Plug My Vent Free Gas Log Chimney

Q: Jason, I have a set of non-vented gas logs which when not in use lets a horrible downflow of cold air in from outside. I saw an old thread that said the Chimney Balloon will deflate when installing near the damper if it is exposed to heat.

My question is can I close off the top of the chimney chase up on the roof with one of the Chimney Balloons? And would the temperature at that height be cool enough where we could fire the gas logs and still keep the Chimney Balloon intact? Thanks, DV

A: Hi DV, You pose a very good question. We have had many customers install a Chimney Balloon upside down from the top of the chimney when they have installed an electric fireplace insert, or if they have decommissioned their fireplace completely, but I have strong reservations about trying it with a vent free gas log.

My initial reaction is with the vent free gas log burning I am certain that the temperature at the top of the chimney will get to the 200 degrees Fahrenheit and trigger the Chimney Balloon to melt, shrink, and release. The reason for my certainty is that the damper you have is inevitably going to leak heat or convect heat into the chimney and that heat will naturally rise and collect against the Chimney Balloon.

My suggestion is to use the Chimney Balloon conventionally and just install it while the fireplace is not being used. Any amount of time you have the Chimney Balloon installed will be saving you money.

There is one other thing you should be aware of with your vent free gas log. There was a University of IL 3 year study that was done on ventless gas units in homes in Illinois. Here is a link to a blog article about the study and a link to the study results:

Personally, I found this research to be eye-opening and something that ventless gas log users should be aware of. I will let you draw your own conclusion from it, but pay particular attention to the NO2 level results in the study.- Jason