Ventless Gas Furnaces
LESLIE: Tom in West Virginia is thinking about a ventless gas fireplace, which is not always a great idea. What’s going on? How can we help you?
TOM IN WEST VIRGINIA: Yeah, having survived another winter, and in expectation of another one coming up, I have a rather older system with the eight-inch exhaust pipes that comes off the furnace and I wanted to replace that and my neighbor has something that he calls a ventless gas furnace but actually there’s a vent that comes right out the side of the house like a dryer vent. But online I saw reference to a gas furnace that’s ventless and I’d like to get your idea of what the good, the bad and the ugly is over one of those.
TOM: Well, we don’t recommend ventless anything. I’ve never seen a ventless gas furnace. I mean there may be a very small ventless gas heater but …
TOM IN WEST VIRGINIA: Yeah.
TOM: … not a ventless gas furnace. What you’re describing, that your neighbor had, is known as a direct-vent furnace …
TOM IN WEST VIRGINIA: OK.
TOM: … and many of the high-efficiency furnaces do just that. You know, we’re used to seeing furnaces that vent into big, brick chimneys that take all of those heating gases up to the top of our house and away.
TOM IN WEST VIRGINIA: Yeah, that’s what I’ve got.
TOM: But the high-efficiency furnaces, the reason they’re called high-efficiency is because they take so much of that heat out of that exhaust gas and use it for your house that the gases that are left are relatively low-temperature and that’s why they can be direct vented out the side wall of your house through, sometimes, plastic pipes.
LESLIE: Yeah, or even if you’re going to continue venting through your chimney you need to then line it because it’s such a difference in temperature that now you’re dealing with condensation.
TOM: That’s right and the condensation is very corrosive. So high-efficiency gas furnaces are great. We do not like unvented anything. You know, unvented gas furnaces, never heard of it; but unvented gas fireplaces we hear a lot about and absolutely don’t like those.
TOM IN WEST VIRGINIA: (chuckling) I appreciate that.
TOM: Too much moisture inside the house, Tom.
TOM IN WEST VIRGINIA: Thank you very much.
TOM: You’re welcome. Thanks so much for calling us at 888-MONEY-PIT.