity level is adjusted with vertical set point slide on scale of 40% thru 60%, 50% recommended setting.
Five indicator LEDâ€™s in a bar graph configuration (MIN â€“ MAX) indicate difference in actual relative humidity and set point, indicates demand imposed on system equipment, more lights on, the longer equipment will operate to obtain desired humidity level. No lights on, humidity is at or below set point.