Gas Fireplace Vent

**Reis Pearson** · 03-13-2008, 06:43 AM

This is a vent for a gas fireplace that extends through a brick chimney. Technically the vent is more than 1' from the roof, but not 8' from the wall of the chimney. I've written this as improperly vented... any thoughts?

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**Scott Patterson** · 03-13-2008, 07:34 AM

Originally Posted by Reis Pearson

This is a vent for a gas fireplace that extends through a brick chimney. Technically the vent is more than 1' from the roof, but not 8' from the wall of the chimney. I've written this as improperly vented... any thoughts?

Where did you get the 8' rule from?

**Reis Pearson** · 03-13-2008, 10:04 AM

Code Check... I believe it is reference to a side wall of a building or a building opening. It's in the Mechanical section of "B" vent termination clearances.

**Scott Patterson** · 03-13-2008, 10:53 AM

Originally Posted by Reis Pearson

Code Check... I believe it is reference to a side wall of a building or a building opening. It's in the Mechanical section of "B" vent termination clearances.

I think that you are talking about IRC-2427.6.4, but that would not come into play with the masonry chimney. Now if it was the sidewall of the house, then this would be a right call. The clearances that I see look OK.

As you can not see the interior of the fireplace flue pipe, I would think that a chimney sweep needs to inspect that critter. Also it just does not look Kosher with the dings and bends in it that I can see. I would call for a Level II inspection on it.

**Bob Harper** · 03-13-2008, 03:18 PM

Unlisted masonry shroud.

**John Arnold** · 03-13-2008, 04:49 PM

Originally Posted by Bob Harper

Unlisted masonry shroud.

Who are you, sir, and what have you done with the usually loquacious Bob Harper?

**Reis Pearson** · 03-13-2008, 10:56 PM

Unlisted whosits?

**Scott Patterson** · 03-14-2008, 08:15 AM

Originally Posted by Reis Pearson

Unlisted whosits?

Bob, is talking about the masonry enclosure around the top of the chimney. It is a proprietary design and does not have any safety listing.

In other words it is a site built masonry chimney with a metal flue pipe running up the center of it!

**Jerry Peck** · 03-14-2008, 12:27 PM

Originally Posted by Scott Patterson

Bob, is talking about the masonry enclosure around the top of the chimney. It is a proprietary design and does not have any safety listing.

In other words it is a site built masonry chimney with a metal flue pipe running up the center of it!

Close, Bob's only referring to the top part above the inside lower cap (I think that's what Bob is referring to), the part with the openings and up.

Looking at the photos, that looks like a masonry chimney, lined with a flue liner, with some handmade/homemade flat base blocking most of the flue liner and transitioning to a smaller cap.

Being as Reis said "This is a vent for a gas fireplace that extends through a brick chimney.", I'm suspecting that it was a wood burning fireplace which has been converted to gas.

Would be nice to see photos of the fireplace and its damper, etc.

**Reis Pearson** · 03-14-2008, 12:46 PM

I wasn't able to view the damper or the connection, it was an older insert (see photo).

**Bob Harper** · 03-14-2008, 06:50 PM

See the pic showing the liner cap? See the mortar crown wash with the flue tile protruding up? That's the top of the chimney. It does not appear to have the requisite 3 feet above the roofline as measured on the uphill junction with the roof to the flue gas outlet.

Now, they installed a liner, probably aluminum 4" for the gas fireplace insert. If this is a single liner then the fireplace is categorized same as a Cat. I B-vented unit. Look for a rectangular draft hood opening at the top of the unit behind the upper grilles in that brass front. It would be nice to know if that front is listed for that unit or not.

All the brick columns and slab top are essentially a "shroud". Since it is site built, it cannot be listed for use with that liner, thus it is illegal. It would make a nice wildlife habitat. If there is a shared flue in there, it will predispose it to recirculating flue gases back down the other flue, esp. if it serves a fireplace in the basement.

I would recommend that brick shroud be removed so that liner can breathe then have a qualified tech service that poor insert. Look at how cloudy the glass is. Probably has not been serviced in years.

That mo' better John?
Bob

**Terry Beck** · 03-15-2008, 10:01 PM

About the fog inside the glass front -
Reis didn't say anything about that, whether it was there when he arrrived, or if it appeared while he was testing the gas insert. I do know that when I test a gas insert or fireplace, I very commonly see the inside of the glass fog up for a few minutes if the fireplace was cold. It is usually just some condensation forming when it is first turned on, and will disappear in 5 minutes.

**Bob Harper** · 03-16-2008, 12:54 PM

Terry, you are correct that virtually all gas fireplaces with glass fronts will fog up when first fired. However, I did not see flames in the photo presented and the color and pattern of the haze is more consistent with the white film gas fireplaces get. When the glass fogs up, the entire glass will fog, then, a patch will clear in the center, usually down low and spread outwards.

If the glass is maintained properly, this film can be removed using special products made for it such as White Off by Rutland or Brasso or Noxon metal polish. You must grind away with a soft clean rag--wax on/ wax off.

If the film has been allow to set for a year or more, they'll probably have to replace the glass as it sets into the pores of the glass and cannot be blasted out.
HTH,
Bob