Whole house HVAC fan and wood burning insert
- Thread starter gnxfan
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
You can try it and it may help some, but I'm guessing not alot. You might do just as well not closing off the upstairs cold air return, since you're trying to get the cold air out of the floor anyway.
May help some, but in general, central HVAC ductwork is somewhat 'lossy' - little cracks and seams where the air can leak out. Plus, they are generally designed to handle a relatively low volume of relatively hot air. You want to move a large volume of relatively cool air. On top of that, the ducts usually pass through unheated space (attic, crawlspace, ect) and loose some of your heat.
Should be pretty easy to give it a shot, but you may find that a few well placed fans give you better heat distribution.
Should be pretty easy to give it a shot, but you may find that a few well placed fans give you better heat distribution.
Thx for the quick reply. So, do you think a ceiling fan at the top of the stairs on 'pull' would help?
We keep a fan on the floor in our foyer that blows cool air into the living room where the stove is. Warm air comes out the top of the doorway and goes dancing up the stairwell. If you go to the top of the stairs, you can feel the cold air going down the steps along the floor and the warm air coming up by the ceiling.
The temperature differentials are what create natural convection, and are your friend. The ceiling fan will only mix up the air, eliminating temperature differentals, killing the natural flow.
Dan
The temperature differentials are what create natural convection, and are your friend. The ceiling fan will only mix up the air, eliminating temperature differentals, killing the natural flow.
Dan
If your ducts are all inside the house, try it and find out. It shouldn't cost much to test this out. Tape some cardboard over some of those vents. Keep in mind that the air handler requires air to flow back to it unrestricted, so if you shut vents off, some more need to be installed or opened up somewhere else. If the experiment works, have some return air vents installed downstairs. Keep in mind certain building codes require some space between the wood stove and the cold air return vent, check them before adding venting. It would be best to involve your heating/cooling man.
It helped at our house with a wood stove. The wood stove is in the basement with a cold air return nearby on the ceiling, HVAC air handler is also in basement in another room. We closed off one cold air return that is high on the wall upstairs(leaving the ones close to the floor upstairs open), and opened the stairway door to the basement. Our heating service man had previously installed some additional cold air returns in the basement because the original system didn't have enough air going back to the furnace. Our HVAC thermostat has a "circulation" setting, that runs the air handler about 33% of the time. What had been a difference of 5-10 degrees cooler upstairs is now 5 degrees cooler to the same temperature as downstairs (depending allot on air temp and wind outside). I now have the circulation setting set to come on only early morning and evening to cut down on the amount of time the fan runs. I still have some problems with circulation within the rooms in the basement, but the upstairs is much warmer now.
Most thermostats will allow the fan to be run all the time, and I tried that with an older thermostat, but it was moving the air too much. Even though the air temperature was close to the same as downstairs, the moving air was uncomfortable to me. When the new thermostat was installed, I had them set the air handler to run the fan slower for the "circulation" setting, and you can hardly tell the air is moving, but does a good job of circulating the air.
It helped at our house with a wood stove. The wood stove is in the basement with a cold air return nearby on the ceiling, HVAC air handler is also in basement in another room. We closed off one cold air return that is high on the wall upstairs(leaving the ones close to the floor upstairs open), and opened the stairway door to the basement. Our heating service man had previously installed some additional cold air returns in the basement because the original system didn't have enough air going back to the furnace. Our HVAC thermostat has a "circulation" setting, that runs the air handler about 33% of the time. What had been a difference of 5-10 degrees cooler upstairs is now 5 degrees cooler to the same temperature as downstairs (depending allot on air temp and wind outside). I now have the circulation setting set to come on only early morning and evening to cut down on the amount of time the fan runs. I still have some problems with circulation within the rooms in the basement, but the upstairs is much warmer now.
Most thermostats will allow the fan to be run all the time, and I tried that with an older thermostat, but it was moving the air too much. Even though the air temperature was close to the same as downstairs, the moving air was uncomfortable to me. When the new thermostat was installed, I had them set the air handler to run the fan slower for the "circulation" setting, and you can hardly tell the air is moving, but does a good job of circulating the air.
I tried it with ours, and found out that our stove heated our house better with it off. A difference of almost 3 degrees in each room. I figured it was due to the air being sucked down to our cold basement before being blown to all the rooms. When we are heating with wood, our basement cools to below 50*F.
1. MOST of the folks commenting over time have reported that using the HVAC system to move stove heat around did little or no good, some found it a net loss. - It isn't what the system was designed for.
2. It is generally better to work on moving cold air towards the stove, than it is to try and move hot air away from it. Cold air is heavier and will push the hot air around much more than you can push cold air with hot air.
3. Find your natural convection patterns and work with them. Many people find it helps to hold a lit candle or an incense stick in doorways, stairwells, etc. at both floor and ceiling levels, and watch which way the smoke/flame goes. You will generally do better to enhance what's already there as opposed to fighting it, or creating a new pattern.
4. Experiment - every house is different!
Gooserider
2. It is generally better to work on moving cold air towards the stove, than it is to try and move hot air away from it. Cold air is heavier and will push the hot air around much more than you can push cold air with hot air.
3. Find your natural convection patterns and work with them. Many people find it helps to hold a lit candle or an incense stick in doorways, stairwells, etc. at both floor and ceiling levels, and watch which way the smoke/flame goes. You will generally do better to enhance what's already there as opposed to fighting it, or creating a new pattern.
4. Experiment - every house is different!
Gooserider
Generally, this is not very effective except in some houses with well insulated ductwork completely in the heated space.
Also, if properly designed and installed the system is balanced for the fan size. Blocking off vents and/or returns can cause the motor to race and burn out faster.
Also, if properly designed and installed the system is balanced for the fan size. Blocking off vents and/or returns can cause the motor to race and burn out faster.
My kill-o-watt told me that the circulation fan on the whole house system takes 500 watts. If you electricity costs 14 cents/KWH, you're spending seven cents an hour to blow (mostly) cold air around.
- Status
Similar threads
