Installation Q&A Archive

Al wants to move heat from room to room

I am thinking of putting large (1'x3') vents at the top of the walls in my house. How can I determine if I should install a fan in them or rely on passive air movement? What kind of vents can I get that have a  feature to close the vent for zone heating? Any other ideas to spread heat to other rooms including upstairs?
Sincerely, Al

Hi Al,

The passive transfer of heat from one part of a house to another is a tricky proposition, depending to a large extent on the characteristics of the house itself. I think the critical factor is the energy efficiency of the building envelope. That is, the individual rooms in a leaky, poorly insulated house need a lot of heat input every hour to maintain a comfortable temperature, much more than can be supplied by passive convection from another room. On the other hand, a relatively tight, well-insulated house tends to remain at a fairly even temperature throughout, even if it is being space heated from one location. So, if your house is drafty and uses a lot of heating fuel each winter, passive convection is a hopeless strategy. That is why houses built 100 years ago had wood or coal heaters in each of the key rooms.

Also, it is my experience that convection currents take a long time to get established, so if you don't plan to run your stove 24 hours a day, passive convection will never really become an effective way to move heat.

I heat my house very effectively by passive convection, but then it was designed from the start to operate that way - it is fairly energy efficient, is oriented vertically (3 floors) rather than horizontally as in a ranch style, and the stove runs constantly.

If your house is reasonably energy efficient, you shouldn't have much trouble getting heat to go upstairs. It is getting it to flow to adjacent rooms that is difficult. Another common alternative to passive convection is to run the furnace circulation fan (if you have one) on low speed continuously. This does have drawbacks, though. It consumes a lot of electricity each winter. If your heating ducts run in a crawl space or attic space, or if your furnace is in a cold basement, you could end up wasting more heat than you move around.

Your local heating contractor probably has supplier catalogues with adjustable grilles and grille/fan combinations you can check out.

While it may seem beside the point, I think one of the best ways to improve the performance of whole house heating with a single wood stove is to invest in energy conservation projects around the house to make it more efficient. Finally, the only way you'll find out how your particular house performs with passive grilles is to try it.

JG

Wood stove clearances to combustibles

I've read much on wood stove clearances to combustible walls. But the wall where I want to install my stove is noncombustible (brick and block). Do I follow the guidelines for a "protected wall" or can clearances be further reduced since the wall itself is noncombustible?

Also, if I leave the hearth area surrounded in brick and block can I use wood furring and sheetrock 48 inches from the stove on the same wall? In other words, how much does the brick/block transfer heat to wood attached above, below and adjoining ? Thank you!

Bob

Great questions, Bob. You don't have to protect noncombustible walls, so you could put the stove right up against the wall. Mind you, the heat loss is very high through such walls, so you're going to loose some efficiency. If you put up some shielding as if the wall were combustible, you'll get quite a bit more heat into the room.

I think if you use the dimensions from the list of shield size requirements here to determine how far combustibles must be placed from the stove, you'll be okay.

John

Outside Air Source question

Hello, I enjoyed your site and read over all the information I could find on Outdoor combustion air, as well as your Q&A section. I did not see this particular question answered, so I will ask it.

I use a forced-air wood burning furnace in a basement, plus an airtight woodstove in the kitchen upstairs. Because I often had trouble starting a fire in the furnace when the woodstove was working, I surmised that the basement air was at too low a pressure to provide enough draft for the furnace (since the woodstove upstairs was drawing combustion air out of the house). I installed a metal 4 inch duct bringing outside fresh air to the combustion air inlet on the furnace, and this helped a lot. Now, people are telling me that the outside air is not a good idea, because it is so cold. If it's -20C outside, I'm pouring -20C air into my combustion chamber, robbing the fire of its heat. I hadn't thought of the combustion air temperature being a factor, but I suppose using indoor air could result in a hotter fire.

If this is true, can I put a fan with a safety thermostat on an indoor air intake, so that I get improved draft when the fire is struggling? (when first being lit) The thermostat would cut out the fan once the fire is established.

What do you think?

John 

Hi John,

Without inspecting it and running a pressure test on your house it's impossible to tell why you got an apparent improvement in start-up performance after you installed outdoor air. However, as we point out on the site, basic physics and research conducted to date do not support outdoor air as a solution. Sometimes wind plays a role in flow direction in a duct running to outdoors and if you're lucky, the wind might cause flow in the desired direction. Not knowing why you had start-up problems in the first place, makes it pretty hard to assess why the outdoor air supply seemed to help.

I would very much doubt that the wood stove operation is the direct cause of the furnace start-up problem, unless your house is extraordinarily tight.

Cold combustion air is just one more of the problems with outdoor air supplies.

If your chimney runs up the outside of the house, that is likely your problem. See the article on outside chimneys.

Have you tried just opening a window in the basement to help get the furnace started? That's what most people do to correct a backdrafting chimney. It's not a cure but a band-aid.

I think you should get a good chimney sweep in to look at the system and help you diagnose the problem.

John

Smoke spillage from system design

Hello, my name is Celeste.  My husband and I just put in our first woodburning stove.  To start, our stove is old, maybe an antique, there is no name on it, just #24 Air Tight.  We bought it used.  Our home is a Bi-level.  The stove is on our lower level, with the flue pipe 6 inch oval to round going up and out to the outer wall.  The outer pipe is triple insulated up the outside of our home.  As I read through your sight, we don't have the most ideal set up...90 degree angles, etc...  At this point we are having a few problems.   Since we did not purchase the stove brand new, no one seems to want to help...professionally.  

Our main problem is spillage of smoke into the house. This seems to happen on the onset of building a fire, but occasionally after 4-5 hours of burning, we will reload and a little smoke will come out the side door.  The stove is burning around 350 degrees.  We have a damper in the front of the stove, and in the flue pipe.  We have been playing around trying to find the right angle or opening to keep the most heat in the house.

Are we doing something wrong?  My main concern is the spillage of smoke and smell of smoke in the house.

Also, should we have a carbon monoxide detector down by the stove?   We have been getting many opinions on what to do:  Put an extension of 2 feet of insulated pipe on the outside, take off the cap, use a blow dryer to create a "warm draft", get a new stove....  Any other suggestions? I appreciate your help.  We are so excited about using the stove, we just want it to be safe and efficient.

Thank you again, Celeste

Hi Celeste,

I strongly suggest you get some professional help. Your system design is such that smoking will probably be chronic, despite whatever you do. It is not because of the elbows, but because:

1. the chimney runs up the outside wall

2. the stove is located on the lowest level of the house

3. the chimney is air cooled

Read the chimney section of the site for details.

Yes, you should definitely install a CO detector because you could have a hot backdraft late in the burn while you sleep and the exhaust from a coal bed has little smell but high CO levels.

Perfect wood heating systems have these characteristics and yours has almost none of them.

John  

Why should I believe you guys about outside chimneys?

Very nice site. Thank you.   I am considering putting a wood stove in my basement and running the chimney out the wall and up the house. I have done a lot of research on this - 'cause that's the kind of guy I am. I know that a chimney is most efficient when it is run through the warm part of the house. Yet, many people do run the chimney on the outside of the house with out any problem.

Manufacturers installation books even provide diagrams and instructions on how to do this. But you make it sound as if it should NEVER be done. Is it really THAT bad?

Also, you seem to be very against putting a stove in the basement especially with fans blowing the air upstairs. I understand the THEORIES you espouse to... but in practicality I know a lot of folks that heat their basements AND their upstairs pretty nicely with a basement stove.

As I said, I have done a lot of research. There are many other websites, books, etc on the subject besides yours. Yet your site seems to be the only information source that is SO opposed to these two practices.

Thoughts? Dave 

Hi Dave

Good questions, and probably ones that have occurred to many of our visitors.  I'll start by saying that our strong stance on outside chimneys and basement installations has nothing to do with opinion or belief.  Blame it on the laws of physics.

You might find this difficult to believe, but a good understanding of how chimneys function in relation to the houses they are installed in (or outside of) is a very recent development, certainly within the last twenty years.  The other experts you may have encountered who are not as decisive as we are on the subject have just not yet caught up with the science of the matter.  We were fortunate to have been present as the new knowledge of chimney function began to emerge.  Plus we have a combined 70 years of experience behind us during which we've been able to confirm scientific theory through field observation.  That is, we've seen a lot of spilling and backdrafting systems.

We have also seen systems that work perfectly, regardless of outdoor temperature or wind direction or speed.  Once you've come to understand the underlying physics and you've seen hundreds of systems, the patterns start to become obvious.

Just to be clear, it is the outside chimney that is the biggest problem, especially if combined with an installation at the lowest point of the house.  If you install your stove in the basement, but run the chimney straight up through the house, it will work fine, provided other good design rules are adhered to.

You wonder why so many people apparently do fine with outside chimneys and basement installations?  Here are some possible explanations from our experience:

1. They're not doing fine, they're bluffing, because most people like their wood heat system even if it doesn't work perfectly.

2. From our experience, people are incredibly tolerant of badly performing wood burning systems.

3. The problems of outside chimneys are much worse at cold outside temperatures, so folks in Georgia don't experience them as severely as people in Alberta.

4. The physics of air pressures and flows in chimneys and houses is incredibly complex and is influenced by a huge number of variables.  Sometimes those variables combine to allow a system that should not work well to perform acceptably, especially in the eyes of the owner.

We are fully aware that when you look around you will see a huge number of outside chimneys, maybe the majority, which suggests that architects and builders know something about chimney function and that we must be over-stating the problems.  They don't and we aren't, but I guess you'll have to reach your own conclusions.

Regarding the attempt to heat the upstairs of a house from a stove located in a basement, check through our question and answer section and you'll find lots of people asking how to get the heat upstairs, and that is just a small sample of that type of question we've received.  Those of us who locate our stoves properly, in the space we want to be the warmest, are much more comfortable and we burn a lot less wood.  Plus, we get to enjoy that incredible fire all winter long.  A basement is no place for something that beautiful.

John

Integration of a wood stove in to a heating system

I am new to heating with wood. Recently, we purchased a new and relatively efficient wood stove to heat our one year old, 1,350 square-foot home. Until now, we have been heating with a forced hot air LP system which has proved to be expensive. The stove is located in our basement and does a great job, but we would like to integrate it with our existing ductwork, distributing the warm air more efficiently upstairs. I would sincerely appreciate any suggestions that you may offer.

Thanks, Ben

Hi Ben,

If you want to heat the entire house with a wood burning device located in the basement, you need a furnace. It is potentially hazardous to try to use a space heater as a furnace. Plus all building and installation codes prohibit any sort of interconnection or close linkage between space heaters and forced air duct work.

We strongly recommend locating the space heater in the area you want to be the warmest, which is usually the main floor.

John

How do I  get heat upstairs?

I am building a new house with a walk out basement. I'd like to install  either a fireplace or a woodstove (preferred) with some method to  passively capture the heat and distribute upstairs... i.e. I do not want  to have to daily tend the stove . . . only fire it up when the temperature really drops.  Any suggestions? 
Jim  

Jim,
We get a lot of mail from people who have installed stoves in basements expecting the heat to rise naturally. Here is an example:
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I have a ranch home with a woodburner in the basement. I am having trouble getting the heat from my basemet to the upstairs. the door to the basement is wide open. the uptsairs is stays around 65 and the basement is about 90.   Can you offer me any suggestions on how I can even out this heat.  I put in one register but not much changed.  Hot air didn't go up, cold air came down.  My ceilings in the basement are finished with drywall.  Anything you could offer would be appreciated.
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This was my response:
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Wood stoves are space heaters and as such should be located in the space you want to heat. We strongly discourage the idea of putting a wood stove in a basement, when the space to be heated is upstairs. The problems you experience are identical to those experienced by everyone who tries this.  Whatever you do, don't try pumping air from the basement to upstairs.  This can depressurize the basement and cause backdrafting of the stove. If anything you should pump air from upstairs to the basement and force air upstairs that way.  Ideally, you should move the stove to where you want the heat because you will never satisfactorily resolve the too hot basement, too cold upstairs problem.
=============

This is what I suggest. Buy a really nice looking stove and put it it the room where you spend most of your time, like the living or family room. It will be there when it gets very cold outside to provide cozy warmth and will also provide a spectacularly beautiful fire any time the mood strikes you. You'll get the best of both worlds. 

John     

Jim replies:
John, thanks so much for the reply.  I think we will put the stove in the basement to keep the BASEMENT warm. Thanks.  

Heating upstairs with a basement stove

I was reading on your site about having a woodburner in the basement and trying to heat the upstairs. You said not to pump the air upstairs but to pump it down to the basement. I have the same problem as the other reader did, no heat upstairs and really hot downstairs.

How do I pump air into the basement from upstairs? Any ideas would be a great help because I have electric baseboard heaters and it costs me an arm and a leg to pay the electric bill!   Please help!!!!

Hi,   How exactly to force air downstairs depends somewhat on your house layout.

In simple terms you would need to install a fan that forces air from upstairs to the basement to slightly pressurize it. Then you provide a path for air to flow upstairs. Where you put the fan and grilles depends on your house. You might talk to a heating contractor or heating equipment wholesaler to get some options on fans and layout. It is not very complex.

John

Chimney through the wall      

Hi! Just found your site...Thanks for the great info!  We are installing a woodburning stove   according to town regulations.  We have cut the hole through the wall through which to put the metal chimney.  We don't have a manual to the stove we were given.  We see how the chimney connects on the outside of the house, but we don't know the best way to seal it off, meaning where the circular metal lip meets the outside of the house at the hole, to prevent rain from seeping in and what not.  Is there a typical best way to do this? 

Thanks.  Looking forward to your help.  
Roger   

Roger, 
I guess I should first mention that we strongly discourage the venting of wood stoves through chimneys routed up outside walls.  By far the more preferable approach is to run the chimney straight up through the warm part of the building.  Chimneys that run up outside walls make the system vulnerable to cold backdrafting and this is by far the most common type of venting failure with chimney vented systems.  See this page:

 http://www.woodheat.org/evilchim.htm  

The best way to seal the trim collar on the outside of a building depends a lot on what the wall covering is.  If it is lapped siding, whether wood or metal or vinyl, some installers will remove the section of siding that will be covered by the trim collar and replace it with a piece of plywood to give a flat surface to seal against.  This usually provides a slight overhang of the siding to shed water over rather than under the collar.  Regular weatherproof caulking is then used around the edges of the trim collar to seal it against the weather.  You can use silicone sealant between the chimney surface and the metal trim collar.  If you can't get the trim collar to lay flat against the wall, you may need to add a flat surface to the wall, then flash the top and sides with thin sheet metal to seal it.  It's been a long time since I installed a metal chimney, particularly one that runs up the outside, so I can't be sure I've given you the best options.  

John

My plaster ceiling is turning yellow from the stove    

This is my first year that I utilized a wood burning stove.  I consider  myself a rookie.  The wood that I used was split and I could peel the bark off.  Unfortunatly the brand new plaster ceiling started to turn color.  What  did I do wrong?  Did I used improper wood ? Marcel    

Marcel, 
If you can smell wood smoke at all in your house, then you have a serious problem and need professional support to get it corrected right away.  You should never smell wood smoke inside the house if everything is working right. 

If you can't smell wood smoke, then the discoloration probably has to do with the convection current created by heat rising off the stove.  I have a white painted ceiling above my wood stove that has been there for 11 years and it is not discolored at all.  I don't know what conditions would lead to rapid discoloration, but if you never smell smoke, then it can't be turning yellow because of smoke from the stove.

John

Is wood heat for me?    

I am considering changing my house from electric to wood heat.  Wood  heat would probably by the most cost effective option since my wood  would be free.  I need to heat a well insulated 1000 square foot house with a 1000 square feet of un-insulated basement.  The climate is northern lower Michigan, normally winter temps are about 20F but can be sub 0F at times.  What type of wood heat system do you suggest?  A lot  of people have suggested out door boilers.  Would a simple wood stove in  the basement be enough to heat the house without installing duct work?   

Thank you for your time    
Matt      

Matt,
You could heat your house very nicely with a medium sized wood stove, but we wouldn't recommend putting it in your uninsulated basement.  Space heaters work so much better when they are located in the living area that you want to be the warmest place in the house.  That way someone is around to monitor it and tend it as necessary and you have the added benefit of watching the fire all winter.  People who put space heaters in non-living area basements and hope to heat the living area upstairs with them usually find their basement is way too hot, their living area is never warm enough and they use a lot more wood than they should.  I heat from the main floor and don't put any heat in the basement and it gets chilly down there, but never close to freezing.

And your house is WAY too small to even consider heating with an outdoor boiler.  I think you would find it would smoke most of the time and deliver about half the efficiency of a good stove.

Regards,
John

Wood burning to heat several rooms

I am looking for a fireplace design that will send hot air to several rooms as well as have a nice living room view of the fire burning in a typical fireplace. I have seen something like this on THIS OLD HOUSE or one of Bob Villa's programs. Can you lead me to such a product? Thanks!      
Hopeful

Hopeful,    
There are only a few fireplaces like this: Security BIS II, RSF series of fireplaces, Regency WarmHearth, Fireplace Xtrordinare, Vermont Castings WinterWarm are about it. Check with the specialty fireplace shops in your area. They will carry one or more of these. 
John