Is it safe to put an insert in a Zero Clearance or not?

[SimplifySC]

New to the forum. Thanks for all of the folks who post that make this such a good resource.

Here is my situation... Built a new house 2 years ago here in the upstate of SC. Shame on me... Have had several wood stoves in the past, but the wife wanted the look of an open fire in our great room so we installed a Majestic 50 Inch PreFab fireplace with a 12 inch Double Wall Class A Flue that goes up about 30-35 feet through a chase. The great room has a vaulted ceiling that opens to the 2nd floor and is probably 24ish feet at the peak. Fast forward to today... We have discovered that even with fairly mild winters here in SC, it is drafty in our house and our heat runs nearly all the time trying to keep the house at 65 degrees and our open fireplace - even with a Mr. Radiator blower, isn't helping much. It is one thing to be cold much of the time... It is another to spend $350 per month just for the "privilege" of being "a little cold".

My plan was to go back to my roots and install a wood insert into the prefab fireplace. I called my local sweep out yesterday and he looks at my setup and recommends I buy an insert and we place it in the existing Pre-fab, make sure the existing damper stays open (or remove it), surround/insulate off the rest of the open firebox and let the smoke from the insert just go up the existing 12 inch liner. Sounded like a good plan to me and I have been looking at units like the Jotul 550 that say they can be installed in a PreFab fireplace.

As I am researching to finalize the decision about what stove to buy, I have come across all sorts of conflicting information about the viability of this setup. The Stove manufacturers say you can install in a PreFab Fireplace, but Majestic says in their website not to do it. The sweep says it will work just fine, but other experts online say it is a chimney fire waiting to happen.

I have no idea what to do now? I am getting two pieces of advice that says the exact opposite things. Any thoughts? Hopefully some of you have traveled this road and have some words of wisdom. Thanks in advance for your help.

Chip

 

[mellow]

Get an insert rated for a ZC fireplace, the golden way to to do it is to have both manufacturers give the blessing but that rarely happens. You will want to run a 6" liner inside your existing liner, insulated would be a bonus. The 550 is a nice insert if you can fit it in there.

PS: I would find a new installer.

 

[bholler]

the official ruling from csia is no unless both units are rated for it. and to my knowledge there are none that are. I believe there is an insert rated to go in a zc cant remember which one at the moment I will look it up but to my knowledge there is no zero clearance that is rated for an insert. and it absolutely is not safe to just install it sort of like a slammer and use the existing vent. I am sure it could probably be done safely but no reputable professional should do it simply because of the liability. if you do it you need to make sure that all of the existing insulation and air passages in the zc unit are there and functioning properly.

 

[Charles1981]

Yep, your sweep's idea about directly venting into the current 12 inch liner is not a good idea because of draft and creosote formation.

As far as inserts go..if that is a problem....can he run a free standing stove with a rear exit up the liner? Is that kosher?

 

[bholler]

according to code no it is not ok. I se no reason it wouldn't work but unless the zc was ul listed for that it is not allowed. and if there ever was a problem your insurance probably would not be ok with it either

 

[SimplifySC]

I will scrap the insert idea. Trying to come up with other options short of ripping out all the rock work and everything to get the Pre-fab out. Any reason why this wouldn't work? I have a 20 inch rock hearth in front of the Pre-Fab. What if I bought a shallower free-standing unit like an F500 or 600 that is only 16 inches deep or another stove that had a rear vent option and then ran the flue into the firebox opening and made a 90 degree connection and met my existing chimney where I add a 6 inch stainless liner? I could then cover the open firebox for looks purposes but still get in there to break the 90 degree elbow for cleaning. Any reason that wouldn't work?

 

[bholler]

well legally no you cant add anything to a ul listed unit that was not specified in the ul testing. that means no stove insert or liner can be run through your system and meet code. unless your unit was tested for it but I am all but positive it wasn't. like I have said before that doesn't mean it cat be done but it does mean that it should never pass any type of inspection. and if you do it yo need to make sure that all of the air passages in the zc unit it self and the vent system are still fully functional because without them heat will transfer through.

 

[Heatsource]

nevermind

Majestic Tech customer service: 800-867-0454
give them a ring to confirm install of an insert into their zc fireboxes

 

[SuperGenius]

Most of the Travis flush inserts claim to be usable in ZC fireplaces, as does the Napoleon EPI3 (those just happen to be the ones I'm looking at lately), although there might be some stipulations about meeting UL standards, etc. You'd think any wood-burning ZC FP could handle a sealed wood stove surrounded by its own sheet metal box. It just seems safer than an uncontrolled open fire, but maybe I'm missing something.

 

[begreen]

Inserts are a stove within a convective envelope. They are never going to reach near the potential temperature of a large, open fire in the ZC fireplace. If the insert mfg. approves the insert for ZC install and it fits without compromise, I am ok with this install.

 

[wkpoor]

This has come up prolly a hundred or more times on here and will continue because so many houses have ZCFs installed. Somewhere way back somebody raised the concern about installing a heavy insert into what amounts to a sheetmetal box who's floor may not support it.

 

[begreen]

It's fairly easy to support the body of the insert with layers of cement board, bricks etc.

 

[BrotherBart]

Somewhere way back somebody raised the concern about installing a heavy insert into what amounts to a sheetmetal box who's floor may not support it.

That was me. People talking about shoving an insert into a ZC scares the hell out of me. The whole thing was made and installed on the cheap in the first place. The reason I wouldn't let the builder install one in the first house I had built. In 1977.

 

[wkpoor]

I think there is nothing wrong with a ZC as long as its used for what it was designed for. An occasional open fire.
I would guess shoring up the bottom would require removal in most situations. At that point it would be easier to just do it all over.
Also I read on here ( I was paying attention Bart) that ZCs have a nasty habit of rusting out where the pipe meets the collar on top of the box. So unless someone is trying to save money on an nearly new ZC install it prolly makes no sense to not just rip it out.

 

[stoveguy2esw]

first off, it has to be a ZC rated insert, secondly the structure has to support the weight thirdly most ZC's are connected to a UL 103(non HT) 1700F air cooled flue system which is death to draft for an EPA insert , so a reline MUST be done , on an exterior flue it likely should be an insulated liner.

lots to research/do before you strike you're first match

 

[SimplifySC]

Wanted to follow-up back up as so many of you were gracious enough to reply. Over the last several weeks I have been talking to local Stove dealers, my insurance company, and a CSIA sweep who came out to look at my setup. State Farm said as long as my installation passes codes, they will cover me without any additional premiums. As I have researched more, my particular fireplace in the manual says "No Insert" so I have ruled that option out. My sweep told me an alternative he would approve and install is a Hearthmount Freestanding unit like a 400 Castine if Jotul AND Majestic approved it. I called Jotul and they were very helpful. The Tech sent me a nicely documented Jotul spec sheet on how to install a number of their specific freestanding units in front of a ZC. He said as long as my unit is a UL or Omni certified fireplace, Jotul would support it and there was no point in contacting Majestic. I will try Majestic tomorrow, but I am not hopeful. Why would Majestic say yes and accept any liability for something when they are not making an additional sale and have no incentive to approve this. We will see what they say. Frustrating thing is I don't think the issue is whether it will work or be safe. I think it is purely about liability and Covering Your Backside. If Majestic says no, I may contact my local codes folks to get their take. I am guessing they will approve it if I do it by the specific instructions Jotul lays out even if Majestic doesn't want to bless it. Thoughts? Thanks everyone. I type this from an icy South Carolina in the midst of a big snow/ice storm wondering if we will have power for the night - just the reason I wanted to make this transition back to a stove. Pretty frustrated......

 

[bholler]

That is exactly what I have hear from those who have tried. often the stove manufacturer will sign off on it but the zc maker says no way because they have nothing to gain and allot to loose.

 

[thechimneysweep]

Inserts are a stove within a convective envelope. They are never going to reach near the potential temperature of a large, open fire in the ZC fireplace. If the insert mfg. approves the insert for ZC install and it fits without compromise, I am ok with this install.

first off, it has to be a ZC rated insert, secondly the structure has to support the weight thirdly most ZC's are connected to a UL 103(non HT) 1700F air cooled flue system which is death to draft for an EPA insert , so a reline MUST be done , on an exterior flue it likely should be an insulated liner.

Agreed, and agreed.

I've never seen a 0-can manufacturer who specifically allows installation of an insert. Never seen a masonry fireplace that specifically allows one either.

This should come as no surprise, given that there is no test protocol to list a given fireplace for possible future installation of an insert.

So, 0-can manufacturers simply state that they're not allowed, presumably to eliminate any warranty issues that might arise due to the installation. This doesn't mean installation of an insert in a 0-can is a code violation: it simply gives the manufacturer a hide-behind in the event that somebody's 800 lb. homemade insert squishes the floor.

There IS a testing / listing protocol to allow installation of a specific insert model in a 0-can, typically requiring a proper-size insulated stainless liner. If you buy one of these, and install it as specified in the owner's manual, your code authority has no grounds whatsoever to say the installation isn't up to code. The only downside is you will probably no longer have warranty protection for the 0-can, which typically didn't cover much anyway.

About the "squish factor": we've installed inserts as heavy as 650 lbs. in several different brands of 0-cans over the years, with nary a squish.

 

[begreen]

Thanks for the perspective Tom. Do you normally shim up the floor of the ZC so that the bulk of the insert weight is not sitting on the front flange of the fireplace?

 

[thechimneysweep]

Thanks for the perspective Tom. Do you normally shim up the floor of the ZC so that the bulk of the insert weight is not sitting on the front flange of the fireplace?

We might, BG, if the vertical plate seems flimsy. This allows the refractory floor to evenly distribute the weight of the insert, virtually eliminating the chance of damage to the 0-can..

 

[SimplifySC]

Thanks Tom. I am in full agreement. I don't think an insert or even more a hearthmount stove are safety issues. I think it is much more about the ZC manufacturer avoiding any liability. If it was a hazard, Jotul would not be so boldly offering instructions on how to do it and certifying it. After swapping notes with my sweep today, we agreed I should contact my local building inspector and show him the Jotul paperwork. If he blesses the hearthmount based on Jotul's installation specs (which includes running a stainless insulated liner in my existing Prefab chimney) then that means State Farm will cover it as well. If that is the case, I am leaning toward moving forward even without the blessing of Majestic.