Thread: Woodburning Unit Converted to Gas

I saw a manufactered wood burning fireplace that had been converted to a gas unit with ceramic logset. The damper door in the fireplace was not altered in any way and could still be completely closed or completely opened. Isn't the damper door supposed to be changed to a fixed open position when a wood burning-to-gas conversion is done?

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Nick, what is the brand fireplace and what ANSI Std. was on the rating plate of the logs?

It may be ventfree gas logs, which do not require the damper to be removed or blocked open. However, some mfr.s such as Heatilator/ Heat&Glo use the chimney for cooling the box so blocking the damper could burn the house down. Therefore, they expressly forbid the installation of VF logs into their fireplaces. There is an optional section of UL 127 where a mfr. can test their factory built Fp for use with 40,000 BTU VF logs. Majestic is one mfr. who does it and state they don't have a problem with any brand VF logs in their Fp as long as they are 40 mbtu max.

Need to record those rating plates.

I knew you would have an answer Bob. I of course have non of the spec info you stated.

I am quickly discovering the amount of info I know about fireplaces is nowhere near enough.

Is there any circumstance where a gas unit is present where blocking open the damper would do harm? I recognize the potential energy loss.

I thought that the damper should have a device installed to prevent it's closing if gas logs are present and have been writing it up as such. If you are concerned about energy loss, the doors could be upgraded which should probably be done anyway to help prevent CO in the home.

I know that with the perfect cobustion that the vent free logs should employ CO is not a concern, but how long does "perfect combustion" last and when will burner adjustments be needed.

I also recommend CO detectors be installed in the home whenever gas appliances are present, especially fireplaces.

Thanks John. My question though is if there are any situations where keeping the damper blocked open could do harm? I am not aware of any, but then again, the longer I do this the more I am aware of that I am not aware of.

Bob,

How can an inspector determine if a log set is intended for VF operation. Will the tag state so?

Originally Posted by Michael Thomas

How can an inspector determine if a log set is intended for VF operation. Will the tag state so?

I'm not Bob, but yes, the tags will state that.

Originally Posted by Thom Walker

Thanks John. My question though is if there are any situations where keeping the damper blocked open could do harm? I am not aware of any, but then again, the longer I do this the more I am aware of that I am not aware of.

I don't know of any actual harm that might occur. Make sure that there is a vermin screen on the chimney cap to prevent birds, squirells, etc. from gaining entry. Keep in mind that not every fireplace has a damper.

Jerry P is pretty knowledgable about most issues, and he has posted to this thread already. I'm sure that he would mention it if it were an issue.

"
Is there any circumstance where a gas unit is present where blocking open the damper would do harm? I recognize the potential energy loss."

The only thing I can think of is what you mentioned - energy.

Most ventless gas logs make good heaters, because they do not lose their heat up the vent. Vent one and you lose that heat up the vent just like with a vented gas log set.

Does venting a ventless gas log set make it a vented gas log set? No. It just means you have a vented ventless gas log set.

Does that mean the listing and labeling has been violated (being used not in accordance with its listing and labeling)? Not the ones I remember seeing, which all had a 'vent option', if one so chose.

Bob H. would have more specific information on this than I do.

If you look at the ANSI std. on the rating plate to which the unit is tested and listed, it will tell you what you need. A ventfree logset is listed to ANSI Z21.11.2a or b
a vented logset is listed to ANSI Z21.60.. There are vented logs without a standing pilot listed to ANSI Z21.84, which indicates they are match lit only without a standing pilot. These logs are predominatly West of the Miss. River.

As far as problems from leaving the damper open, I have seen on most Ventfree units where down drafts and huge amounts of secondary air into the combustion reaction cool the flames forming CO, aldehydes, soot, etc. While there are "dual listed" logs meaning they are approved both as vented and ventfree, just understand there has never been an in vivo field study of ventfree logs. Never.

Thanks, Bob.

Thanks, all who answered. I had never associated the soot I see on some ceramic logs with down draft. I thought it came from incomplete combustion and/or people just changing the orientation of the logs because they didn't like how they looked.

Thom, soot is caused by incomplete combustion. This can be caused by a number of things. Downdrafts or flow reversals cause the hot gases to squash the flames distrupting the normal mixing of air and fuel. If the flame impinges on a log, the flame is cooled. Stray air currents can cool a flame directly (too much secondary air) or they can distort the flames causing impingement. Regardless, you break up the three T's of combustion: Time, Temp., Turbulence. With the gases cooled and improperly mixed, the result is black stuff.

HTH

Thanks. That said, when one sees incomplete combustion evidence and no obvious causes, like bird's nests or exwife bodies, is that reasone enough to call for a level 2 inspection? I would think so.

Thom, NFPA 211 suggests a Level II on the sale or transfer of property, on the initial inspection or if there is a problem noted.

So, not being from fireplace world, how do you determine there is a problem? Knowledge and experience. We cannot teach over this forum what you need to know. You get that by taking every course you can at conventions, trade shows, nite school, etc. or cutting to the heart of it and take Dale Feb's full course. If you call for a Level II based on seeing traces of soot (BPM), you'll get your butt kicked when it's a vented gas log set that uses ceramic logs---they ALL soot.

Nick

My concern is the age of the unit, when you say its a wood burning unit did you get that from a plate in the unit. If the unit is very old it may not be tested for any gas appliance use, you must ascertain the make and model if at all possible.
Its that plate and information that will give you the next course of action, either you will have enough information for an informed opinion or you will be able to refer on for further evaluation from a qualified source.

Kevin T Stewart
F.I.R.E. Inspector EDC

Originally Posted by Bob Harper

Thom, NFPA 211 suggests a Level II on the sale or transfer of property, on the initial inspection or if there is a problem noted.

So, not being from fireplace world, how do you determine there is a problem? Knowledge and experience. We cannot teach over this forum what you need to know. You get that by taking every course you can at conventions, trade shows, nite school, etc. or cutting to the heart of it and take Dale Feb's full course. If you call for a Level II based on seeing traces of soot (BPM), you'll get your butt kicked when it's a vented gas log set that uses ceramic logs---they ALL soot.

Point taken. That's why I asked the question. I have been getting a lot of crap because I do suggest a level 2 on transfers. No one else does, so I'm trying to develop a comprehensive list of evidence to support that suggestion from NFPA 211 .
Re: Dale's course and all education; I get as much as I can afford in every area I can. I have doubled the required hours of CE each year I've been in business. I do not expect to learn everything I need to know from any one source, much less a blog. In a perfect world, I'd stop inspecting and just go back to school. But, all things being imperfect, I prioritize for my market and license CEU needs. And for this market, education on Stucco and EIFS, HVAC, wind storm construction, and thermal imaging have taken precedence. And though I do love where I live, it is not exactly a hotbed of convenient education. When I go to seminars and schools it is a substantial investment in travel and time in addition to that for the initial cost and time dedicated to the training itself. And, when I checked last, Dale's school wasn't listed with TREC for CEU credit.
So, until I am able to make the investment to travel to Virginia for Dale's course, do you have suggestions for what you would consider to be worthwhile online education courses re fireplace inspections? I can tell you that what has been discussed on this site has been more valuable than the two TREC sanctioned courses I have taken in person.
When I asked the incomplete combustion question, I was not referring to trace elements of soot on ceramic logs.
As always, your responses are appreciated.

Kevin, the sellers had stated they had converted the unit from wood buring to gas. That's what I went on.

And like I said earlier, I am quickly discovering the amount of info I know about fireplaces is nowhere near enough. I need/want to take the F.I.R.E. course.