cold direct vent

mleesebergFebruary 8, 2007

I have a Heatilator direct vent that was part of our new house built last fall. This past weekend, it was 0 degrees outside, 3o degrees at the hearth and 22 in the lower box of the fireplace.

Builder and Installer say this is normal for all direct vents, as the flue is always open to the outside. I think it doesn't sound correct. It is installed in a bumpout. I know the back wall and sides are insulated and drywalled. But, the deck/hearth it is sitting on, not sure that is insulated.

Looking for any advice here.

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Unfortunately, your builder/installer are both correct. Since the firebox is continuously exposed to outside air via the coaxial combustion/exhaust air pipe, you'll always have outside air present. Had I known what a heat loss these supposedly "efficient" direct vents are, I would have never had one put in our new house last year. Of course the dealer will never point this out. If I could do it over again, I would have a traditional masonry fireplace witht the flue capped shut and just put a vent-free gas log set in the firebox.

    Bookmark   February 9, 2007 at 8:58AM
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We've had the very same experience with our new house/fireplace and I came to the same conclusion as you, that the bottom of the bump-out wasn't insulated. The cold air isn't in the firebox itself, it's coming in around it--especially the bottom.

I don't know if it really is normal. My parents have a similar set-up and while there is some coolness and drafts, it's not like there's an open window in the living room (which is what ours feels like).

Please post if you come up with any new information--I'll do likewise, because it really isn't acceptable as-is!

    Bookmark   February 27, 2007 at 11:41PM
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We have the exact same problem. We had someone come out to look at it and unfortunately they were not very helpful, but they did say it might be the type of unit, but after reading your posts now I'm not so sure. We have a heat-n-glow direct vent...not sure the model though. It was put in by the builder. I was going to go out to a local fireplace dealer and see if they think replacing the unit will do any good. We are not using our fireplace at all because we had to stuff towels in it to prevent the draft. It felt like there was a window open in the family room. Definitely not acceptable, but I hate to have a fireplace and not be able to use it. Please let me know if you figure out a solution. I will do the same.


    Bookmark   March 3, 2007 at 4:19PM
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the firebox and the venting are sealed from the "shell" the firebox is built in. You would have to have air leaving the fireplace for fresh cold air to be coming in the vent. When the fireplace is off no air should be leaving the firebox and no air should be entering the firebox.
once agin, this is a "sealed combustion chamber" usually cold air coming out of your fireplace is a installation issue. If this were not true, then NO ONE would be happy with there direct vent fireplace, and trust me there are lots more happy customers in cold climates then not.

    Bookmark   March 3, 2007 at 5:13PM
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I agree this issue must have something to do with the installation. I have DV and no draft issues (thankfully because I live in minnesota).
FYI. Mine is NOT installed with a bump-out.

    Bookmark   March 3, 2007 at 7:36PM
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stephsxty9 yours installed on an outside or inside wall? Mine is installed with a bump-out and I am trying to see if anyone has a bump out that does not leak air when not running. I'm not sure if it is an installation problem or a bad design in the fireplace itself.

    Bookmark   March 3, 2007 at 10:05PM
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that absolute cheapist, worst designed direct vent fireplaces should not have cold air coming out of them. The sealed combustion chamber is always seperate from the box you frame in. If you have cold air coming out of the bottem vent, there is no way that is coming from the combustion chamber, and the combustion chamber is hooked up to the flue. The flue is not what is causing the cold air to come in the room, Its coming from the chase that that fireplace is installed in, and its 100% installation issue.
one possibilty would be this:
the pilot assembly penetrates the bottem floor of the fireplace into the cavity that houses the valve. This penetration is usually sealed with red hi temp RTV, if the penetration is sloppy and not sealed then some cold air could get in that way. This usally happens when a homeowner replaces the pilot assembly and doenst re seal it properly, or the guy on the line at the factory had a few beers for lunch and forgot to seal it properly.

    Bookmark   March 4, 2007 at 11:36AM
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I have to agree with MSG its a very poor installation. The cold air is not leaking where everbody thinks it is. They all claim the walls and floor are insulated right? So where else cound it be comming from? I'm an inspector and I can tell you the walls and floors are insulated but for some reason the top of the chace alcove ceiling gets neglected and not insulated. I had on installed claim he does not have to insulate the top because it would create a heat sync another one told me the top ceoling should not be insulated to allow the unit to dissipate heat, Both BS answers so I told both that my signature requires insulation. Since you are not looking there you assume it must be the unit or draft system that a closed combustion system. What is happening that cold air sinks to the bottom where you are feeling it that uninsulated ceiling cools the entire prefab
naturqlly the coldest place being where it settles the floor. U You can swap out units and everyone will be cold and have the same problem If the chace or alcove bumpout were built correctly it would be 5/5" fire coaded sheetrocked taped and seamed as well as being insulated including the ceiling built correctly you would not he having this problem What probably is the current state is bare studs with insulation bats inbetween These bats unless installed correctly and fitted right also will also produce cold drafts. So there are 3 potentail defeciencies poor insulation placement no 5/8" s taped ansd seamed sheetrock and un insulated ceilings without sheet rock. I agree with the MSG guy the chase is the issue

    Bookmark   March 4, 2007 at 12:07PM
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Thanks. I'll let you know what we end up doing. --Steph

    Bookmark   March 4, 2007 at 10:08PM
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How is combustion air supposed to be kept separate from the exhaust? I think my DV has a coaxial intake/exhaust pipe. Is the burner sealed somehow? There is also a penetration below the firebox for the corrugated gas line pigtail that should be sealed.

    Bookmark   March 5, 2007 at 9:16AM
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for what its worth, mine is installed on the outside wall.

    Bookmark   March 5, 2007 at 10:11AM
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the pipe is coaxial, the fresh air enters the firebox via the outside pipe, and the combustion flue gas exits through the center of the pipe. Any and all penetrations from the firebox to to the control area should be sealed.

    Bookmark   March 5, 2007 at 2:00PM
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I just went through this as well, and spent the day on Sunday removing my fireplace myself to see just what was going on. What I found was rather shocking, and certainly made the problem crystal clear. I have an EnergyStar rated home and was amazed that the house could pass the negative pressure test with the amount of cold air coming in. Previously, I complained to the builder who had the fireplace people come back and they installed some Roxul high temp insulation from the outside, did little, if anything.

When I removed my fireplace I found that everything was done exactly as the building code requires here in Canada. Doesn't mean it's right, just that it meets the requirements.

Behind the fireplace there was insulation and vapour barrier as required, but where the fireplace vent sleeve passed through the wall, there was absolutely nothing sealing it to the exterior wall, in this case pink sheet styrofoam and brick. I placed a silicone bead around the vent sleeve and air leakage dropped a lot. Second issue was fireplace is in a bump out and it needs to be vented so the shingles don't melt. The cold air was coming in from the top and leaking down behind the vapour barrier. Since there is no drywall, there is nothing applying pressure against the vapour barrier and the studs. With only a few staples holding the vapour barrier in place cold air was pouring out the bottom. I removed all the vapour barrier, applied a bead of accoustical sealing to all the stud surfaces and a bead along the floor and replaced the vapour barrier. Also used tuck tape on any nick or cut I could find.

Lastly, I installed a small piece of wood strapping along the floor, at the top, and on the sides of the cavity to compress the vapour and accoustical sealant to provide a long-term fix.

I have not had the gas line re-connected yet and the temperature plummeted here last night and today and without even the pilot running we can now comfortably play with our children in front of the fireplace. Previously, the cold air coming from under the unit would blow balloons five or six feet out from the fireplace.

Builders are doing all that is required, they are installing the vapour barrier in that space the same they would any where else. If you are not handy and willing to pull out your fireplace I don't know how far this will get you with your builder but I do plan on at least writing a letter to mine with my findings. A little extra effort would go a long way in providing years of comfort.

Good luck.

    Bookmark   March 19, 2007 at 9:45PM
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So it was the installation and not the fireplace itself?

    Bookmark   March 20, 2007 at 7:46PM
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I believe the answer would be yes - installation. They have been making direct vent fire places for a while now and if it was a fireplace problem they would not be selling.

Almost all problems I have heard about cold air leaking has been installation problems.

Here is a link that might be useful: Rod & DJs House Building Adventure

    Bookmark   March 20, 2007 at 11:03PM
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jason--Thanks for the detailed info on your FP repair. Was your air leak coming from the FP controls area beneath the firebox, or from some other location outside the outer metal skin of the FP? The reason I ask is I don't understand how air leaking from the bump out structure through the vapor barrier can get through the outer metal skin of the FP itself. Thanks.

    Bookmark   March 21, 2007 at 9:39AM
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there are severl knock outs in the bottem control area to the external firebox. The gas line has to penatrate the firewall and so does electrical. thats where the air get in.

drafty DV fireplace = leaky bump out.
Not to uncommon if there thrown in.

    Bookmark   March 21, 2007 at 11:24AM
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A note of gratitude. My house was built in 2001 with a new gas fireplace installed. We are on pilings in a very windy area. Once the winter arrived, cold air from the fireplace would come rushing in. Periodically, I would go the the fireplace company and explain the situation and was told nothing could be done about it. Finally, I got on this site and read all of your postings which inspired me to go one more time to the store and ask if anything new had been devised to correct this situation. Only this time I showed your postings and asked that an installer come to my home to inspect the fireplace. At that time, the salesman said it was most likely an insullation problem and maybe it could be caulked. After the service man inspected my problem, I was so disheartened when he said the cold air was a lack of insullation because I thought nothing could be done about it. He explained that this is an older model which has extra holes at the bottom (their current model only has 2 - one for electric, one for gas) which is allowing cold air to enter. He took some insullation out of the open walls I had in my storage area and plugged up all the extra holes and BAM-just like that-no wind. I am currently enjoying my fireplace for the first time.

    Bookmark   March 23, 2007 at 10:48AM
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I finally had the builder out this spring, they opened up the bumpout. Guess what, there was drywall but no insulation sitting on the horizontal piece above the fireplace box. So, all the cold air was just sinking onto the box and coming in.

Goes to show you, use common sense and make them follow-up. It took almost 18 months to resolve the issue I suspected from the start, this is after a "Certified, union HVAC" guy came out.

    Bookmark   July 12, 2008 at 10:26PM
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I have a gold-& Glow direct vent fireplace, installed by the "dealer experts". Feels like a window is open is a good description. I read the other comments to say the firebox is sealed to outside air however that is not how this fireplace is designed and made. It is made with a large gap around the burner assembly between the firebox and the vent space below the fireplace. The vent space is open to the inside room so warm air from the room easily drafts out through the gap into the firebox and out the flue. In its place comes rushing cold air from outside. It's the most ridiculous design I can imagine. Never buy one of these things. Insulation around the unit does nothing to fix the problem It's the direct access to room air to escape through the flue that's the problem. Take the log set out and look for yourself.

    Bookmark   January 12, 2013 at 9:09AM
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So what is a good brand/model to buy? Obviously it sounds like you have to watch the install but would you guys still buy the same fireplace or go a different route?

    Bookmark   January 24, 2013 at 8:32PM
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I have a direct vent natural gas fireplace made by Monessen.

I hate it.

I have the same cold direct vent problems. There is a breeze coming through the bottom vent, and the floor temp there was 47 degrees last night.

The builder who installed it seems puzzled, and I got the same "that can't be - it's all sealed up in there" answer.

The builder does seem willing to keep investigating, but at this point I hate that fireplace and wish I'd never had it installed.

    Bookmark   January 25, 2013 at 10:09AM
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I was intrigued to find this post here as we have a Heat and Glo direct vent gas fireplace which proves very cold in winter here in MN.

Upon removing the vent ducting this week I discovered what a shoddy installation job a previous homeowner (who, incidentally claimed to be a "contractor") did on this. It is no wonder that the entire enclosure gets a ton of cold air in winter.

My thought is to build a box out of 2x4 framing in the wall around the duct, as the manufacturer instructs you are supposed to, sealing it to the exterior sheathing and interior lathe as best I can with caulk/expanding foam.
I also intend to do a more proper job of securing the duct cap to the exterior of the house by fastening it to the exterior sheathing, caulking thoroughly, and properly finishing the vinyl with j channel.

Does this sound like a reasonable solution, or is there more I can do to seal it?

Also, does anyone have experience with the gap between the firestop plate and the back wall of the fireplace insert (highlighted in my photo with green)? Should there be such a big gap there and if not, are there any solutions to this defect?

Sorry for the incomplete post..more photos to come shortly

Thanks for the help!
Dave in MN

Here is a link that might be useful: Photos of what I discovered during the disassembly and a proper install example

This post was edited by davetz1 on Fri, Jul 11, 14 at 20:49

    Bookmark   July 11, 2014 at 5:32PM
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