Seal between flue and conditioned space

[iron]

It will not be absolutely air tight no

Appreciate the insight. Fingers crossed.

 

[CanFireman]

With RSF Fireplace you have no choice but to use ICC pipe. That pipe requires ventilation. You’ll overheat at the penetration otherwise.

I don’t know of any way that you can seal this up completely without creating a fire hazard.

There are other chimney products that do allow you to seal the vapour barrier and to caulk the gap between the chimney and any fire stop. Unfortunately those products are not approved with RSF fireplaces.

 

[iron]

dang, that wasn't the response i was hoping for!

what are the other chimney products that work to accomplish this, or better yet, what other stove/FP manufacturers work for such a detail?

 

[CanFireman]

In the end, will come down to the appliance and what it is approved for. No sense in discussing the chimney until you have selected the appliance. With factory-built fireplaces, the manufacturer dictates what venting is approved.

Plenty of other FB Fireplaces out there — Valcourt, STUV, Spartherm etc. who make high-efficiency heating fireplaces. Look for one that approves a wider variety of chimney products. This will give you the freedom to pick a product that suits your needs.

With a bit of research, you can quickly see which chimney products are designed to address vapour barrier and caulking and which ones are not. Will be documented in writing within instructions. If unaddressed, you will have your answers.

If going with a freestanding stove, a ceiling support will be involved. This serves more than one purpose. Aside from allowing you to transition from stovepipe to chimney, it maintains clearances through the penetration. Some can also serve as the attic insulation shield.

With a factory-built fireplace, you won’t have any transition. Chimney is installed right off the top of the appliance. Penetration is usually addressed with firestop, AIS/ARS or a pass-through radiation shield.

 

[bholler]

With RSF Fireplace you have no choice but to use ICC pipe. That pipe requires ventilation. You’ll overheat at the penetration otherwise.

I don’t know of any way that you can seal this up completely without creating a fire hazard.

There are other chimney products that do allow you to seal the vapour barrier and to caulk the gap between the chimney and any fire stop. Unfortunately those products are not approved with RSF fireplaces.

A firestop is still required. It doesn't need ventilation it just says you can't fill the radiation shield or support box with insulation.

 

[iron]

With a bit of research, you can quickly see which chimney products are designed to address vapour barrier and caulking and which ones are not. Will be documented in writing within instructions. If unaddressed, you will have your answers.

I feel like I have researched a ton on this, but the information and product availability just isn't there. Stuv, looks ok, but their units do not have adjustable air controls, and are very $$$, so I don't see this being terribly practical.

Back to the drawing board, I suppose.

 

[iron]

If the issue at hand is truly a gap between combustible material and the chimney pipe, can I just frame in some cement board at the attic and have it come in tight to the pipe? Cement board is traditionally used for this purpose down low at the fireplace/stove box, so it seems it could serve a similar function up high, and then the typical 1-2" gap would only apply to wood framing and blown in cellulose insulation.

 

[bholler]

If the issue at hand is truly a gap between combustible material and the chimney pipe, can I just frame in some cement board at the attic and have it come in tight to the pipe? Cement board is traditionally used for this purpose down low at the fireplace/stove box, so it seems it could serve a similar function up high, and then the typical 1-2" gap would only apply to wood framing and blown in cellulose insulation.

Again you would use the factory supplied fire stop. There cannot be a gap at level changes

 

[iron]

I finally found the product, made by Duravent (attached). You can basically tape your air barrier directly to the insulated, airtight box. As far as I have found, this is the only product on the market for this application. Selkirk might have something, but it's not quite the same.

I have spoken with local building inspector, dealers, technical designers, and people on the board of WETT. There is a discrepancy in the Canadian Code (like US too) about needing to maintain an air barrier AND installing chimney pipe in accordance with manufacturer's requirements. For all pipes, except this Duravent one, there is typically a gap between the radiation shield and the firestop and what ends up happening is people will apply high temp silicone to close that gap. Well, the pipe is not tested for that condition, and thus it violates the UL testing of that pipe. Alternatively, you could leave the gap, but now you've violated your air barrier requirement.

Anyway, my choices for ZC FP's are now down to the following:

Elegance® 36

Experience the elegance and efficiency of the Elegance® 36 Built-in Wood Burning Fireplace. Perfect for smaller spaces, it delivers a powerful performance.

ambiancefireplaces.com

(broken link removed to http://www.spartherm-america.com/products/zero-clearance-fireplace-700/)

Prices are comparable. I like the look and performance of the Elegance better, but it requires either louvers on the front (not preferred) or ducted vents to both sides of the FP. Anyway, thanks for all the help. What a confusing topic.

 

[bholler]

I finally found the product, made by Duravent (attached). You can basically tape your air barrier directly to the insulated, airtight box. As far as I have found, this is the only product on the market for this application. Selkirk might have something, but it's not quite the same.

I have spoken with local building inspector, dealers, technical designers, and people on the board of WETT. There is a discrepancy in the Canadian Code (like US too) about needing to maintain an air barrier AND installing chimney pipe in accordance with manufacturer's requirements. For all pipes, except this Duravent one, there is typically a gap between the radiation shield and the firestop and what ends up happening is people will apply high temp silicone to close that gap. Well, the pipe is not tested for that condition, and thus it violates the UL testing of that pipe. Alternatively, you could leave the gap, but now you've violated your air barrier requirement.

Anyway, my choices for ZC FP's are now down to the following:

Elegance® 36

Experience the elegance and efficiency of the Elegance® 36 Built-in Wood Burning Fireplace. Perfect for smaller spaces, it delivers a powerful performance.

ambiancefireplaces.com

(broken link removed to http://www.spartherm-america.com/products/zero-clearance-fireplace-700/)

Prices are comparable. I like the look and performance of the Elegance better, but it requires either louvers on the front (not preferred) or ducted vents to both sides of the FP. Anyway, thanks for all the help. What a confusing topic.

What gap are you talking about? None of the products I use say you can't caulk the firestop to the chimney.

 

[iron]

What gap are you talking about? None of the products I use say you can't caulk the firestop to the chimney.

All of the products I looked at specifically noted that you cannot close off the gap. ICC, for example. And others.

 

[bholler]

All of the products I looked at specifically noted that you cannot close off the gap. ICC, for example. And others.

The gap is less than 1/16" on jerimiahs that I use now. Ventis was slightly more. I never saw anything for either saying you couldn't seal it

 

[iron]

so i finally got a quote on the chimney pipe + radiation shield + storm collar + fireplace adapter.

looks like duravent DTC will cost $3650. selkirk would cost $2875 (after a 25% discount they're able to offer).

thoughts between the two products? as far as i know, the duravent product has the only rated insulation shield that is meant to connect directly to the air barrier. however, as discussed in this thread, it sounds like most people don't care and they just taped/caulk it anyway and there is no issue.

either system is rated for the fireplace.

 

[CanFireman]

so i finally got a quote on the chimney pipe + radiation shield + storm collar + fireplace adapter.

looks like duravent DTC will cost $3650. selkirk would cost $2875 (after a 25% discount they're able to offer).

thoughts between the two products? as far as i know, the duravent product has the only rated insulation shield that is meant to connect directly to the air barrier. however, as discussed in this thread, it sounds like most people don't care and they just taped/caulk it anyway and there is no issue.

either system is rated for the fireplace.

Do what the installation instructions read. If you are unsure, contact the pipe manufacturer. You will see tech inquiry email for that very purpose. Providing you clearly articulate your question, you will get a fast reply.