Using central heating fan for circulation?

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orionrogue

orionrogue

New Member
Dec 20, 2010
53
Plymouth County, MA
Good afternoon, keepers of the flame:

Can an existing forced hot air circulation fan be used to help even out/regulate the heat coming from a wood stove insert to the rest of a house? A little background here might help...

Our home is a post-WWII Cape Cod house, approximately 1500sq ft, with forced hot air heat and central air conditioning run through the same duct work. We have both the forced air and return ductwork going to both floors. The basement has no return opening in it, but a couple heat/AC vents. Also, unlike many post-Cape homes, ours has a more open floor plan where the stairs are open to the living room, and the back BR (now an office) is half-open to the living room with only a 3/4 wall separating the two rooms. The central 1st floor hallway is very short, only 6' before you get to the kitchen.

My original intent was to buy a wood stove insert for our existing open fireplace. As with most post-WWII Cape homes, our fireplace & chimney are on the side of the house, in the middle of the living room's side wall. My wife is concerned that 1) an insert is going to heat us completely out of the room, and 2) we will freeze everywhere else. She has also been resistant to the upfront cost, which is understandable. Other than the initial chimney sweeping/inspection, I can pull the permit and handle the installation of both stove and liner myself.

I suppose my question to the group is, are her concerns about uneven heating with merit? If they are, can I use the home's existing return lines to help circulate air throughout the home and even the heat out? Will this adversely affect a stove/insert's ability to draft? Are there other concerns I should be aware of?

Any advice or past experiences would help. TIA.
 
1. Sounds like your chimney is on a outside wall - for best results it would be recommended to install a 6" stainless street insulated liner.

2. Inserts require a fan to blow the heat 'out'. Free standing stoves do not necessarily require an onboard fan.

3. Sounds like your home is a bit of an 'open style': You have to learn how to 'move air' around your home for a more balanced heat effect. The central heat vents will typically not be sufficient. Suggestion is to place a small fan at the bottom of your upstair steps, blowing towards the woodstove (blow cold towards, not heat away).
 
1) The chimney is in an outside wall. I didn't mention the liner because I figured it was outside the scope of my question, though since I mentioned being concerned about draft, I suppose not. It will be fully relined with a raincap and cover that will fully enclose the existing ceramic flue opening. At the fireplace end, the damper hole will be sealed with a steel block-off plate(s).

2) Most of the inserts I've concerned either have blowers standard, or as an option that I would want to buy. A freestanding stove is not an option due to hearth size and a low fireplace opening height.

3) The home is more open style than most Cape Code homes. Even with the heating going 70% to the first floor, the 2nd floor is usually 5 degrees warmer than the second, day or night. This makes me think that air will naturally want to circulate upstairs. Right now we keep our bedroom doors open, though as our son gets older, we won't be able to continue that.
 
I do it all the time. I have a DC motor on my Carrier Infinity96 so theoretically, it's "cheaper" to run than an AC motor. I run it on low and it does the trick. But, the disclaimer for me is that the room where the stove sits is always warmer no matter how you slice it. In my expanded raised ranch, the stove is on the lower level and in the farthest corner of the house from three of four bedrooms. Just outside of said bedrooms is my thermostat. My home is a seventies raised ranch with an addition where the latter is a more open plan but the original is typical - 3 bedrooms, one bath, 2x4 construction.

I had the addition (where the stove is) built with two return ducts right at the hearth. This is in the family room which is under the kitchen (with over 410 square feet of ceramic tile - my heat sink) and a four foot wide opened staircase from the family room to the kitchen. For the past two weeks it has been in the sub-zero to mid teens and when I am running my stove, I can keep the farthest bedrooms with 2x4 construction and R40+ in the attic at 68 - 70 when the family room (partial exposure) is 76 - 78 and the kitchen sits like a rock at 72+ (many many windows).

So, in my experience, it does work. Forced air high efficiency furnaces are all closed loop (uses direct power venting in the firebox) so running the house fan shouldn't affect your draft if the stove is properly sized and installed. I have been running this set up for 11 years.

AGE
 
oldAGE said:
I do it all the time. I have a DC motor on my Carrier Infinity96 so theoretically, it's "cheaper" to run than an AC motor. I run it on low and it does the trick. But, the disclaimer for me is that the room where the stove sits is always warmer no matter how you slice it. In my expanded raised ranch, the stove is on the lower level and in the farthest corner of the house from three of four bedrooms. Just outside of said bedrooms is my thermostat. My home is a seventies raised ranch with an addition where the latter is a more open plan but the original is typical - 3 bedrooms, one bath, 2x4 construction.

I had the addition (where the stove is) built with two return ducts right at the hearth. This is in the family room which is under the kitchen (with over 410 square feet of ceramic tile - my heat sink) and a four foot wide opened staircase from the family room to the kitchen. For the past two weeks it has been in the sub-zero to mid teens and when I am running my stove, I can keep the farthest bedrooms with 2x4 construction and R40+ in the attic at 68 - 70 when the family room (partial exposure) is 76 - 78 and the kitchen sits like a rock at 72+ (many many windows).

So, in my experience, it does work. Forced air high efficiency furnaces are all closed loop (uses direct power venting in the firebox) so running the house fan shouldn't affect your draft if the stove is properly sized and installed. I have been running this set up for 11 years.

AGE
Click to expand...

+1

Welcome, OrionRogue!!

I know several people who circulate heat with their air-handler fan, and it works great. I got my HVAC system with one of those new-fangled efficient DC fans for that reason. I think it's a great way to go. If for some reason that's not enough, you can always augment by blowing cold air around, but I'm guessing worst case your bedrooms will be a little bit cooler, and most folks like it that way anyway. I do.

HTH, and good luck!
 
Add me to the list of people who do this all the time. It works reasonably well, but like others have said, the room with the fire will be warmer. Trust me, you'll like that! You'll find that you and your family and friends will gravitate to that room.

-Speak
 
Thank you all for the responses, and pgmr for the link. My setup is a little different where instead of a sprawling ranch with a central stove location, I'm in a Cape Code house with with stove location all the way to one end of the house. But knowing that others do this without affecting draft puts a lot of confidence that, if I need to, I can do this to help distribute heat throughout the home.

You will see more of me throughout the spring, as I continue to hunt for a suitable insert for the house.
 
I don't have any numerical data to prove this works but I use my HVAC fan for balancing the temperature in the house and it works well. As has been posted, the room with the fireplace will always be a little warmer than the rest of the house but we find that ideal. My main return for the HVAC system is in the ceiling of the family room where most of the heat from the insert ends up.
 
In our home, I close all registers except the ones in the bedrooms where the heat has trouble getting to.

My son's room register started blowing out at 68* one evening. Within an hour or so, it was blowing out 74*. Not sure what the actual temp. of the air entering the return was, but I'm guessing about a 3* loss.
I turn the HVAC on in the evening when things are heating up. If I remember, I'll turn off at bedtime because those registers will be blowing cool again by morning.
House temp. might be 71* at 6a.m., but those registers are blowing 68*
 
Troutchaser said:
In our home, I close all registers except the ones in the bedrooms where the heat has trouble getting to.

My son's room register started blowing out at 68* one evening. Within an hour or so, it was blowing out 74*. Not sure what the actual temp. of the air entering the return was, but I'm guessing about a 3* loss.
I turn the HVAC on in the evening when things are heating up. If I remember, I'll turn off at bedtime because those registers will be blowing cool again by morning.
House temp. might be 71* at 6a.m., but those registers are blowing 68*
Click to expand...

Thanks for the report, TC.

Out of curiosity, are your ducts insulated, and where do the run--interior, or in outside walls/attic/crawlspace?
 
I think the general concensus is that.. it depends.

Some people report success some don't (us). Try it and see. I know that isn't a selling point with the wife, but it's the best that can be done. My ducts run in the unheated basement and attic, and the return is at floor level halfway across the house from the stove.. with a very open two story floor plan, we find our heat moves around pretty well on it's own, a fan in the dining room at floor level pointed back to the living room takes care of any uncomfortable build up of temps near the stove.
 
RenovationGeorge said:
Troutchaser said:
In our home, I close all registers except the ones in the bedrooms where the heat has trouble getting to.

My son's room register started blowing out at 68* one evening. Within an hour or so, it was blowing out 74*. Not sure what the actual temp. of the air entering the return was, but I'm guessing about a 3* loss.
I turn the HVAC on in the evening when things are heating up. If I remember, I'll turn off at bedtime because those registers will be blowing cool again by morning.
House temp. might be 71* at 6a.m., but those registers are blowing 68*
Click to expand...

Thanks for the report, TC.

Out of curiosity, are your ducts insulated, and where do the run--interior, or in outside walls/attic/crawlspace?
Click to expand...

The ducting runs through the basement and then up exterior walls. The ductwork in the walls may be partially insulated, but the basement runs aren't (yet). I'll fix that at some point.
 
OrionRogue said:
RenovationGeorge said:
Troutchaser said:
In our home, I close all registers except the ones in the bedrooms where the heat has trouble getting to.

My son's room register started blowing out at 68* one evening. Within an hour or so, it was blowing out 74*. Not sure what the actual temp. of the air entering the return was, but I'm guessing about a 3* loss.
I turn the HVAC on in the evening when things are heating up. If I remember, I'll turn off at bedtime because those registers will be blowing cool again by morning.
House temp. might be 71* at 6a.m., but those registers are blowing 68*
Click to expand...

Thanks for the report, TC.

Out of curiosity, are your ducts insulated, and where do the run--interior, or in outside walls/attic/crawlspace?
Click to expand...

The ducting runs through the basement and then up exterior walls. The ductwork in the walls may be partially insulated, but the basement runs aren't (yet). I'll fix that at some point.
Click to expand...

Much thanks for the info, OR. You estimated a 3 degree loss for the ductwork, so I was wondering if that was insulated or not. Considering your ducts are uninsulated and running through outside walls, 3 degrees seems not too bad!

Thanks again for the datapoint--it helps me in designing my own setup. Happy burning!
 
"Suggestion is to place a small fan at the bottom of your upstair steps, blowing towards the woodstove (blow cold towards, not heat away)."

Thanks for that I had been doing it the opposite way.
 
I do it frequently and for me it works great except I have to run the stove hotter since the cool air in the bedrooms gets pushed towards the front. The return air is in the ceiling in the living room 20' from the insert. On those days when the sun starts heating the front part of the house to 80º I can turn the blower on and the whole house will be an even 74-76. I do the same thing on super cold days/nights and it keeps the bedrooms much warmer.
 
My ducts are insulated and run above the basement ceiling. That's a major factor.
I really try to concentrate all air flow to just a few registers and make the most of it.

I have 3 returns. The biggest is sucking out of the loft where it's really warm. Been thinking of blocking off the one in our bedroom where it's pretty cool. A small fan placed in the doorway warms that room in a flash.
 
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