Gas Fireplace Venting Problem

[warehouse]

So I have a gas log fireplace which was converted some time ago from a wood burning brick fireplace. During the conversion, a liner was installed inside the existing brick structure all the way to the top (2-stories). I wasn't living in the house at the time so I'm not sure if this has always been a problem but now every time I use the fireplace I get a strong exhaust smell in my house unless I keep the glass doors shut during operation. As this defeats the purpose of the fireplace for heat purposes I would rather be able to use the fireplace with the doors open. I tried lighting a couple of peices of newspaper and watched the smoke. For the most part it looks like the smoke goes up the chimney but I did see some roll back of smoke towards the front of the fireplace. I have a feeling that the fireplace is not drawing properly. Does anyone have any ideas how I can correct this? I do have an access panel about 8 feet up the chimney. Would it be possible to vent somehow from there instead of requiring the exhaust to travel up two stories?

I also tried moving the log set back in the fireplace but that didn't seem to make much difference either. Also, I did have the flu open!

Any ideas would be greatly appreciated!

 

[webbie]

Not sure exactly what you have. Was it a masonry fireplace originally or a prefab?

Is it simply a set of gas logs installed into a fireplace? Or some kind of insert?

Pic might help.

In general, chimneys are not relined when gas logs are installed, so that is throwing me off. Do you know the size ID or the liner?

 

[STOVEGUY11]

If its a vented log set, you are not suppose to get any heat out of them. Just for looks. If its a vent free set, you are suppose to burn with the dmper closed, and that is one of the drawbacks. The combustion smell.

 

[warehouse]

Thanks for the replies. Sorry that I didn't provide all the details up front!

While I was renting out my house, I was told by a chimney sweep that my wood fireplace had cracks in it and needed a liner. I decided at that time to just convert it to gas instead of dealing with the wood. They installed the liner and the gas logs. I was told that the fireplace should be vented (flu open). It's not an insert, it's masonry.

So from the earlier post am I to assume that this is just decorative and I should just leave the glass doors shut and enjoy the view but not the heat?

I've attached a photo.

One other quick question. Does the flu need to remain open when the pilot light is on, or just when the whole fireplace is on?

Thanks!

 

[STOVEGUY11]

Yes the damper remains cracked open when the pilot is on unless it has electronic ignition. Also, when you burn the logs, you need to have the doors open. Otherwise you could destroy the doors. Glass doors are typically tempered glass, not pyro-ceramic.

 

[warehouse]

Well that's my problem. If I leave the glass doors open then I get the horrible smell. If I close them and leave the vent at the bottom of the doors open then I don't get the smell but I don't get any heat. But now you're telling me that might be bad for the doors. Right now I just don't use it, which is a waste! Maybe I'll try to get a professional to come out and take a look and give me some recommendations.

 

[jtp10181]

I would recomend a gas direct vent insert. Something like this: http://www.heatnglo.com/products/inserts/gasInsertDetail.asp?f=07900

They are a sealed system, bring fresh air down and exhaust back up. This is the easiest fix for a wood fireplace (or gas log) that wont draft correctly.

 

[webbie]

Well that's my problem. If I leave the glass doors open then I get the horrible smell. If I close them and leave the vent at the bottom of the doors open then I don't get the smell but I don't get any heat. But now you're telling me that might be bad for the doors. Right now I just don't use it, which is a waste! Maybe I'll try to get a professional to come out and take a look and give me some recommendations.

I'm sort of amazed that they relined the chimney and then installed gas logs. Most chimneys are fine for installing vented gas logs in - a few cracks are usually found in any masonry flue and should not hurt the gas longs.

BUT, they now lined the chimney and may have vastly downsized the flue in the process. Do you know what size pipe they used to reline the chimney? Making it ANY smaller will create the exact problem that you mention - that the fireplace now does not draw correctly. After all, you have to consider that the size of the chimney as built originally matched what was needed for the firebox size.

In short, if the chimney liner is not at least 8" round - or, better yet, 10" round (which is typical for an open fireplace relining), then you may have problems.
If you can get
1. The width and height of the front of the fireplace opening
and
2. The size of the liner

Then I can give some more tips and hints to fix it.

 

[warehouse]

The opening is 32" high by 36" wide and the depth is about 26". It angles back and the rear wall is about 24" wide.

I was renting the house out a few years ago when the work was done and I remember that they said that they did some kind of thermal imaging and found these cracks and that there was a danger of exhaust leaking into the living space in the upper floor of the house. This is why the liner was installed. This structure supports the fireplace on the main level as well as the MBR fireplace on the floor above. I also know that they told me that this liner is not approved for wood burning. I don't know if that was because of the size or material. I can't reach to measure it but the liner looks to be at least 8" if not 10" in diameter.

Thanks again for all of the help!

 

[webbie]

Interesting, because it is very rare to line an existing open fireplace chimney with the non-woodburning type of liners - these would be aluminum. In fact, to my knowledge, this was not even legal to do because the gas logs are specified to be installed into a wood burning fireplace and chimney only!

The two possible materials for a liner are stainless steel and aluminum. Stainless steel would be good for wood burning, aluminum would not.

Onto the draft situation...in order to draft properly, a flue should be approx 1/10 the size of the fireplace opening in square inches. Sometimes you can get to 1/12. So your opening is 32x36, or approx 1152 square inches.......so the chimney should be at least 100 sq inches. An 8" round is about 55 square inches and a 10" round is about 80 square inches, so as you can see the chimney is not really capable of always venting that size of an opening.

The easiest solution is to lower the effective height of the fireplace opening by 6 inches or so using a piece of sheet metal (can be painted), which might fix things.

 

[jtp10181]

If the liner is not approved for wood burning then having the gas log in there is also technically not allowed. Vented Gas logs must be installed into a fully functioning and approved wood burning fireplace.

 

[warehouse]

hmmm, I'll have to see if I can find my paperwork to see if there's any kind of notation indicating whether it's approved for wood burning or not. It's been a few years so I can't really remember all the details, but I thought that they told me that because of the liner they used, it was not approved for wood anymore.

To me the liner looks like aluminum rather than stainless steel, but looks can be deceiving.

So looking at this again, technically the opening is only 24x36 because of the frame that surrounds the glass doors, versus the 32x36 of the masonry work. That still puts it at 864 square inches which is still too large for an 8" liner. I'll try to go out to the access panel tomorrow and measure the actual liner diameter and construction material. I'll also try operating it with only one door open to see if it draws properly. That should make the opening small enough for the smaller liner.


So if this is not up to code (aluminum, too small, etc.) do I have any recourse with the installer after 3-4 years?

 

[webbie]

If the installer is reputable and actually installed aluminum you should ask him about both the opening size and the fact that gas logs are only approved for use in an actual wood burning flue....see what he says. I would be interested.

FYI, I don't think that part represents a big danger, but it could in the future as a buyer is likely to remove the log set and burn wood. The aluminum can hold up to the gas log temps, etc.