Spray foamed house and ventless gas fireplaces
Donny Holmes| Posted inGreen Building Techniqueson
I have a few friends building a house and both are using spray foam to insulate with. They are also wanting to install vent-less gas log fireplaces. I have done a little research but haven’t found much on it. Is this a good idea? Any help on this is appreciated.
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Replies
Ventless fireplaces are really bad for indoor air quality. They are even worse in a tight house.
No, it's a bad idea. Anything "ventless" for combustion appliances is a bad idea regardless of how you insulate. "Ventless" means all the combustion byproducts (and there are always some) go into your home. "Ventless" also means the combustion air (primarily oxygen) is drawn from the air inside your home. This is a Bad Thing.
I would absolutely NOT use ventless gas anything inside a home, ever. If they want gas log fireplaces, get the kind that are sealed from the home, and have their own, separate air supply and exhaust to the outdoors. Those are much safer.
BTW, while it's not to your original topic, there are a lot of ways to insulate without spray foam that in many ways will do as well, or even better than, spray foam at less cost. That might be something else to discuss with your friends.
Bill
You might ask them to watch our recent BS + Beer Show on the subject:https://youtu.be/sVnE_56xYCU. As Steve and Bill said, ventless combustion appliances are never a good idea, and spray foam really shouldn't be necessary and brings its own set of risks.