RSF Opel III Installation question

[annb]

Hi,

We finally decided to order the Opel III and it finally arrived, albeit not as fast as we'd hoped We skipped the Black Friday madness and began the installation today ... not that we needed much of an excuse to skip the shopping. Now, we've encountered our first installation challenge.

The fireplace is going into a corner on the main level. We have a two story house. We need to tuck the chimney as far into the corner as possible in order to clear the cast iron, clawfoot bathtub on the second story. The chimney installation instructions state that we must have an opening not smaller than 13". With a 13" opening tucked into the corner of the first floor ceiling, we can just clear the tub. However, the radiation or heat shield has a flange that is larger than 13" square. It is actually 16" square. Think of a top hat where the barrel of the hat has a diameter of 12" and the brim has a diameter of 16" (only this brim is square rather than round).

So, we are wondering if we can trim some of that brim as long as we maintain the 13" opening and 2" clearance around the chimney. As far as we can discern, and we don't know much, the flange simply provides a way of attaching the radiation shield.

Can anyone with experience comment on the whether or not this would be safe? Again, we could maintain the proper sized opening and the required 2" clearance around the pipe.

Thank you! Hope you all had a Happy Thanksgiving.

 

[LLigetfa]

Would not the flange (or brim as you call it) be at the bottom of the radiation shield and sit up against the ceiling above to stove? Its purpose is to shield the joists through the ceiling/floor penetration. Are you going to run the radiation shield up past the tub to the ceiling above the tub?

 

[annb]

Thanks for your response. Yes, the flange will be on the ceiling above the stove. It will go through the ceiling giving added safety where the chimney passes through the ceiling/floor, as I understand it. The flange is 16" square. The plan is to utilize elbows to allow the chimney to get as far into the corner as possible. With the flange, as is, that means the chimney will pass through the center of a 16" square. The instructions state that we need a 13" square through which the radiation shield and the chimney will pass. If we go through a 13" square, we clear the tub. If we have to go through a 16" square, we will not clear the tub. So, we're wondering if we can trim, or bend two sides of the flange to allow the chimney to pass through the ceiling closer to the corner, while still honoring all required clearances. Does that make sense?

Thanks.

 

[LLigetfa]

I understand the minimum opening through the ceiling is 13" x 13" and the additional 1.5" flange width is so that a firestop gasket seal can be made at the ceiling.

 

[LLigetfa]

I'm trying to understand why there is not the 1.5" of clearance for the flange. The 13" x 13" is the minimum clearance through the boxed opening in the ceiling WITH the radiation shield. Below the ceiling without radiation shield, you want the additional 1.5" clearance as well as the firestop gasket seal.

 

[annb]

The chimney instructions don't say anything about a gasket seal at the ceiling. They simply state that the radiation shield should be inserted from below and screwed into place. There is no type of gasket or seal included nor mentioned.

As for the clearance, the chimney will go up through the ceiling of the first floor, through the floor of the second floor and up right along side the bathtub. It just clears the tub with the 13" square. A 16" square moves the chimney over just enough so that it doesn't clear the tub. The only option would be to look for another place to locate the fireplace, which of course, is not easy when we're going through living space on the second floor. But again, we want to be safe.

Thanks for your reply.

 

[LLigetfa]

Here is a pic out of my manual. The ceramic strips are soft and form to fill the gap. High temp silicone could be used as well. It stops flames from getting sucked into the joist cavity.

 

[annb]

Ok. I think that might be a difference in the Canadian and American requirements. My manual doesn't doesn't say that and my system did not include that ceramic seal.

 

[annb]

We decided to locate the fireplace on a different wall to allow the chimney to come up through a bedroom rather than next to the tub. It's not as nice of a location in the family room, but it will work and solve the problem. Thanks for your help. I'm sure we'll have more questions as we go along

 

[LLigetfa]

Firestop aside, the main purpose of radiation shielding is to be able to reduce clearance to combustibles. Since the shield is required to allow a 13" x 13" opening in the joist cavity, greater clearance should be provided below the firestop at the ceiling if there is no radiation shield. Keep in mind that convection will occur along the first floor chimney section, culminating with a buildup of heat where vertical transitions to the horizontal ceiling. If you have clearances too tight for the 1.5" flange, I would be worried about excess heat between the chimney and wall.

I'm not an advocate of building to minimum code. In the pic I posted where it specifies a 1 hour fire rated enclosure, I chased my chimney using metal studs, drywall, cement board firestops, and I ran radiation shield the length of the chase. That gave me piece of mind knowing it as above minimum code should the chimney ever deteriorate from multiple chimney fires.

Do you intend to build tight to minimum clearance below the ceiling where the stove is without additional radiation shield? I don't know if US code requires the same 1 hour fire rated enclosure or not but surely you must plan to shield the hot chimney where it runs close to the tub. How do you intend to chase in the chimney upstairs by the tub and how will it be both aesthetic and meet the 1 hour fire rating if required?

 

[annb]

I appreciate all of the good info. It really is helpful. As I said in the previous post, we decided to move the location of the fireplace. It was going to go into a corner and up through the bathroom, next to the tub. Now, it is in the middle of the wall and will go through our bedroom. The manual that came with our Opel does not say anything about a 1 hour fire rated enclosure. It only mentions maintaining a 2" clearance to combustibles.

We were planning to frame out the fireplace with an additional 12" on each side of the fireplace. The clearances will significantly exceed the minimum requirements. On the second level, we'll frame out the chimney. We're planning to use the fire rated drywall. But, we want to do this safely, so if there's a better way, we'd like the specifics.

Thanks! BTW, we have a GSD as well. We love those dogs.