What does overfiring a circulating prefab ZC fireplace look like?

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Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
I have been told that these ZC prefab fireplaces are much less capable of handling larger fires than their ZC wood stove insert counterparts. If I were to start a fire, close the sealed doors on such a fireplace, open the outside air intake, and just let the fire burn, at what point should I consider the fire to be too large (and therefore need to restrict outside airflow or open the doors to let it cool off)? I have seen example fires in ZC wood stove inserts that look like infernos, but i'm assuming I could not let the fire get that big / hot in a ZC prefab fireplace.

Anyone have any examples, possibly a video, on what an acceptable size fire is in one of these prefab units?

Here's an example unit: https://www.heatilator.com/products/accelerator-wood-fireplace
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,675
South Puget Sound, WA
I don't have any pictures. Did you try a google search? Some ZC fireplace manuals specifically say that they are not for full-time heating. And some people never read the manual. :mad:
 

Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
I don't have any pictures. Did you try a google search? Some ZC fireplace manuals specifically say that they are not for full-time heating. And some people never read the manual. :mad:
I did, I didn't really see anything, there were some examples for stoves but nothing for these cheaper ZC fireplaces which i'm assuming cannot have fires like those in a stove. I was trying to find a video example but surprisingly there is nothing out there. I was thinking someone here might know where I could find something like that. And as far as I can tell, my manual mentions nothing about not using it for full time heating.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,573
central pa
I did, I didn't really see anything, there were some examples for stoves but nothing for these cheaper ZC fireplaces which i'm assuming cannot have fires like those in a stove. I was trying to find a video example but surprisingly there is nothing out there. I was thinking someone here might know where I could find something like that. And as far as I can tell, my manual mentions nothing about not using it for full time heating.
Do you have the heatilator accelerator
 

Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
Do you have the heatilator accelerator
Yes I do, sorry, I should have been more specific about that. My builder is installing it in my new house which is under construction.

I tried to go a different route with the fireplace once I found out these units were not very good at actually providing heat, but it was too late. So now i'm just trying to figure out the do's and don'ts of this unit. I do have a lot of the upgrades like the regulated outside air intake, gasketed doors, and blower, so that is nice, but I understand it is still a limited setup.
 

kennyp2339

Minister of Fire
Feb 16, 2014
5,956
07462
The manuals on both the unit and chimney will say not to run the zero clearance fireplace continuously, its not a one fire at a certain temp, its a fire that is ran more then (I think 8 hours without giving the unit a full cool down) this is because the chimney is a double wall air cool and not a full class a all fuel (double wall insulated or triple wall air cooled unit)
 

Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
The manuals on both the unit and chimney will say not to run the zero clearance fireplace continuously, its not a one fire at a certain temp, its a fire that is ran more then (I think 8 hours without giving the unit a full cool down) this is because the chimney is a double wall air cool and not a full class a all fuel (double wall insulated or triple wall air cooled unit)
I read through the manual for the fireplace again and I still don't see where it mentions that, I must be missing it. That does make sense with the chimney, It's understandable that a standard air cooled would not be able to run 24/7 non-stop. I am still curious as to what size fire these types of fireplaces can handle, even if they can only run for 8 hours.
 

EbS-P

Minister of Fire
Jan 19, 2019
1,242
SE North Carolina
read through the manual for the fireplace again
I did not find any burning time mentions either. Did you read the chimney manual? In fact it says add minimum of three average size splits.
Common sense is my suggestion. After you burn awhile you will know when it’s not looking or sounding right.

Then next question is what do you do when you notice an over fire situation in a zero clearance unit?
 
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Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
I did not find any burning time mentions either. Did you read the chimney manual? In fact it says add minimum of three average size splits.
Common sense is my suggestion. After you burn awhile you will know when it’s not looking or sounding right.

Then next question is what do you do when you notice an over fire situation in a zero clearance unit?
Three splits sounds reasonable. Just curious, where are you all finding the manual for that chimney? I only have been able to find the manual for the fireplace itself.

In the case of an overfire situation, I've read that you should just restrict the air intake or open the doors for a wood stove, i'm assuming the same holds true for a ZC.
 

EbS-P

Minister of Fire
Jan 19, 2019
1,242
SE North Carolina
I guess you could always go down the path of monitoring flue gas temps. I use an Auber AT200 that has a temp alarm.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,675
South Puget Sound, WA
I did not find any burning time mentions either. Did you read the chimney manual? In fact it says add minimum of three average size splits.
Common sense is my suggestion. After you burn awhile you will know when it’s not looking or sounding right.

Then next question is what do you do when you notice an over fire situation in a zero clearance unit?
Not every ZC fireplace has this caveat. Some of the cheaper contractor grades do and going way back I thought the early BIS fireplaces did too, but I no longer have those manuals. When in doubt, read the manual.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,675
South Puget Sound, WA
I was just looking at the Mark 123 Heatilator 3138EP manual that has the caveat that this unit is only for supplemental heating and not for full-time heating use.
 
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john26

Minister of Fire
Oct 27, 2008
553
Wildwood MO
There was a posting last year I believe by a member from San Francisco I believe with a ZC that was over used or overfired. He had pics best I remember he said it was like 10 years old and burned it everyday in the winter, not sure if anyone could find that post.
 

kennyp2339

Minister of Fire
Feb 16, 2014
5,956
07462
The manual also states that you can install a wood burning insert into the fireplace as long as the air vents on the zero clearance unit are not blocked or altered in any way, so if you install the fireplace and want to upgrade in the future you have an option without going through all the pains of ripping everything out and starting over, just an insulated liner and a 2 cu insert.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,573
central pa
The manual also states that you can install a wood burning insert into the fireplace as long as the air vents on the zero clearance unit are not blocked or altered in any way, so if you install the fireplace and want to upgrade in the future you have an option without going through all the pains of ripping everything out and starting over, just an insulated liner and a 2 cu insert.
According to some in the industry that is about to change so it would have to be done quickly if that is the intent. Supposedly ul is going to make it so inserts will not be allowed on zero clearance units because there really is no test procedure for that.
 
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EbS-P

Minister of Fire
Jan 19, 2019
1,242
SE North Carolina
There was a posting last year I believe by a member from San Francisco I believe with a ZC that was over used or overfired. He had pics best I remember he said it was like 10 years old and burned it everyday in the winter, not sure if anyone could find that post.
I kinda remember that or a similar one. It was obvious that major damage had occurred. Fireback materials had completely failed. But those are replaceable and might need replacement after a decade even if used according to manufacturers instructions. I can’t remember if other parts were damaged I’m guessing they were. I don’t think it’s super relevant only because if you are concerned now you would never let it get to that point with out noticing the damage and addressing it. Prevention is better than reaction. Not throwing logs in against the back not leaving a new load of wood unattended (keep a kitchen timer near the fireplace or use use phone and set a timer after each load. )
 

kennyp2339

Minister of Fire
Feb 16, 2014
5,956
07462
I was at 3 different fire scenes a few years back with the source being the zero clearance unit, one was technically a chimney fire. the air cooled pipe was in a wooden chase, the chase burned through, along with the whole side of the house, inside and out
The second fire was from an older builders grade fireplace, the guy said he was burning it for 3 days during the holidays, the unit after we overhauled it was clearly cracked right at the top by the chimney collar, they to lost the house from fire, smoke and water damage, 3rd one was from melted wiring that powered the blower, unknown if he wire was melted from resting on the stove body, or if the wire was chewed by a mouse or something, either way, they to lost 90% of there house and belongings.
Those are the reasons why I dont like those fireplaces, the epa zero clearance units are built much better and use class a chimney pipe which is a much safer product and rated up to 2100 deg f which can be experienced during a chimney fire, but if you keep your pipes clean then you would have to worry about that either.
 

Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
I was just looking at the Mark 123 Heatilator 3138EP manual that has the caveat that this unit is only for supplemental heating and not for full-time heating use.
That's a different model from the one I posted though right? Or is it the same model just under a different name?
 

Braxvang

New Member
Aug 14, 2021
29
Virginia Beach, VA
The manual also states that you can install a wood burning insert into the fireplace as long as the air vents on the zero clearance unit are not blocked or altered in any way, so if you install the fireplace and want to upgrade in the future you have an option without going through all the pains of ripping everything out and starting over, just an insulated liner and a 2 cu insert.
Hmmm, I did not realize that, that might be my best option at this point since it's too late to change the fireplace.
 

john26

Minister of Fire
Oct 27, 2008
553
Wildwood MO
The manual also states that you can install a wood burning insert into the fireplace as long as the air vents on the zero clearance unit are not blocked or altered in any way, so if you install the fireplace and want to upgrade in the future you have an option without going through all the pains of ripping everything out and starting over, just an insulated liner and a 2 cu insert.
I did not see that in the manual. I called Heatilator in the past about a ZC E39 "This fireplace has been tested and listed for use with the optional components listed on page 5" in the manual but did not list wood burning inserts. They said a Buck 18 was ok if the fire place was not altered other than un bolting the flu damper.

Capture.PNG
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,675
South Puget Sound, WA
I did not see that in the manual. I called Heatilator in the past about a ZC E39 "This fireplace has been tested and listed for use with the optional components listed on page 5" in the manual but did not list wood burning inserts. They said a Buck 18 was ok if the fire place was not altered other than un bolting the flu damper.

View attachment 281737
It's model specific. Always read the documentation. If the intent is to install the insert and their support gives the ok, I would get the statement from Heatilator in writing.
 
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