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mark2741 12-10-2010 04:01 PM

Cold Air Coming In From Bottom/Underneath of Gas Fireplace Insert
 
We bought a house earlier this year that has a family room addition with a brick fireplace. The previous owner had a contractor put in a gas insert.

This family room addition is always colder than the rest of the house, which surprised me because in the summer the air conditioning (central air, fed through same floor registers/duct as the gas furnace heat) was excellent in this room - plenty cold.

Today, I went to hang the family's christmas stockings under the fireplace mantle and felt a lot of cold air hitting my legs. After inspecting, I realize that the reason this room is always colder than the rest of the house is because there is a ton of cold air coming in underneath the gas fireplace insert! See image:

http://elearninglive.com/temp/images/IMG_3631.JPG

It seems that the gas insert's enclosure bottom must sit off of the bottom of the fireplace opening by about an inch. I'm guessing that that, along with a void between the back of the insert and the flue, is allowing cold air to come down the chimney, past the back of the insert, and underneath the insert and out into my family room : (

How can I fix this? Is this a DIY job? Can I simply insert some insulation/spray foam? Or do I need to call a chimney guy?

Here's a photo trying to capture/show the approximate 1" gap under the insert where the air is coming in. It's the part where the electrical cord is laying, and has all the cobwebs.

http://elearninglive.com/temp/images/IMG_3632.JPG

mark2741 12-10-2010 04:11 PM

One other thing I wanted to add -

We never keep the pilot light on. I just assumed it was wasting gas unnecessarily and since it is easy to light this fireplace up we always turn it off. I just read that leaving the pilot light on might help so I'll give it a try, but the pilot light on this insert is pretty damn big (though I've never seen/had a gas fireplace before so I don't know if it is abnormally large). It's about 2.5" x 1.5" - a lot bigger than the 'pilot light' I recall seeing as a little kid in the stove : )

diyorpay 12-10-2010 05:32 PM

Not an expert here.

Fireplaces often had a cleanout trap in bottom of fireplace covered by a metal piece (false bottom). Cleanout is on opposite side of fireplace (in my case, in the garage). If you have one, is yours: uncovered? Door on opposite side open?

If you find this so, maybe put insulation into this config, since you don't need to gather embers etc?

Odd_Guy 12-10-2010 06:36 PM

Not my area of expertise, but I've looked at a couple. Try removing that grate at the bottom and look under there. Sometimes the electrical or gas are run in through larger knockouts than needed (it's easier to do) and then not sealed up. Some expanding foam may help, but read the labels. Too much expansion can cause damage.

One I looked at was all properly sealed and insulated, just needed the pilot light on to not feel cold.

Hope that helps.

Hixheat1 12-10-2010 06:54 PM

Quote:

Originally Posted by Odd_Guy
Not my area of expertise, but I've looked at a couple. Try removing that grate at the bottom and look under there. Sometimes the electrical or gas are run in through larger knockouts than needed (it's easier to do) and then not sealed up. Some expanding foam may help, but read the labels. Too much expansion can cause damage.

One I looked at was all properly sealed and insulated, just needed the pilot light on to not feel cold.

Hope that helps.

You are drafting from flue is it vent free. Insulating under fire place will not stop drafting, if it is is a vented set of logs the only thing you can do is close the damper, there should be a damper stop to prevent from closing all the way do not remove stop. If vent free you can seal the flue. See owners man. For safety limitations.

Hixheat1 12-10-2010 07:00 PM

Quote:

Originally Posted by Hixheat1

You are drafting from flue is it vent free. Insulating under fire place will not stop drafting, if it is is a vented set of logs the only thing you can do is close the damper, there should be a damper stop to prevent from closing all the way do not remove stop. If vent free you can seal the flue. See owners man. For safety limitations.

From what I see in the pict they are vent free the combustion air comes from bottom. The best way to seal is to pull insert out and seal flue top and bottom this will prevent drafting. I do recommend if you do seal don't make it perm. You may want too sell some day and som people like a functioning fireplace. Ps insulate bottom plate.

mark2741 12-10-2010 09:29 PM

Thanks guys. I did some googling after my original post and it seemed a lot of the solutions were to simply leave the pilot light on, so I tried it. A few hours later I went into the room and put my hands at the bottom and, sure enough, no draft whatsoever - just room temp air.

Not sure why it worked, but it did. So, I guess I learned my lesson - to leave the pilot light on during the winter.

Hixheat1 12-10-2010 10:05 PM

Quote:

Originally Posted by mark2741
Thanks guys. I did some googling after my original post and it seemed a lot of the solutions were to simply leave the pilot light on, so I tried it. A few hours later I went into the room and put my hands at the bottom and, sure enough, no draft whatsoever - just room temp air.

Not sure why it worked, but it did. So, I guess I learned my lesson - to leave the pilot light on during the winter.

The pilot warms the chimney so the cold air does not transfer into your house and keeps the draft going up, so it pulls the air from inside the house to the flue. I turn my pilot off in summer.


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