Using the central air/heating blower

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bayshorecs

New Member
Hearth Supporter
Sep 28, 2008
214
Central Illinois
Still working on ways to move the heat from the stove room to the bedrooms. I have a blower on the stove, a box fan point at the stove from one room and another fan at the bedrooms pointing air back as well.

I have also started to mess with closing returns and vents on the central forced air system to move the heat around. So far, I have all the fans and the forced air fan running and the house is close to the temp I want.

The question I have is about the amount of elec it takes to run the central air fan 100% of the time vs running the other fans. I would hate to swap my gas bill for an elec bill because the blower is running all the time.

any thoughts?!?
 
I would leave the vents and returns all open. Closing them down too much can cause the static pressure in the system to rise, which is hard on the blower.

As to the cost, it depends on the furnace. A high efficiency model with an ECM motor can use less than 100 watts on low speed. A conventional furnace with PSC motor can use 4-500 watts.
 
'Bout a bazillion threads on this subject, or at least dancing around it. Here's just one recent example:

https://www.hearth.com/talk/threads/28698/

A lot depends on the configuration of your system. You may lose more heat while the air's traveling through the ductwork than it's worth. Or, if your house is built just right, it might work for you. Rick
 
You could attach a ThermGuard to your furnace fan thermostat. It allows you to run your furnace fan periodically and save some energy there. Many people cycle for 10 minutes every hour and find that helps quite a bit.

You can find more information at www.bearmountaindesign.com

Here is a quote from gooserider from: https://www.hearth.com/talk/threads/5077/

“We have found a reasonably satisfactory solution. Our house basically divides into 3rds. On one end is the living room third with the stove, which is totally open to the peak of the cathedral ceiling 24 feet up The other two thirds are two story with nominal 8’ ceilings - The second floor is the master suite, and a small loft area open to the living room. On the first floor is the kitchen / dining area that occupies the center third of the house, then two bedrooms and the main bath in the far third.

Underneath everything is a full basement, with an open area under the living room and kitchen thirds. There is a half bath, the furnace room and a storage room under the bedroom third. It is a beautiful house, but not a very practical one.

There are large passageways between the kitchen and living rooms, and the stairs to the 2nd floor and basement are very open. The first floor bedrooms are in a sort of “T” hallway.

The stove used to do a good job heating the living-room, dining area and master suite, but didn’t do much for the bedrooms. However I’ve gotten a ”Thermguard” from Bear Mountain Design, which is intended for addressing this sort of application. It is a little box that wires in across the fan terminals of your HVAC thermostat, and cycles the fan on a programmable basis. Since we’ve gotten the box, I typically see no more than 1-2*F difference between the living rooms and the bedrooms. As long as I stay on top of keeping the stove loaded, I can keep the house in the low 70’s.

Currently I have the box on its default programming of running the fan five minutes on and 15 off. Haven’t seen any real reason to change it.

(The box also advertises itself as useful in hot water systems for periodically circulating the water to keep if from freezing)

The downside is that I seem to be loosing more heat from the living room than I’m gaining in the bedrooms - It used to be the bedrooms would be in the low - mid 60’s, and the living room would be near 80. Now everything is closer to the 69-72 range.

I’ve been thinking about trying to play games with blocking off different registers and returns to see if I can focus the distribution a bit, but I haven’t decided which way I’m better off doing it - blocking the intakes in the living room and the registers in the rest of the house, or vice versa.

Gooserider”

Cheers,
John
 
pgmr said:
I would leave the vents and returns all open. Closing them down too much can cause the static pressure in the system to rise, which is hard on the blower.

As to the cost, it depends on the furnace. A high efficiency model with an ECM motor can use less than 100 watts on low speed. A conventional furnace with PSC motor can use 4-500 watts.

... and would cost about $50 a month in electricity if run 24/7. If it keeps you from turning on the oil or gas burner, it may be worth it.

I run our furnace fan at night (9-7) to spread the heat around. This is when the temperature differences are probably going to be greatest and it lets me get some humidity in the air from the central humidifier as well as filter out some of the dust. I think it is probably worth the buck a day or so that this costs to keep the rest of the house warm.

Chris
 
Not sure what kind of blower I have. It is installed in a Trane unit from the mid 90s.

Right now with all these fans running, I fear the electric bill will overcome the normal $150 per month increase during the winter months I would normally see for gas and electric together.

I would hate to cut passive registers in the floor since the house is only 13 years old. Maybe having the furance running normally along with the stove running 24/7 would be the best cost option since the furance would obviously be running less with the stove running...

The attic insulation is around R38 I believe. It is blown in and just covering the joists. Maybe it would be more cost effective to increase that to R50 or so?
 
ThermGuard would not interfere with the normal operation of your furnace. If your set the thermostat to 60 degrees, your furnace would kick in if it dropped below that point. ThermGuard would just cycle your fan to get the temperature above that set point. In this way, your fan would not be running 24/7 and you would have the furnace to kick up the temperature in the event the pellet stove could not keep up.

Cheers,
John
 
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