Open fire in a tight house ?
GBA Editor
| Posted in General Questions on
My better half has absorbed the logic of “build tight, ventilate right” but still has a hankering for an open wood fire in the living room. Is there any hope of this or are we just going to need lots of garden bonfires to smell woodsmoke ? BTW it’s not just the smell but the sound…
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Dear Interested,
It's very hard to integrate a traditional wood-burning masonry fireplace into a new home with low air leakage rates. I would suggest you consider installing a wood stove with glass doors; some models are designed to allow the doors to be opened for enjoying the fire.
Why don't you put a fireplace outside on a patio or porch? The colder the climate, the less use you will get out of it, but you won't have the air quality issues with an open indoor unit.
I'm echoing Martin here. You can find a fireplace "insert". Basically a fireplace that has make-up air ventilation direct from the exterior. This way, when you close the doors to the fireplace, the combustion air is separate from the ventilation air. (the air being circulated around the unit usually with a blower fan.)
I've had success with the quadrafire 7100 (this is a big boy and even has an extra 'remote ventilation' kit that allows you to heat a different space via ductwork from the fireplace, just by switching a lever) I've had moderate sucsess with the Fireplace Extrordinaire, though it's a very fussy device, and lately I've just put an RSF Onyx 2 in one of my designs. So far so good on that one.
A "traditional" fireplace is just not very green. But I agree with your better half. I think the connection we have to open, raw fire is ancestral and fantastic, and I have a hard time dismissing it outright, just because a mechanical box can produce heat more efficiently.
Chris
The current fashion of building to Passive House standard. Avoiding heat loss by eliminating all holes makes sound sense. Provided, you have mechanical ventilation to remove the water vapour that we all create by cooking, washing, breathing, sweating etc;
This of course includes the chimney......a very large hole.
All is not lost however, as you can fit an expanding ball into the flue to completely block it, when it is not in use.
However, a fire needs air, no air, no fire.
The way to deal with this is to run a pipe (four inches diameter will do) from the outside to as close to the fire as you can get it. Under the floor, down from the attic, where ever.
Again, a ball will seal the pipe when the fire is out, when the fire is in use, it will burn cold air from outside, leaving your expensive warm air in the room.
Perfect, no nasty drafts!
Dear Interested Onlooker,
There was a community service cable TV station a few years ago that ran, outside normal programming hours, a video of a crackling fire on a continuous loop. Turned out to be a huge hit! People would just leave that channel on and have a crackling fire in the background ( I am serious about this). In a tight well insulated house the TV could also provide most of your heating needs without the fire insurance premium raising consequences that a real fireplace brings with it.
In a very well insulated and tight house combustion starts to look a little archaic; open fires are just plain primordial. The reason we started heating with fire was that it was the only option going. Buildings leaked huge amounts of heat and there was only wood and coal. I think it's about time to let go!
As someone who occasionally has to shut off his HRV because of the smoke from neighbour's fireplaces being pulled in on cold windless nights it's worth pointing out that wood smoke is hardly clean and green even if the wood stove is EPA rated.
My two cents... : )
Andrew
Nice Try Andrew.....
I do not "get" that Fire Thing myself.
I have found it almost impossible to get my clients to give up the FIRE or the GARAGE.
I have a DVD of a fireplace with crackling sound effects.
I can do without smelling like a campfire.
Andrew, the burning log is quite a popular channel at christmas and at easter where I live and your comments are quite timely considering Martin's recent blog: https://www.greenbuildingadvisor.com/blogs/dept/musings/researchers-predict-us-furnace-industry-doomed
I have to disagree with you that wood-burning is entirely un-green. Given certain circumstances, burning wood in a high-efficiency appliance is very green. Where I live I can have a tanker deliver fuel oil or I can go into my back yard and thin out a birch stand. With a super-insulated house it just means I have to cut less wood. It also means that when the power goes out I don't have to run a generator for hours (days?) on end to keep my kid's goldfish from freezing in their tank. The sustainability is very high as long as there are trees growing. Of course, as I said, this practice only makes sense because I live in the bush and not in the city.
Lucas,
Tropical fish in a cold climate are decidedly un-green.
However, I completely agree with you that there is no heat source (other than passive solar) more green than sustainably burning local wood that is harvested personally or by one's neighbors. All of the super-insulated houses I've built in the last 20 years have had woodstoves, some as their primary or only heat source (beyond free sun).
And to my friend John Brooks who said he doesn't want to smell like a campfire: there are few better cleansing agents than woodsmoke. When I lived a mile into the woods of Maine with four nuns and a priest and would go sometimes a month without a bath, people would tell me how wonderful I smelled - "just like the woods".
Now I heat only with a woodstove that often belches smoke into my little cabin and, though I bathe only once a week (when I heat up my wood-fired outdoor hot tub), I generally smell much sweeter than anyone who lives and works in a centrally-heated building.
However, Interested Onlooker, there is no place in a tight house for an open fireplace. Instead, use a fireplace insert or an efficient woodstove or get someone to build you an insanely efficient masonry heater that can also have a glass-fronted door for watching the fire.
Robert and Lucas,
I won't put up much of an argument that wood for heating energy is not green if you live in a wooded area rural and your house is energy efficient.
But I do have problems with wood when you burn it! That's where it comes out a little less clean and green.
Montreal city council has/is banning fireplaces and wood stoves because they really don't burn clean, relatively speaking.
Cheers,
Andrew
P.S. Robert: "When I lived a mile into the woods of Maine with four nuns and a priest..." There must be a story there?
Robert, you're right about the goldfish. I should probably replace them with lake trout but I'm afraid they wouldn't last very long before being eaten...
Andrew, yes, I agree wood-burning in the city doesn't make much sense. That being said, wasn't it only as far back as 1998 when that ice storm had Montrealers tearing down their neighbor's fences in a desperate attempt to keep their own goldfish from freezing?
See what I mean? Goldfish leads to vandalism. ;-)
I think folks who say burning wood is stinky or non-green have missed out on a whole section of technology called gasification. Gasification boilers, though not necessarily appropriate for this individual, are super clean-burning and very "green". Check out hearth.com before you turn away from burning wood. You just have to burn it "completely" (about 95% of the wood is burned, if using dry wood). Yes, the boilers are expensive, but they are clean and they can certainly pay for themselves quickly in certain situations.
http://garn.com/content/Products.aspx
Dear John and Lucas,
Perhaps this could move to another thread ?
Thanks to all who answered my enquiry - it looks like an insert will need to do.
I believe a good compromise would be to follow PERRY525's approach by building in a source for outside air through a pipe, as he suggested, but to also use a variable speed fan in the pipe supplying that air. I suspect that an 8" or 10" fan or two will suffice for most circumstances, including outside windiness. It'll be tricky getting the airflow coming into the house/fireplace through the supply pipe to match the airflow leaving the house through the chimney. (This is the ultimate goal, yes?) It may be possible to setup up a telltale diaphragm/membrane which will move according to the difference in pressure between outside and inside to control the speed of the fan(s) so that as the flowrate out through the chimney varies, the flowrate in through the supply varies to match, and thus maintain equal pressures. We're talking pretty small differences in pressure. Not sure if a product like this exists but I think it should. I'd buy it.
It would be wise to follow the advice of those who suggest using high-efficiency appliances. A traditional open fireplace is not a high-efficiency appliance.
If you burn wood with any frequency, removeing and inserting a balloon in the chimney will become very tedious very quickly and will probably result in the balloon not being used at all.
If you only want to burn wood once and a while then, as Martin suggested earlier, you can buy an outdoor chiminea for a fraction of the cost of a masonry fireplace.
The idea of using a forced induction combustion air system controlled by a pressure sensor makes me uneasy... though I cannot say exactly why. It certainly seems unneccesarily complicated at any rate.
We designed and built a screen room addition recently that included a traditional, open fireplace. Glass panel inserts for the screens extend use of the porch to nearly year-round, even here in Maine, with the help of the fireplace.
Interested,
Maybe this is what a previous poster meant but you can also get zero clearance fireplaces that are EPA certified and burn at fairly high efficiencies. RSF and BIS are 2 Canadian manufacturers whose products I've worked with. They have outside air intakes and sealed doors and will heat a house. The insurance companies seem to like these better than a free standing woodstove.
Thanks Donald,
That is exactly the kind of information which will help us decide what to do when the time comes to choose a wood-burning appliance. It's going to be tough - all the inserts I've seen so far are both huge and ugly. But I guess now I'm just being picky.
There are many elegant wood burning fireplace inserts available from the Scandinavian manufacturers, most meet the 75% efficient EPA tax credit level:
Morso: http://www.morsoeusa.com/5660-Standard-547.aspx
Wittus: http://www.wittus.com/wpwoodinsertmain.htm
Scan: http://www2.scan.dk/page/77?selected_id=796&idx=#796
Jotul: http://www.jotul.com/en-us/wwwjotulus/Main-menu/Products/Wood/Wood-inserts/
Jesse Thompson
Kaplan Thompson Architects
Here are the links to the 2 companies I've worked with.
BIS: http://www.securitychimneys.com/residential/fireplaces/
RSF: http://www.icc-rsf.com/en/rsf/rsf-fireplaces-woodburning-fireplaces
There are several other manufacturers as well.
Read the specs carefully for efficiency of the units you look at. While they may all be EPA certified, some produce more grams per hour of pollution than others, some burn the wood with a higher efficiency. You'll also want to look at the square footage they claim to heat, the BTU output, log length and firebox size. Some models use catalytic converters to meet the EPA Phase II specs and some don't.
Square footage heating area for a wood-burning appliance is completely worthless. How much house volume (not area) an appliance can heat depends on the heat loss from the thermal envelope, which can range from ridiculous to sublime. The only number that matters for heating ability is the BTU/hour output, and that's at optimum wood quality and maximum burn rate.
There are also plenty of high quality and efficient American-made fireplace inserts, such as Lopi and Regency.
http://www.lopistoves.com/product_guide/wood_inserts.aspx
http://www.regency-fire.com/Products/Wood/Wood-Inserts.aspx
Many thanks for the useful replies. Since the fire is for a modern new build we're particularly interested in the Morso and the BIS Nova models.