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Converting a prefab fireplace


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While inspecting a home yesterday I came across a prefab fireplace that had been converted into a wood burning. The glass was gone and all gas and electrical was removed. My main question is the venting. It seems like I have read in the past that the venting requirements for prefabs are different than those for wood burning fireplaces.

Any ideas?

Thanks!

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Fritz,

Me no expurt neither, however...I call it a prefab, maybe it's called by another name as well. Normally it's an enclosed unit with fake logs and a gas line with a on off switch located near the fireplace. They usually will have a glass pane that is not readily removable. You're right, it is a factory built gas appliance. I don't have any photos of this one in particular, but it has definitely been converted into wood burning. My concern is the flue. I'm pretty sure the requirements differ for gas or wood burning.

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I agree, it sounds like a gas appliance if you think a glass panel was removed. They are not intended for wood burning. It may be worth a trip back to get the model and make. Gas appliances usually use the B vent (double wall) requiring 1 inch clearance. wood burning have a larger vent with more clearance, usually 3 inches clearance and often triple wall.

I'm sure a fireplace expert will read and comment, but it doesen't sound safe.

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Rob, if that was originally a gas appliance I'd be way more worried about it burning the house down than how appropriate the venting might be. Converting a gas appliance to woodburning is nuts. The wood fire can get WAY hotter than the appliance is designed for or capable of handling. You're looking at a fire hazard, IMHO.

Brian G.

Send Up the Big Red Flag [:-scared]

www.accuspecllc.com

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Well, nobody likes to claim expert status these days... :-) But, I am a 12 year journeyman mason and am familiar with most types of fireplaces and wood burning stoves. (lived in two 100 year old houses that only had wood heat... even had a copperclad cook stove! You know.. with the high medium and low lids? That sucker had a firebox the size of a shoe box! It went through tons of wood that had to be split very small. I finally converted it to coal! At any rate I used to cut and split about 7 cords a year for me and tons more for sale to others during the winter when masonry was slow... definitely warms the man twice!)

If it had functional glass doors, it was most likely designed for wood in the beginning and was converted to gas logs and returned to wood.

If it has a damper and an 8 - 10" diameter flue, it's a pretty sure bet that it was originally designed for wood.

A far bigger concern is when people take a metal pre-fab fireplace designed for wood-burning and install ventless gas logs and seal that damper closed.... Now THAT can burn the house down! Manufacturers of such fireplaces are pretty nervous about this unintended use!

As someone previously said, a gas log fireplace unit will have a much smaller diameter "B"-vent flue and will most likely not have a damper. I don't believe I've ever seen working glass doors on a factory build gas log fireplace? They usually have a fixed pane if they have one at all.

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The flue was between 8 and 10" and a damper was present.

These prefab gas log fireplaces are pretty common here. They all look quite a bit the same. Top and bottom grill, bottom pulls open to access the gas valve and electrical and blower. And they all have a stationary glass pane. This one had the glass removed. Someone had installed tile around the fireplace and covered up 1/2" on either side making it impossible to open the bottom grill. Shining a flashlight in there was no gas piping or electrical.

I don't think I will be able to get back into the home.

My gut tells me that I should recommend a licensed chimney inspector, but I hate to pass the buck. Better than burning the place down however.

Thanks for your insight!

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Around here I see lots of factory built wood burning fireplaces that have had ceramic gas log sets installed in them. With the gas logs, the damper should be blocked open. What you're describing sounds to me like someone but a gas log set in a wood burning factory built fireplace, then decided to take it out, but didn't remove the gas log set guts.

If you're unsure, you can always recommend an NFPA 211, Level II inspection for any solid fuel burning fireplace. NFPA recommends the Level II inspection any time a house is sold and the recommendation is part of my boilerplate.

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Hi,

If there's a flue that large with a damper it was designed for wood and is probably okay for gas. There are a lot of them here designed specifically for either. These have a little depression at the bottom back corner where a knockout is removed to run the gas pipe in for a log lighter or gas log set. Outwardly they look nearly identical to a gas fireplace but they're designed to be used either way. The bottom panel on those usually doesn't open and is fixed.

It's a zero-cleance fireplace - not a pre-fab. Pre-fabricated fireplaces are entirely different animals cast in a factory off-site, brought in by truck and then lifted into place with a crane. The Seattle Home Show opened yesterday. Take a trip down there today if you've got time and talk to a couple dozen installers. I always learn so much down there that I think the organizations should give MRC or CEU credit for attendance.

Personally, I wouldn't be concerned about a home burning down because of a ventless log set placed in a zero-clearance fireplace. The refractory walls in these are designed to withstand a lot of heat. I bet 99% of the folks who buy those press-logs at grocery stores never bother to read the instructions that tell them not to burn more than one at a time. I've found zero-clearance fireplaces with the fireboxes so badly warped from heat that they were pretty danged ugly to look at, yet they've held up.

If they can sustain that kind of heat and stay together without burning down a house, I doubt that a little catalytic logset is going to do it. I'd be more concerned with the moisture and particulate matter that will be generated by the device and end up causing all sorts of ghosting and moisture-induced conditions in the home.

ONE TEAM - ONE FIGHT!!!

Mike

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Heard wood-burning fireplaces had been outlawed in new construction here (At least in this county) due to forest fire concerns (Tons of new developments going up in heavily treed suburbs). Randy, have you heard anything about that?

No. Haven't heard a thing about that. Maybe I ought to check into it.

Anyway, the way traditional masonry wood-burning fireplaces are built here is so inefficient. Nobody uses 'em. All the heat goes right out through the flue. They just end up being decorations or a resting spot for a candle set or other ornamentation inside the firebox.

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Huh?

Nobody uses them? You and I must be on different planets. I see some type of gas or wood burning fireplace or stove in about 75 - 80% of the homes that I do and I'd say at least 75% of them are in use.

I went back to edit that post that you've quoted and deleted it by accident (Haven't had my second cuppa yet.)so I posted something different.

Where's that dimensional portal. I want to get over to that side?

OT - OF!!!

M.

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Originally posted by hausdok

Huh?

Nobody uses them? You and I must be on different planets. I see some type of gas or wood burning fireplace or stove in about 75 - 80% of the homes that I do and I'd say at least 75% of them are in use.

I was referring to the traditional, masonry, wood-burning fireplaces. No, I agree, wood burning stoves, inserts, zero-clearance gas fireplaces, pellet stoves etc. are all heavily used around here, in my opinion because they're much easier to operate and they actually can provide heat.

Stocking lots 'o firewood, starting a fire properly and keeping it going in a traditional fireplace is a lot of work when most of the heat goes right up the chimney. Been in plenty of 20+ year homes where the masonry fireplace does not have one ounce of soot or evidence of a fire, especially the higher end homes. Fireplaces are just a decoration.

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Well,

We'll have to disagree there. Sure, I see them used as planters all the time but the majority of the ones that I've seen are still in use. True, they just rob heat from a home but people still like 'em and still use 'em -most of the time in my experience, that is.

Now, where the hell is that portal? Over there in the Saint whatever place or under Plywood Supply? Oh, I know. It's gotta be over there in Stupid Prices because that guy's definitely from another dimension if he thinks any of that stuff is bargain priced.

OT - OF!!!

M.

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Actually, the concern with ventless gas logs in a woodburning metal pre-fab fireplace isn't relative to the ventless gas logs at all. No problem there. It has nothing to do with the fireox materials either. No problem there either. IT has to do with excessive temperatures in the damper/throat area when the damper is sealed shut. Apparently, the metal gets too hot as in red hot.

Zero clearance woodburning fireplaces are designed around and relying on the damper being open and the heat moving smoothly up the flue which pretty much regulates and limits the upper temp.

This information came from certified sweep and author, Jim Brewer who travels as a speaker and has written numerous books within the sweep industry. He cautions that closing the damper in a wood burning metal pre-fab fireplace because ventless gas logs have been installed is a VERY bad idea and that the manufacturers of those units are concerned with this new and unintended use. He points out that the design for ventless gas log fireplaces is quite different and the cost of them is considerably higher all to meet the increased temperatures experienced at the top of the unit. He cautions that the metal in the top of these units can become red hot!

It all makes perfect sense to me. I have a pretty good understanding of fireplace design and actually worked with Dr. Jess Brown in pyrotechnics at Auburn University in TX with some new fireplace flue designs. I built very unusual chimneys to his specs which never needed cleaning.

But, for those who doubt this concern with the ventless gas logs with a closed damper please contact him jbrewer@magic-sweep.com He is the past, director, pres and vp of the national chimney sweeps guild. He is also a master instructor for the Chimney Safety Institute of America.

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I believe I am negligent in my reporting if I don’t list the Mfg., model #, flue type, and associated safety equipment/apparatuses. I see too many pre-fab units improperly installed and with market turn over very few instruction manuals ever get passed on to the new owners.

Improper installation, improper usage, equals disaster.

Also, any units that are modified, unless performed by a fireplace specialist, for whatever reason will no longer meet the standards they were constructed to and therefore are defective equipment and should not be used until they are properly repaired or terminated.

This was in a new home last year. Luckily the fireplace had never been used by the original owners. How many defects can you see?

Download Attachment: icon_photo.gif mvc-014fdisplaced flue.jpg

56.15 KB

http://www.csia.org/homeowners/fireplce.htm

http://fireplaceinspections.com/media/pre-cast.pdf

http://fireplaceinspections.com/media/s ... rounds.pdf

http://fireplaceinspections.com/media/f ... e_test.pdfid="Verdana">

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Aw com'n Randy,

You mean to tell me you've never done any inter-dimensional travel? Man, I feel duped. I was sure you had, 'cuz it sounded like you and I were working in parellel dimensions. I just wanted to find the portal into yours so that I could come visit and I figured you knew where the portal was.

Nuts! Now I'm never going to meet my other self. [:-hypnoti

OT - OF!!!

M.

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