Masonry Chimney repair vs. vented vs. ventless gas log
Hi All,
We have been advised our wood burning fireplace / chimney is unsafe to use. We've been in our home almost 2 years and were advised this on the home inspection and thus have not used it since we've lived here.
We're now in the process of wanting to convert the fireplace to gas and install a gas log set. Note: we don't want an insert as our main objective is not really heat. We're looking to use the fireplace only occasionally, and the goal is ambiance. It will not ever see a daily or heavy use case where we are using it for primary heat (even in a power outage my generator will run the boiler).
Inspection/estimate details: There are 4 interfaces where the clay flue tiles meet; 3 of the 4 look "pretty darn good" from the inspector. The 4th one (middle chimney area) is missing some mortar at the joint. The tiles themselves are not cracked. The chimney is in "fair" condition as far as cleanliness - only minimal creosote build up that would be taken care of by their most basic sweeping service offering. There are some minor cracks in the firebox that need tuck pointing. The very top of the chimney needs the concrete to be redone for proper pitch as it's lacking enough to prevent water build up. The structure of the chimney is great. The company is calling for a "heat shield" as the recommended repair, which works by applying a coat of mortar to the inside of the chimney using a pulley system of some sort to fill all the cracks (really, just 1 crack as far as I can see it). That plus the sweep, and the concrete and tuckpointing → $$$$.
Gas logs: we have been looking at vented and vent free systems. As I understand it, we could put a vent free gas log in the firebox, close the damper, and be done with it. BUT - depending on where you look of course - vent free gas logs will kill your whole family instantly. Also as I understand it, a traditional vented gas log set will require the chimney repair as noted above.
I have also thought - after a sweep and the mortar repairs on the firebox - would it be possible to run a vent free gas log and just crack the damper open a tad to let out some of the moisture/fumes (if any) and still be safe? With a clean chimney and very little heat escaping…is the ONE joint that's missing mortar going to burn our house down? I find it hard to believe but I don't know.
What's our best course of action here? If money was no object sure (presuming it's not a scam) we could do the heat shield and be good. But is that worth it for our (infrequent) use case? I'm not sure.
New to the forum and would appreciate advice!
Comments
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home inspectors should only advise call a Qualified licensed and insured contractor.
get it properly inspected. Then make a decision.But do NOT go ventless
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Thanks for the reply! The home inspection was a couple of years ago.
The inspection today was from a chimney repair company, so I'm wondering how objective it is.
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Did they explain in clear language what if anything was wrong?
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Yeah…I described it in my initial post exactly what they said! lol
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Gas fireplace with a stainless-steel liner in the chimney.
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The only option I'd consider.
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
Thanks for the replies guys.
OK - forgive my ignorance. Gas fireplace with a ss liner…can a SS liner be used with a gas log? Or are we talking about an insert?
We weren't really looking for inserts becuase:
- Not needed primarily for heat (just ambiance)
- Running electrical to that location for the blower would be a big tear up (whereas gas line is easy). Do inserts all have blowers…?
- We aren't thrilled about having the fire behind a closed door. Can these run with the door open…?
Would greatly appreciate some more insight.
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I'm not talking an insert — I'm thinking a gas log set in the existing fireplace with a SS liner up the chimney. Something like
Br. Jamie, osb
Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England0 -
OK - but this is where I don't understand (and again sorry I'm trying to learn about this stuff haha)…with the liner…what does it connect to? Right now we have a traditional damper / wood burning fireplace. So there isn't like, a circular outlet at the top of the fire box that would connect to the SS liner and run up and out. Would we have to box off the top of the fireplace with like a big metal plate with the opening designed to connect to the liner? How does this work?
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You can get gas there but not electric?
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Yes. It's on a slab; gas line will come from outside right through. 8 ft run. Electric would be much more difficult…I'd have to cut up drywall and tie into the family room outlet circuit. Yuck.
From some googling…it seems like I need a direct vent gas FIREPLACE, not an insert:
I'm not sure why it took me so long to find this…but something like this is exactly what we need. Inlet air is from the room, front is open like we want, but mechanically it connects to a liner from the top since it comes in its own firebox. Hole is right there and would connect to a tube dropped down the chimney…
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The chimney must be suitable for the class of service. The repair systems recommended are very popular but do not meet the standard and thus not a recognized repair. To relined a fireplace you would need to shatter the flue tiles removing them completely then installing a very large ss liner sized to the opening of the fireplace plus room for the requisite insulation to meet a 2,100F rating. Gas logs are not a repair. Cracking the damper on VF makes them vented. Vented logs require the damper wide open. You can get logs that are 'dual listed'- VF and vented but you must pick which way you're going to run them and stick with it. Cracking a damper causes flame cooling and impingement resulting in CO and soot.
I'm rather puzzled why you decline a gas insert then state the best solution would be a gas direct vent. If you're talking about putting this gas fireplace into your existing one you want an insert- not a direct vent built-in model, such as the one referenced. BTW, it does not use room air for combustion-its direct vent. The unit shown is an entry level model.You can ignore the advice from the inspection regarding the missing mortar and open joints but there are plenty of reasons they need to be tight. In fact, they're so important we put them into the code. Open joints not only allow 'bad stuff' to leak into a home or moisture/ air into the flue. It kills draft pressure and causes flow disturbance.
We call VF logs 'lung vented'- you're the chimney. No, they won't kill you instantly. Really? Do you think these logs would be allowed in homes? There would be thousands of bodies pulled out very morning. They do emit 200ppm CO even when running properly. They stink. They make other nasty, unhealthy compounds like paraldehyde, acetaldehyde, and NOx. Did I say they stink?
Vented logs must be listed to ANSI Z21.60 or Z21.84. Not all logs are.
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Thank you for the detailed reply.
To clarify - the heat shield method where they re-mortar the inside of the chimney is not recognized as a quality and appropriate repair? Or is that a safe choice? According to the company, it has a lifetime warranty and we can burn wood or convert to gas no problem as the chimney will be perfectly safe to burn anything.
Long term thinking…maybe going this route is best so we can be safe to use whatever we want in the fireplace (either wood if we decide that, or a properly vented gas log). Assuming this repair method is appropriate and not a scam of some kind.
Regarding an insert…I guess it just wasn't our first choice because we don't really want the closed front as it doesn't really give a good ambiance which is what we're after (as opposed to heat being the primary goal). If this is the only good safe option then maybe we just go this route I guess…it just wasn't what we were picturing in the space that's all.
Thanks again for the details. I know some of my thoughts might be puzzling, but I'm new to this stuff and trying to learn!
PS - about the VF "killing you instantly" - I was joking lol. Just playing off the fact that if you try to research it, half the people say it's perfectly safe and half the people say it's a really big hazard. Maybe the only ones saying it's safe are the ones selling them. I don't know.
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companies can Claim anything they want. It’s the local Authority having Jurisdiction that determines yes or no.
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Sorry @Bob Harper , but it's obvious that you didn't bother to watch the video.
This patented and certified system makes stainless steel liners obsolete.
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and I’m not going to accept anything the manufacture claimes.
3200 degs in the fire, what’s the stack temp after being deluged by 70* air and a lot of it!0 -
I watched.
not buying it!1 -
Well Mike, I DID watch the video. In fact, I have installed Guardian cast in place liners listed to UL 1777. The company I used to work for did a lot of HeatShield against my advice. When they took the F.I.R.E. course they learned what I said. The product you espouse is making misleading statements. They claim it is 'certified'. To what standard? If a product is tested to a nationally recognized standard and found to pass, that owner will proudly market their product as being listed by a recognized testing lab to that std. and state what the std. is. I found some vague references about this product as having once been listed to UL 2425. That is a defunct listing standard. Therefore, anyone claiming to be listed to is (as HeatShield also does) are being dishonest and misleading. It is not a valid listing anymore.
One of the problems with resurfacing is it does not correct the problems of terra cotta liners, which are many. Another major problem is that it does not require the removal of fugitive creosote from the interstitial spaces within the chimney where it has leaked out. You can resurface all you want but you may still have a lot of highly volatile fuel captured within the chimney where you cannot see it or remove it without removing the flue tiles. The product reduces but does not eliminate thermal shock. The product does not provide a zero clearance to combustibles the way a UL 1777 liner listing can so, no, it does not come close to replacing or obsoleting ss liners. If you have combustibles encroaching upon a chimney with that product, the house is still in danger of ignition should a chimney fire occur. The liner listing, UL 1777 tests with 3/4" plywood painted flat black, edges taped with a thermocouple every 6" grid in direct contact with a single wythe brick chimney. A gas generator is inserted at the base of the 10ft chimney and fired to 1,000F x 8hrs. If any single thermocouple located at the ground intersections rises more than 95F above ambient, it fails. If it passes that, the temp. is increased to 1,400F x 1hr. If it passes that, it is allowed to cool to ambient then blasted 2,100F x 10 minutes. That test is repeated for a total of 3x. The liner is inspected for damage, separation, or intergranular corrosion. A typical chimney treated with a joint repair cannot come close to passing this test. Since every masonry chimney in America has combustibles touching, they require a liner listed at a zero clearance for 2,100F.
Guitardood: I would advise you to find another word other than 'safe'. There is NOTHING safe about bringing fire into a home. Safe is an absolute state that is unobtainable. We can, however, make things saf-er by using products listed to a recognized national standard and having been investigated by a recognized test lab and passed. Claiming a product has undergone many tests does not prove it passed nor does it reveal what the test std. was.
I'm cautious here with some language because many people read these posts without revealing themselves but use information here as the basis for decisions on how they should proceed, what to worry about or not and what products, techniques, processes, etc. are relevant to their concern or how/ if they apply.
BTW Mike, I sit on the UL Standards Technical Panels and the NFPA 211 cmte. so I'm kinda' familiar with this stuff.
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Thank you Bob, I stand corrected.
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Thanks Bob for the detailed reply. I appreciate your time!
So to clarify, the best choice here is pretty much hands down a gas insert then?
I'm gathering based on everything above that this is a good option with little or no downside?
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with approved SS liner.
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right…this would be something that has 2 SS tubes running up, one for inlet and 1 for exhaust, right? From my research that looks like how these inserts are designed.
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Doubt you will have room to run 2 SS liners in same plenum. In old house typically just pull air from house.
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Ahh…I see. Got it. This would be through some sort of vent on the front panel then I take it…hopefully not a "pump" of any sort to pull the air?
Hoping to find something that doesn't require electricity to use.
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You need an insulated ss liner for a wood stove insert. A pellet insert requires a ss liner that does not have to be insulated just like oil or gas CAT I liners.
A gas direct vent insert requires 2 liners- one for the combustion air and the other for the exhaust to a special termination cap. Most of the industry uses two 3" aluminum flex liners. You will see an occasional 4" intake or exhaust or 4&4 but mostly 3&3. A few units, such as some old Heat N Glo's came with a 3ft ss starter due to how much heat went up the stack. This starter mated to a standard aluminum flex liner just above the damper in the smoke chamber.
Getting two 3" flex liners down a nominal 9"x13" OD flue tile can be problematic, especially where the flue offsets or the tiles were not properly stacked one upon the other.
Regardless, pick a unit then refer to the listed instructions for the approved venting.
Bob
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Not hijacking a thread but want to offer a warning:
The house I grew up in(preteens to graduation) caught fire due to a chimney fire. We were not the owners anymore when it burned, we had long since moved. House was a total loss and torn down. Wood insert installed into an old chimney was the cause. Possibly the same one that was there when we moved. The house burnt mid December a few years back, current family lost everything only weeks before Christmas. Luckily no one was home when it started. The husband is/was on the volunteer fire dept for the twp/village.
It can happen to anyone.
First picture is one I took with our first digital camera circa: 2003
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