Insulating interior prefab chase on exterior wall question - pic heavy

[PeteD]

I have a corner interior chase from which I just removed my Heatilator pre-fab fireplace in preparation for a Lennox Brentwood with class A ASHT+ chimney.

The interior wall of the chase was insulated, but not the exterior walls. Was this appropriate for the air-cooled chimney that was previously installed when the house was built.

Now, I want to insulate the exterior walls (I think). Should I keep the insulation on the interior wall as well?

Lastly, I have some exposed foundation (land rises behind house) behind one part of the fireplace. What can use to insulate that without trapping moisture or creating other problems?

Thanks,
Pete

 

[jtp10181]

All exterior walls should be insulated and drywalled just like every other exterior wall of the house, otherwise you have a weak spot behind the fireplace that will cause cold drafts to come in. The foundation wall should be dealt with just like if you were to finish off the hole basement. I am not sure exactly what is normally done here but I have been told insulation with no vapor barrier and then drywall.

 

[PeteD]

Thanks!

I am leaning towards rigid foam board for the foundation pony wall (which is about 2.5 feet high) with drywall over it, since I don't have room to frame it for fiberglass.

I suppose I can (should) leave the insulation on the wall above the fireplace between the chase and the room, right? I will need to cover this with drywall also.

Out of curiosity, were uninsulated walls in the chase appropriate for an air-cooled chimney installed in 1993?

Pete

 

[jtp10181]

Appropriate? No.
Common? Yes.

In this region it was not until about 6 years ago or so where people started to catch on that fireplaces are made to be installed INSIDE the house, not as a window.

I have been told the interior walls of the chase should be left open, this will allow heat from the house to transfer to the chase easily and keep it warmer. The insulation on the exterior wall will keep the cold draft out. Also you don't want to leave insulation batts just sitting in the stud there, what happens if they decide to fall out, or worse yet if they get a little wet (and heavy) then decide to fall out. Old wet insulation smells really nice when heated . If you find there is unsecured insulation anywhere put up some banding or tiger teeth to hold it in place for good.

 

[PeteD]

Appropriate? No.
Common? Yes.

In this region it was not until about 6 years ago or so where people started to catch on that fireplaces are made to be installed INSIDE the house, not as a window.

I have been told the interior walls of the chase should be left open, this will allow heat from the house to transfer to the chase easily and keep it warmer. The insulation on the exterior wall will keep the cold draft out. Also you don't want to leave insulation batts just sitting in the stud there, what happens if they decide to fall out, or worse yet if they get a little wet (and heavy) then decide to fall out. Old wet insulation smells really nice when heated . If you find there is unsecured insulation anywhere put up some banding or tiger teeth to hold it in place for good.

That makes sense about letting heat in, which is why I was asking. I will remove the inner wall insulation. Also, I will also cover all insulation with drywall to seal it in the wall and prevent it from falling on the fireplace.

Speaking about stuff on the fireplace and inappropriate installation methods, check out what I found during demo:

Here are the contents of the box that was sitting on the fireplace:

Somebody obviously thought on top of the fireplace was a good spot for trash!!

Thanks,
Pete

 

[begreen]

Yikes! You are saving the house! I can't believe the lack of thought and consciousness of some contractors. Makes me sick to see things like this.

 

[PeteD]

I hear you. Luckily, because this unit was so inefficient and basically just sucked the heat out of the house, it has barely been used by any of the owners of this house.

I have not used it since we had children and only used it 3 or 4 times before that in the several years we have owned the house.

Some people just don't think or care...

Pete

 

[cac4]

far out. I live in Northeastern MA, have a house that was built in 93/early 94, with a heatilator fireplace inside a wood chase that only sucks heat from the house, is quite drafty, and has been seldom used. I bet it was installed by the same guy. I wanted to yank the thing out, anyway, make a closet out of the space, or something, as a "real" fireplace wouldn't be practical for me...seeing that box of yours makes me REALLY want to yank it out! :bug:

what I'm wondering, though, is how do you actually go about doing that? Just cut the drywall out around the front, detach the pipe, and pull?

 

[PeteD]

This will give you the idea, but remove mantel, demo brick, pull/unscrew panels off fireplace, cut pipe with jig saw or Saws-all with bimetal blade, pry it upwards while pulling out fireplace, then pry off sections of pipe. Once I got to the outer elbows off, the inner chimney slide down in sections for removal. I have not done the outer pipe from the ceiling upwards, yet:

I should probably start a project thread to follow the progress. I always like to see those types of things photo-documented.

Pete

 

[cac4]

yeah, that looks very similar to what I have. side panels might be a little wider...it says "H36" on the tag.

my surround is simpler, though. just a single row of tiles to pry off. no "bricks".

we're practically neighbors, btw.

 

[DiscoInferno]

I had a prefab unit yanked out a few years back to make room for the Ultima. Lots of sawzall work. The chase was the same as yours, and I didn't improve it any. I took the lazy/cheap way out and used the air-cooled option for the chimney as well. Draft and creosote haven't been issues, so I got lucky. (Not so cold here, which helps.)

As for inappropriate items on top of fireplaces, we discovered that someone had blown or packed in a bunch of vermiculite or similar loose insulation around the whole prefab assembly. I'm assuming that was completely unsafe; certainly the Ultima manual prohibited insulation from touching pretty much anywhere. I had burned maybe 5 cords in that fireplace each of the two previous years, luckily I had hooked up double blowers so the thing didn't overheat.

 

[PeteD]

cac4, when I saw your post with the exterior of your house, I said to myself, that house looks like it could be on my street....I am up on a hill also, as can be seen from my roof:

 

[jtp10181]

Wow... if anyone had made any major fires in there that cardboard would have lit up and... that would have been bad. Fire would spread to the roof in no time and you would be screwed.