Increasing house air flow with added traps

[Daveln88]

Hi all. I really want to get a wood stove but the logistics are unfavourable.

The wood stove would go in the basement (insulated, but in the 1960s, so not very well) but I really want to at least partially heat upstairs as well. The problem is I don’t have an open stairwell connecting the two. The stairs are basically an addition outside the house (used to be two separate homes), and with three exterior walls and big windows this stairwell is a huge heat sink and very cold in winter. We have doors at top and bottom to mitigate the problem, but this means I have no air flow bottom to top.

Basement is finished with sheet rock ceiling as well. I also have a forced air furnace which would help circulate heat some I think.

My questions are: is a wood stove viable for me? Are floor traps for added airflow essential? How many would I need for an 800 sq ft area?

Thanks so much!

 

[SteveKG]

What is a floor trap? A vent or something?

 

[Daveln88]

What is a floor trap? A vent or something?

Yes. Maybe that’s not the right term. But basically cutting holes in the floor and potentially one with a small fan in it.

 

[EbS-P]

Hi all. I really want to get a wood stove but the logistics are unfavourable.

The wood stove would go in the basement (insulated, but in the 1960s, so not very well) but I really want to at least partially heat upstairs as well. The problem is I don’t have an open stairwell connecting the two. The stairs are basically an addition outside the house (used to be two separate homes), and with three exterior walls and big windows this stairwell is a huge heat sink and very cold in winter. We have doors at top and bottom to mitigate the problem, but this means I have no air flow bottom to top.

Basement is finished with sheet rock ceiling as well. I also have a forced air furnace which would help circulate heat some I think.

My questions are: is a wood stove viable for me? Are floor traps for added airflow essential? How many would I need for an 800 sq ft area?

Thanks so much!

Have you considered a spiral star case?

 

[Woodsplitter67]

If you put them in the right place you should be able to make a convection loop. I would do 2 2x3 vents in the floor that should be near the stove and use the steps as the cold air return to move the air..youll need a bigger stove most likely the basement will absorb a lot of heat

 

[begreen]

It is possible, but with some caveats. The house could be setup like an old gravity furnace with a large grate above the stove and an equal area on the opposite wall for the returns. This could be something like a 20"x20" supply grate and two 10" x 20" ( or three 6" x 12") return grilles at the opposite side of the house, assuming that there is free air flow upstairs from one side to the other. If there are closed off rooms on the opposite side then the returns may need to be relocated to a more open space. Hard to say without seeing a floor plan sketch.

Definitely check with the city authorities to find out what stoves are permitted in Montreal. Also most jurisdictions will want fusible link fire dampers in each of these floor holes. I know where to order them in the US, but not in Canada.

 

[Daveln88]

It is possible, but with some caveats. The house could be setup like an old gravity furnace with a large grate above the stove and an equal area on the opposite wall for the returns. This could be something like a 20"x20" supply grate and two 10" x 20" ( or three 6" x 12") return grilles at the opposite side of the house, assuming that there is free air flow upstairs from one side to the other. If there are closed off rooms on the opposite side then the returns may need to be relocated to a more open space. Hard to say without seeing a floor plan sketch.

Definitely check with the city authorities to find out what stoves are permitted in Montreal. Also most jurisdictions will want fusible link fire dampers in each of these floor holes. I know where to order them in the US, but not in Canada.

Thanks so much. This is similar to what I had in mind but to be honest I wasn’t planning on such big areas for the vents. Thanks!

 

[Woodsplitter67]

Thanks so much. This is similar to what I had in mind but to be honest I wasn’t planning on such big areas for the vents. Thanks!

You really dont want to actually heat the basement, you want the heat to rise up easily to the main floor. My brother lives is a 1940s farm house that was gravity heat. The vent in the floor is a 2x3 with an extremely nice grate on top. The house I was born in was gravity heat also. The basement will absorb some heat, but a lot will heat the upper floors if you do this right. You need to make a convection loop. You may want to do a half door to the basement door so the heats trapped and goes out the vents and not through the stairs.. keep the bottom half of the door open at the stairs to have the cold air return to the basement.

 

[begreen]

keep the bottom half of the door open at the stairs to have the cold air return to the basement.

My concern with that plan is that during coldest weather it could introduce a large temperature drop in the return air which equals heat loss. Also, I am unsure of the stove location in relation to the exterior stairwell. If the stairwell is far away from the stove then that would mean pulling the cold air across the basement. If it was close by then the convection loop would be local and not circulate heat throughout the first floor. Seeing a floor plan would help.

 

[stoveliker]

I understood the stairs are cold, i.e. poorly insulated (windows). As a result a gravity system would result in "extra cooled" air coming into the basement from the (poorly insulated) stairs.

To have an efficient loop, one should either insulate that stairwell very well, or keep it closed and actually make vents for both rising and dropping air.
The way to do that is for the return (to the basement) air vents to have a chase extending down from the vents until about 3 ft above teh basement floor. Cold air will sink there, warm air will rise through the vents without chases.

I'd keep the stairs out of the picture here.

 

[moresnow]

The way to do that is for the return (to the basement) air vents to have a chase extending down from the vents until about 3 ft above teh basement floor.

Could you please post pictures of how you have done this in your installation/installations. It will clarify nicely. Thank you.

 

[kennyp2339]

I installed a floor grate with a 6" boot, inside the boot I put in a 85cfm fan, the pan draws along the ceiling of the basement and then blows hot air out the grate, works pretty well to and is quiet, all in all cost me about $50 worth of material.

 

[stoveliker]

Could you please post pictures of how you have done this in your installation/installations. It will clarify nicely. Thank you.

Spent 30 mins to find what I mean on YouTube, but no luck. I've seen it done. Sketch attached.
Hot air rises through a grate/register from a basement install to the living room. Cold air drops through the other register down into the basement. Warm air can't go up through the cold air return because of the chase blocking access to the register.

However, I have something like @kennyp2339 now. My inline duct fan was mounted a joist between basement and living room, blowing 90+ air into the living room. However, despite me being conscious of noise when mounting the fan, I think I can do better. So I have now reversed the fan, added a flexible insulated duct from the register to the side wall of the basement, and all the way down to the floor. The fan is now on the basement floor (no noise into the wood living room floor anymore) sucking cold air through the vent register and the duct and blowing that into the basement at floor level. The warm air is now being pushed up through the stairs (that are open). Will see how that goes this winter.

 

[kennyp2339]

I think you guys are looking for this - gravity vents for woodstove

 

[Bad LP]

Have you considered a spiral star case?

There is NOTHING worse than these in a house.

 

[EbS-P]

There is NOTHING worse than these in a house.

If you don’t have access to the basement it is a solution that connects spaces. We put one in and it looked nice, was functional. For the space we had there were no other solutions that didn’t put a stairway in the middle of a room or in front picture window. Agreed not for everybody. But if you have to go outside to and come in a separate entrance to tend a stove it could be solution.

 

[Shrewboy]

Thanks so much. This is similar to what I had in mind but to be honest I wasn’t planning on such big areas for the vents. Thanks!

Yea from everything I have read on this forum, the vents need to be huge or the amount of air that moves around through natural convection will be too low. I am looking into running my oil furnace fan in "circulation mode" so it basically just blows air through the system, im hoping this will help even out the temps in the entire house (and allow the basement to get some heat so my pipes dont freeze on those really cold nights)

 

[stoveliker]

Indeed, big or forced convection. I use a 6*10 vent with a fan. Still, as was originally pointed out, creating a loop/circuit for the air to move is needed.

 

[Bad LP]

If you don’t have access to the basement it is a solution that connects spaces. We put one in and it looked nice, was functional. For the space we had there were no other solutions that didn’t put a stairway in the middle of a room or in front picture window. Agreed not for everybody. But if you have to go outside to and come in a separate entrance to tend a stove it could be solution.

I've got one that is the only way to the space above the garage that's 24X24. Great space, tons of glass and views, very quiet and it gets its access thru the side wall that is partially attached to the main house. Cant move anything with any sort of ease up or down. In fact my office was up there for years and I've worked from home for a very long time. I hated that thing with a passion!!

I'm now downstairs and have been for about 10 years now and if I never go around that thing again I'll be a very happy man.

 

[kennyp2339]

Got a little stuck on one in a house fire about 8 years ago, never looked at them the same way again.