What do you think is causing the inside of the glass on this direct vent fireplace to fog? Poor venting? Pilot was lit, it vents directly out the back to the exterior.
Thanks, Steve
Water is in gas. The condensation is a by product of combustion. It will probably disappear when the burner is ignited.
Did you try the burner?
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Yes, and it fired up. I did not run it long though. Were you gonna say after leaving it run a while the fog would go away?
Thanks, Steve
Yes, once the fireplace heats up the moisture should go away.
It’s more than moisture.
Be right back with great info for you.
Here you go:
There’s also a picture in the very first post in that thread.
Sometimes the link doesn’t work; tonight it did.
Yes, good info Russel. It may be that, however I’ve noted many fireplace glass fronts that cleared, what appeared to be moisture, after it was heated up. These were all pilot lighted units I’m talking about. I had one for years that acted that way and never damaged the glass. It always cleared.
They do clear up. I’ve never seen one that didn’t clear up. However, the damage from the sulfuric acid remains, even though it might, indeed, take years before the damage is noticeable. It depends on the quality of the gas and how often the fireplace is used.
I had a one-year-old house a couple of weeks ago that had a direct vent fireplace. When I flipped on the switch, the glass fogged up and the Client got upset. We let it burn awhile and I showed her the damage that had already been caused by the sulfuric acid. They have requested from the seller a new glass front for the fireplace. Our gas out here is pretty oogy.
Yes, that may be it.
I’ve heard that about more things than gas in CA. :mrgreen:
By the way, if anyone ever has an opportunity to attend a seminar by Dale Feb, one should jump at the opportunity. One will never look at, or think about, fireplaces and chimneys the same way again. They are eye-opening seminars.
My problem with condensation on the glass of my gas fireplace is different than discussed so far. I have condensation on the glass all the time, not just when I turn it on. It is humid where I live, The fireplace company who installed it said I should turn it on to clear the glass. This is not a solution because I would have to have the fireplace on all summer to keep the condensation away. It is directly vented to the outside wall behind the fireplace and the glass can be removed for cleaning. Any suggestions about how I can prevent this? I’ve turned the temperature in the house as high as is comfortable and it is still a problem. Any suggestions will be welcome. I would be willing to do something that would make the fireplace inoperable either always or for most months of the year.
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Do you keep your pilot light lit? It tends to help.
The process of burning natural gas produces moisture that has a high level of sulfuric acid. That acid etches the glass, making the foggy appearance permanent.
Thank you. I don’t now whether I have a pilot light or some kind of electronic igniter.
It is directly vented to the outside wall behind the fireplace. Is there a way to insulate that vent better or block it with insulation during the summer to prevent this problem. It is not sealed u
The fireplace company which installed it suggested I turn the fireplace on for 10 to 15 minutes to remove the condensation. I did that, but the condensation was back in about 5 minutes. This can’t be the answer since I’d have to have the fireplace on all summer. I’ve raised the temperature in my house, but that didn’t help. There is condensation on the fireplace glass all of the time.
Any suggestions will be greatly appreciated. You are so kind to give your expert advice to people who need it.
Deborah Pedersen
Often those direct vent do not have a damper. IMO, warm damp exterior air comes in contact with cool glass causing condensation. It is a design issue apparently. However, yours sounds pretty extreme.