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acproblem 02-18-2010 11:11 AM

crazy fan...
 
Here is a situation with my AC unit (fan outside the house). The average temp outside is 30 degrees. I keep temp inside the house at 74 degrees constant. I do not have any pre-programmed time schedule when temp should go up or down .. If I leave the house the temp drops top 61 and then the system turn on .. when I come back from work ..I set the time on 74 (hold on 74) and hold it for 14hrs …it takes couple of hrs to get from 61 to 74

The problem is that the fan outside the house seems to be working all the time ..it stops very rarely and sometimes there are some weird loud sounds (lasting no longer than 5 seconds) coming out of it ..
I observed that the furnace heats up the air and ..when the furnace stops working the fan keeps on going on pushes cold air from outside the house for some time..it does not get cold or anything but I think the …the temp drops and furnace goes back on …

Can you pls let me know whether there is something wrong with the system ?
I have the following brand

698B Heat Pump - Bryant

I have vents closed to my 2 other bedrooms (400sq ft each) and the space I heat up is living room, upstairs bedrooms and 2 bathrooms. The total space is (3 BR/2BA, 1850 sq feet)

Also the humidity in my house is 27% …which is a little too low . It looks like that model does not have a heating humidifier …it has cooling humidifier though ;-)
any idea how to increase it without investing thousands into new equipment ?

oldognewtrick 02-18-2010 03:55 PM

Set the temp at 70 and leave it there. The furnace will run less and you will save $$$. Your furnace runs constantly trying to catch up with the heat. You not only have to heat the air but all the items in the house that are thermal mass. Leave it set at a constant temp and see if it doesn't start cycling.

And welcome to House Repair Talk.

Wuzzat? 02-18-2010 04:27 PM

Quote:

Originally Posted by acproblem (Post 41071)
The problem is that the fan outside the house seems to be working all the time

when the furnace stops working the fan keeps on going on pushes cold air from outside the house for some time..it does not get cold or anything but I think the …the temp drops and furnace goes back on …

If the indoor furnace blower stops I'd think the outdoor compressor fan should also stop. Your elec. bill must be enormous. Avg US usage is ~700 kwh/mon, max ~3000.

Rule of thumb from another forum: for each hour you'll be away turn down the heat one [or two?] degrees, but this might only be for gas furnaces.

BTW, a 2000 sq ft house, 60 psf live + dead load, interior mostly wood, would take ~800,000 BTU to raise the temp from 61F to 74F. In a perfectly insulated house, you'd get back all this stored energy as the house cools, but houses are not perfectly insulated.

Tabletop room humidifiers of the warm mist variety kill more germs than the cool mist variety.

kok328 02-18-2010 07:58 PM

The problem your experiencing doesn't have anything to do with the tempature differential that your using. I suspect that the problem could be the contactor on the unit outside is starting to go bad. The contacts usually stick closed when they go bad. Open up the electrical compartment and inspect the contacts. If the appear to be burnt or pitted, then replace the contactor. It's only a couple of bucks ($20-40) depending on supplier.

Wuzzat? 02-19-2010 05:35 AM

The voltage drop across closed contacts that are good that are carrying rated current should be less than 30 millivolts ac. More than 100 mVac is bad.
Open contacts [no 24 vac across the contactor coil] should read about 240vac.

samw334 03-09-2010 09:41 AM

Let us know what you find. Would like the no now what the issue was?


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