Block off plate for zc fire place..is it nessesary?

[paulie]

Okay guru's if you put a insert into a zc fire place, "now float with me here" the fire place it self will work as a block off plate...correct? it is already totally closed off. So when going this route, a additional block off wouldn't be nessesary right?

 

[Hogwildz]

Fireplace is totally closed off? ventless gas????
IS there a chimney? what type is it?

 

[paulie]

yes, the fire place box is completely closed. It was a wood burning fire place "Heatilator" the only opening is where the pipe came into top of fire plce box. Therewas ofcoarse approx 8 to 10 inchs of luovers over the box on face of it, but they are now covered with the surround of the insert. but there is nothing open above the insert, you have the insert, and a offset adaptor, which is connected to the ss liner. Striat up from there 24' external chase

 

[Hogwildz]

If the pipe is the only opening in the top ( meaning no damper) I would think there would be no need for block off plate. As its job has already been filled
If there are any holes, gaps etc around the liner, then yes a pc of metal to close them off would be optimal. What is the liner? single, double wall, triple wall, If its triple, it should have air vents between the second & third layers. those you would have to leave unobstructed, as the triple wall has them for air cooling.

 

[paulie]

I am thinking they are triple, I do have two out side air vents that were installed in the chase with the original fire place, they said it would be nessesary for the fire plce to hace enough air

 

[paulie]

I am thinking they are triple, I do have two out side air vents that were installed in the chase with the original fire place, they said it would be nessesary for the fire plce to hace enough air

They installed a ss liner through the original pipe

 

[Hogwildz]

Is the s.s. liner inside the pipe, single wall, flex or double wall insualted?

 

[webbie]

Our guys used to put a trim ring up in the upper firebox that would have the 6" pipe go through it. But, no, we did not fabricate a typical block of for this type of job. If pipe was insulated, then there would be very little space around it and you could just stuff some extra insulation at the bottom to seal it decently.

 

[Hogwildz]

The man comes through.
What if its triple wall the liner is in? The triple wall shouyld not have the air vents blocked should it?

 

[paulie]

the new liner is a ss flex liner

 

[Hogwildz]

You could prolly just do as web said, out some kawool around any gap if any around liner and fab a trim ring to fit tight around.
If its tight enough 1/8" gap or so. Just get some furnace cement and fill the gap with it, or even better yet a small pc of 3/8" or whatever side you need rope or tape gasket for stove doors/ glass etc. Bottom line, if its already tight, its done.

 

[paulie]

You could prolly just do as web said, out some kawool around any gap if any around liner and fab a trim ring to fit tight around.
If its tight enough 1/8" gap or so. Just get some furnace cement and fill the gap with it, or even better yet a small pc of 3/8" or whatever side you need rope or tape gasket for stove doors/ glass etc. Bottom line, if its already tight, its done.

thanks man, ansewerd my question, I read alot about block plates and it just got me thinking.

 

[webbie]

Very few triple wall prefab chimneys are out there, but the ones that I am familiar with (Temco) did not connect into the firebox - each wall of the pipe connected to a wall of the fireplace assembly - So air came down the outer wall, around the fireplace(outer chamber), then up the fireplace inner chamber and back up the inner pipe......only the smoke from the fireplace went up the inner wall. So there was no connection between the smoke and convection air.

I have seen strange (unidentified) prefab fireplaces that had some cooling vents built in - in strange places. This is the exception as opposed to the rule. Most are pretty standard.

Most Prefab ZC for the last decades have been double wall pipe - not triple - and the fireboxes are double also. These cost a lot less to manufacturer. These fireplace usually take their cooling air UP the second wall, and that air comes from the chase. The fireboxes cool themselves separately from the air convecting around them (in the bottom vents and out the top).

 

[Hogwildz]

U da man Craig

 

[DiscoInferno]

Most Prefab ZC for the last decades have been double wall pipe - not triple - and the fireboxes are double also. These cost a lot less to manufacturer. These fireplace usually take their cooling air UP the second wall, and that air comes from the chase. The fireboxes cool themselves separately from the air convecting around them (in the bottom vents and out the top).

One exception is the Majestic WMC42, which has (or at least is supposed to have) a triple wall chimney. If I recall, cooling air enters between the outer and middle layers at the top, flows down to above the fireplace, picks up heat, then flows up between the inner and middle layers and back out the top. Seems to keep the inner pipe warmer, no creosote at all so far. The smaller WMC36 can have a double wall chimney instead, according to the manual.

My Ultima, on the other hand, is double wall like you describe. For air-tight chases it even has a hookup for a chimney OAK.

 

[webbie]

Yeah, Disco - I do remember seeing certain prefabs that had weird setups like that.....vents up in the upper part of the firebox.

One of the many reasons I would not use tight fitting insert surround panels (or a low fitting block off) in a ZC.

 

[Elderthewelder]

I was under the impression one was not suppose to cover up the cooling vents/louvers on a zc when instaling a insert. This has been posted on this board in the past. Actually I am reading my install/owners manual right now and it say's "all convection vents and louvers must be left unmodified and uncovered"

pic of my insert in a Majestic ZC

 

[DiscoInferno]

Yeah, Disco - I do remember seeing certain prefabs that had weird setups like that.....vents up in the upper part of the firebox.

One of the many reasons I would not use tight fitting insert surround panels (or a low fitting block off) in a ZC.

The chimney cooling is completely separate from the firebox cooling, sorry if I gave the wrong impression. Only the 8" inner pipe penetrates the outer shell of the fireplace, while the firebox draws air in the bottom grill and blows it out the top. I think it's pretty standard except for the third chimney wall, the Superior-brand prefab I replaced with the Ultima was similar.

 

[paulie]

so are you saying this is a improper install ? with vents covered. The shop knew this had louvers, and said they do them all the time this way.

 

[jtp10181]

We install them like that also, if the panel is not tight against the box and it doesn't have insulation in it the cooling vents could still circulate fine I think.