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unvented gas log fireplace


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Aside from all the other undesirable aspects of these things, I saw one today that doesn't have a hearth extension in front of it.

I've been searching around, but can't find anything that says there has to be a hearth extension for these things. Do they need one since they don't burn wood & wouldn't have cinders rolling out onto the floor?

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I looked a few years ago and could never find a requirement.

From Heat & Glo:

Hearth Extensions

A hearth extension may be desirable for aesthetic

reasons. However, ANSI or CAN/CGA testing

standards do not require hearth extensions for gas

fireplace appliances.

"Sometimes I've believed as many as six impossible things before breakfast."

Lewis Carroll

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According to Dale Feb, the main purpose of a hearth extension is to protect combustible materials in front of the fireplace from radiant heat; such heat can lower the kindling temperature of the combustible material (pyrolysis), posing a fire hazard. Again, according to Dale, hearth extensions are mainly for this purpose, not as commonly thought to protect against logs rolling out of or embers popping out of the firebox.

I've been flagging the lack of a hearth extension for gas logs 'cause of this.

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Originally posted by hausdok

I don't write them for lack of a hearth extension. They aren't any different than a gas oven in my book. There isn't any hearth or fireproof material required under gas ovens, so why would we need one under these?

OT - OF!!!

M.

They are different from an oven. The flames in a gas oven are protected under the drip/burner pan, and they don't emit much of any, if any at all, radiant heat out of the oven. At least I thunks so.

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Well,

I've inspected a bunch of gas fireplaces and stoves, Jerry, and I can safely put my hand under all of them and feel very little heat. In fact, I can't even begin to count the number of times I've opened up the underside of gas fireplaces and found the manuals lying under them - some of them being many years old, and there's no sign that the paper was overheated.

Dale Feb is a really smart fellow and I respect his experience, but my own tells me that pushing a hearth in front/under gas fireplaces and stoves is kind of over-stating the issue.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by hausdok

Well,

I've inspected a bunch of gas fireplaces and stoves, Jerry, and I can safely put my hand under all of them and feel very little heat. In fact, I can't even begin to count the number of times I've opened up the underside of gas fireplaces and found the manuals lying under them - some of them being many years old, and there's no sign that the paper was overheated.

Dale Feb is a really smart fellow and I respect his experience, but my own tells me that pushing a hearth in front/under gas fireplaces and stoves is kind of over-stating the issue.

ONE TEAM - ONE FIGHT!!!

The radiant heat can't reach the manuals under the fireplace, just as the radiant heat from a gas oven flame can't get beyond the drip/burner pan. Think "radiation". Radiant energy travels in straight lines from the source of heat (the flames, in these instances), and is absorbed by any surface it encounters. It's this radiant heat that poses the problem.
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Exactly!

That's what I'm talking about! I don't see the radiant heat striking the floor immediately in front of these things either! That's why I say it's over-stated.

I just don't see it happening. It might be fine in theory but I haven't found it to be the case when these things are being used. I dunno about Illinois, but out here practically every home has at least one fireplace and in the new homes they're all gas now. Today's home had three gas fireplaces in it. Those free standing gas stoves have more air moving underneath them than the fireplaces and they're all equipped wih refractory panels that direct most of the heat out through the front so there's relatively little heat behind them, under them or off to the side of them compared to in front of them and the area where you'd want to put a hearth - that 18 inches - it just doesn't get too hot.

I routinely have people sit right in front of these things while I'm working and they're fine. They just don't produce the kind of heat that you're envisioning - at least that's been my experience. I've said my piece about it. If you aren't convinced,you aren't convinced. Just don't expect me to every buy off on the idea that I need to recommend floor hearths in front of these things when they'd got a zero clearance requirement.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by kurt

Yeah, sounds like a stretch to me.

I'll stick with Dale (who I truly respect), and his explanation of the long-term effect of small amounts of heat oxidizing the combustibles, lowering their kindling temperatures. I believe your thoughts are kinda like looking at a furnace B-vent touching a wood roof deck in an attic and saying it's not a problem since there's no fire.

Chris...just what, exactly, does heat-affected carpet or wood floor look like? Thanks.

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Now, now, Jerry. Calm down. I didn't say I didn't respect Dale; clearly, the guys a mensch. I said it was a stretch.

Since the mfg's. say it's OK, the codes say it's OK, then Dale is standing out there all by hizzelf and I don't think he's got any data to back up his claims, no? If he wants to promote unique & unscientific/unvalidated opinions, that's fine w/me; I do it all the time, although mine tend to do w/fuzzy ideas about space/time warps and benevolent chunks of hyper-intelligent silica streaming through space colonizing planets, not burning LR floors. (Wear your aluminum beanie, or the silica can read your thoughts everyone.)

Since we all live in a world where we like the idea that our comments will hold up in court, Mr. Feb's position is tenuous @ best, and most likely unsupportable outside of his personal opinion. If he comes up w/actual data that says it is dangerous, then I'll shut up.

And, I didn't say the B vent in contact w/combustibles was OK. I said I've never found one that got more than hand touch warm.

Do you have the little purple cloth sack out out of it's hiding place again? [:-angel]

(Don't worry; Jerry and I are antagonistic friends; this is not an argument; it's me logically leading Jerry to the realization that he's a dumbshit.)

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Chris...just what, exactly, does heat-affected carpet or wood floor look like? Thanks.

Kind of like porn- I know it when I see it.

FWIW, I went over to my neighbor's house and turned on his gas fireplace. Considering it was 111 degrees yesterday, he was extremely accomodating. I let it run for 45 minutes. The wood laminate flooring that butts the unit reached 86 degrees.

Then I went over to the wood shutters on the west facing windows. They were 116 degrees. Using your logic, I will now need to write up any wood that gets direct sunlight as a pyrolytic condition: Prolonged exposure (about 8 hrs a day, about 50 days a year) to radiant heat.

I will also need to write up all of the roof trusses and sheathing, as they reach temps of more than 145 during the same period. But (me thinks) that would be conduction and not radiation.

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Originally posted by Jerry Simon

...just what, exactly, does heat-affected carpet or wood floor look like?

I think that would be a good question to ask Mr. Feb, since it's his theory that they are indeed affected. If he has an answer I would be genuinely interested in hearing it. Lots of those babys here too.

Brian G.

Seeing Is Believing [:-magnify

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When I took Dale's class, I was very surprised that, according to Dale, anyway, the main purpose of a hearth extension is the protection of combustibles from radiant heat. I always though it was for embers or logs, as Kurt mentioned.

Perhaps he is wrong, and all your field experience *not seeing* problems is more definitive. Uh, I think I'll stick with Dale versus you all not seeing problems. By the way, Dale told dozens of war stories about fireplace-related house fires. Some were radiant-heat related. Truly amazing, this fire-safety voodoo he preaches.

Kurt, I didn't mean you with the truly-respect part...that was for Mike, who on one hand says he respects Dale, but then takes a 180 position from Dale. Again, just 'cause Mike ain't seen a problem doesn't negate Dale's teaching, in my mind anyway. Has anyone else taken Dale's course? Dale is an expert's expert. I'll stick with him 'till proven otherwise, and not just proven by "ain't seen a problem".

Now, I will admit, it was an early morning class, and this all could have been a dream sequence.

Dumbshit (Graduated from the purple sack up to Bookers)

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I just walked in; I figured you'd be roasting me by now....

We all know Dale's an expert's expert; the guy knows what he's talking about.

In this one single specific thing, I think he's wrong. He has nothing to back up his opinion, other than personal observations, which you're telling us are not worth considering. How are his personal observations accurate, and ours are not?

Chris' little "test" has a lot of common sense application. I did the same thing this morning @ an inspection; I turned on the POS fireplace in the cheesey little condo I was looking @, and left it on the whole inspection; when I measured the floor temp, it was the same as the room air temp.

This is how folklore gets started. I do it, you do it, everyone does it, including Dale in this case. At this point in the career path, I want to go the other way, and start eliminating folklore; I've caused enough confusion w/ill formed opines, and I gotta work overtime to rebalance my karmic debt to the profession.

Mr. Feb's gotta come up w/something better than war stories on this particular item. If he says it starts fires through pyrolization, he's gotta come up w/data that demonstrates it. If & when he does, I retract it all and start campaigning for hearth extensions in front of POS gas fireplaces.

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Originally posted by kurt

How are his personal observations accurate, and ours are not?

Uhm, he investigates fires for a living, and teaches fire-safety courses for a living. Just my opinion, but I think his observations/opinions might hold more weight than ours. A shitload more.

That being said, your observations may certainly be correct.

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Originally posted by Jerry Simon

...who on one hand says he respects Dale, but then takes a 180 position from Dale.

Come now Jerry. If that's a sign of disrespect there's virtually no one on this board who respects anyone else here. I've personally taken an opposite position from every single person I do respect around this joint, at one time or another.

I also respect Dale, but given that the manufacturers, building codes, and lots of practical not-seeing-a-problem are the conventional wisdom in this debate, the burden of proof is clearly on him. He may be right....but can he prove it?

Brian G.

My Wife Is Radiant, But She Don't Need a Hearth [-crzwom]

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We have a "not to be named" expert up this way. Former ASHI President, long time inspection school owner, and 20+ years in the business.

He swears that air moves through flex ducting at nearly the speed of sound, and I don't believe that crap either, based on my own "observations and experience"- but then again I don't drink Kool-aid, unless I mix it myself.

BTW-I've also been involved in fire investigations. We had one where the much ballyhooed instructor/local expert swore the bedroom blaze started when a vitamin bottle on the window sill acted as a magnifying glass and started a newspaper on fire, in an open armoir. Everyone bought that until the kid that lived there set the house on fire again and confessed to the first one.

Like home inspectors, you give me five fire investigators and at least one will have a different opinion. I'm not disparaging your "expert" Jerry, any more than you're disparaging me.

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This is interesting, because none of what we do is magic. It's just a lot of stuff, more stuff than any one person can figure out on their own. We need folks like Dale to focus & collect information in a specific discipline so the rest of us can be informed.

That said, imagining Dale has magic observational powers that are beyond what any one of us can divine is pretty silly.

I, or anyone in here, can look @ a gas fireplace without a hearth extension & figure out what's going on. So, I don't personally place any particular stock in Dales opine on this very specific item, unless he has data to back it up.

I imagine the fireplace mfg's., UL, the NFPA, the CPSC, and anyone else involved in this sort of analysis do have data to support their contention that the hearth extension isn't necessary. Maybe my imaginings are just that; imaginings, but I tend to think not in this case.

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Originally posted by kurt

I imagine the fireplace mfg's., UL, the NFPA, the CPSC, and anyone else involved in this sort of analysis do have data to support their contention that the hearth extension isn't necessary. Maybe my imaginings are just that; imaginings, but I tend to think not in this case.

Kurt...Right or wrong, I think I've flagged this as a problem twice, maybe three times ever. And, I'm guessing you asked the initial question in this post because it's the first time or so you've ever seen a *missing* hearth extension.

This may be a stretch, but since I've hardly ever seen missing hearth extensions, why do they bother to ever put one in at all? Aesthetics only, as one mentioned? Or perhaps a real radiant heat problem? I really don't know, I guess. I know people have posted here that they often don't see extensions, but I don't, and again, I'm guessing you (Kurt) haven't either, thus your question.

Apology to Mike & Chris for any slight...my daughters aren't home this week...I have to be a jerk to someone.

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You know, I think this might have been the first one I've ever seen without an extension. It just looked wrong, hence, the original question.

This is another good reason for me to hate those stupid gas unvented fireplaces; they confuse things.

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No worries Jerry, I don't take this stuff personal, and I have two girls of my own. If you're interested, I'd be willing to sub-contract them until yours are back!

One question regarding the hearth and Dale's assertion that they're installed primarily for radiant heat and secondarily for embers/ashes (maybe you can ask Dale): When was this theory established?

My reason for asking is that I've seen drawings of hearths in pictures dating back hundreds of years. I wouldn't think that the pilgrims (or whomever) would have any idea what pyrolysis was.

Not being a smartass, just one of those questions that rattle around in my head.

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