Using Forced Hot Air Ducts for Heat Transfer

[soupy1957]

One thing we did last year, when burning wood in our wood stove, was to turn on the blower on the furnace, (forced hot air system) and let the heat circulate thru the house.

All the rooms of the house have ductwork and get the heat, but the below-grade laundry room and family room stay much cooler than the rest of the house, because "heat rises" (of course).

Since the living room gets the hottest (where the stove is located), it also helped to even out the heat in the rooms that receive the heat naturally (or "without blower assistance), so that in the end, the living room didn't overheat, and the other rooms got a more balanced warming to them.

My issue is the "below-grade" rooms. We have space heaters down there, and they help.

I don't really have a question here........just an observation really...........that I wish my forced hot air system did a better job of keeping the movement of air warm.........it cools off very quickly.

Some of the ductwork is insulated, where other portions are not, which may have a contributing effect on the cooling down of the heat as it transfers around the house.

-Soupy1957

 

[laynes69]

You lose alot of heat when you force the air through the ducts. We heat with a wood furnace and I can have 150+ degree air at the plenum and 90 at the registers. I need to insulate the ductwork in the basement to stop some of the heat loss. Another problem with using forced air is if there are leaks in the ducting, they can bring in air from outside or other areas where you don't want the air to enter, losing efficiency. Sometimes I wish I had that bone warming heat of a stove in the living room. But when I walk from room to room and everything is even, I'm happy with the wood furnace.

 

[Backwoods Savage]

Most folks I've spoken with have had not too great of luck doing this. They have much better movement of the air by using a small fan and blowing the cooler air towards the warmer air. I know when I started doing this I was amazed how the temperature balanced out much better. It seems backwards, but it works.

 

[vvvv]

analogy= i disconnect my dryer vent in the winter & blow the heat down into the cellar, guess where the hot air goes?

 

[begreen]

the internet?

 

[begreen]

Unless all of the ducting system is very well insulated and the air handler on the furnace can be set quite low, the net distribution effect is often poor. Duct heat losses and the cost of running the motor constantly offset gains. Better to turn on the space heater down there when needed. If this is a popular location with the family, put the most cost effective heating source in that location.

 

[Wood Heat Stoves]

analogy= i disconnect my dryer vent in the winter & blow the heat down into the cellar, guess where the hot air goes?

wheres all the water go?

 

[vvvv]

analogy= i disconnect my dryer vent in the winter & blow the heat down into the cellar, guess where the hot air goes?

wheres all the water go?

water humidifies the cellar & then moves outwards to the cold [heat> cold] , as the vapor migrates thru the cracks in the fooundation walls & sill it freezes & stops the drafts

 

[Todd]

I've tried circulating wood stove heat with the furnace fan in 3 different houses and it never worked. All 3 houses had the stove in the basement and I shut the return vents upstairs so the furnace would suck the warmer basement air but it just didn't work. If you want even wood heat throughout the whole house you need a wood furnace or sometimes you can get good results with a fan blowing towards the stove like Backwoods described.

 

[weatherguy]

Put a another smaller wood stove in the basement, that should heat the whole house nicely.

 

[Cluttermagnet]

analogy= i disconnect my dryer vent in the winter & blow the heat down into the cellar, guess where the hot air goes?

the internet?

:lol: Priceless! :lol:



This comes up often. I suggest you read this thread: Fan placement?
If you scrolll down to post #5, you will find a list of other threads. You can waste about an hour reading them all- but you will learn a few things. Bottom, line- very few will offer you any encouragement on running your wood stove heat through your duct work. It's mainly a losing proposition.

But cutting to the chase, if you read the very last link in that list, titled "Makeup air from downstairs bedroom", you may find some encouragement. Good luck with it, it's a bit complicated to get it all figured out and optimized.

 

[soupy1957]

As part of our "remodeling" of our home that went on from January thru March (past) the wife had decided (no matter how unorthodox) to have the door to the basement be a screen door (like at a cottage, if you can visualize it) with screening. This was not in place prior of course. There was a regular thin wall door that we typically kept closed.

No matter how "unorthodox" this may be, ........I'm thinking that this will allow more of the cold down below grade, to rise up, and meet with the air that is warm upstairs. Since my home is fairly "tight" the hot air will not escape as easily and will be pushed around more.

I would LIKE to put another wood stove in the basement, but the space heaters should do fine. I'm not pre-disposed to really liking space heaters much however, since they have been the cause of house fires in the news, quite frequently. I dunno if that's because they don't use them properly, or what.

-Soupy1957

 

[Dakotas Dad]

No matter how "unorthodox" this may be, ........I'm thinking that this will allow more of the cold down below grade, to rise up, and meet with the air that is warm upstairs.
-Soupy1957

yes, that will be quite unorthodox, flying in the face of known physics and all.

 

[madrone]

I've tried the furnace fan and I've found the ceiling fan set on reverse is far more effective. In my case, the fan is in the same room as the stove, the downstairs living room. The stove is directly opposite the staircase to the second floor, and the ceiling fan is between the two. When the fan is off, a great deal of the heat flows across the room and upstairs, leaving the furthest reaches of the main floor fairly cold. When the fan's on, the heat circulates downstairs better. I tend to run the fan during the day, and then turn it off an hour or so before bed to warm up the upstairs. The furnace fan does a better job of cooling the house down in the summer.

 

[firefighterjake]

the internet?

 

[pyper]

If I have the room with the stove really hot (i.e., 85F), and if the back of the house is really cold, like 58F, and if I turn on the furnace blower it will cool down the hot room and warm up the cool room. Maybe 80F and 65F. So it kind of makes a difference, but not a big one.

For my rooms, I get the best effect by putting a fan near the ceiling of the hot room and blowing heat out of the room, down the hall to the west. By putting a fan in the west hall and blowing cold air into the room, the heat goes down the hallway to the east. If I put the fan in the hall to the east and blow hot air into the room, then I get even more air going into the east.

Anyway, there aren't that many possibilities -- just try out different things and see which works best.

 

[soupy1957]

I was thinking that putting a 2'x2' electric fan at the foot of the stairs leading DOWNSTAIRS so that I could blow some of the heat from the nearby room where the wood stove is, down there, but I dunno............will play around a bit til we find a good solution.

Like you, Pyper, I too can see 80º/65ºF between the upstairs and downstairs, using the furnace blower, but of course "65ºF" is kinda cool for the wife, in January, so...............space heaters!!

-Soupy1957

 

[pyper]

I was thinking that putting a 2'x2' electric fan at the foot of the stairs leading DOWNSTAIRS so that I could blow some of the heat from the nearby room where the wood stove is, down there, but I dunno............will play around a bit til we find a good solution.

Like you, Pyper, I too can see 80º/65ºF between the upstairs and downstairs, using the furnace blower, but of course "65ºF" is kinda cool for the wife, in January, so...............space heaters!!

-Soupy1957

My house is kind of like a big circle that doesn't connect -- imagine a "C" where the two ends come together and touch, but with a wall between them. I actually have a hole in the wall between them where the opening for the return is. I'm thinking about putting a hole in the back of the return and putting a blower in it, which would blow air directly from the warmest room of the house into the coolest. The positive pressure in the coolest room (with the blower going) ought to make air travel around in a circle, pushing cold air into the warm room.

I kind of don't want to mess with the duct, but it's just sheet metal, so any changes would be easy to reverse.

The only thing I'm really hesitant about is that we would need some system to avoid running the furnace blower with the hole opened (because it would be sucking unfiltered air).