Installing a block-off plate with a Heatform fireplace

[bobanlou]

We are purchasing a Quadrafire 4100I fireplace insert. We have a central (inside the house) brick fireplace with a metal Superior Heatform firebox (installed in 1975 when we built the house). The Heatform has 4 tubes at the top. We'll need to cut one or two of the tubes as well as some of the metal at the back of the firebox for the full-chimney-length stainless steel liner to come down through. (the chimney is currently lined with 12x12 clay tiles) Has anyone had any experience with this situation? If so, how did you create a block-off plate and where did you insert the plate? Thanks in advance for any help.

 

[bambam]

I recentyl installed a Quadrafire 4100I with a 6" liner and I only put insulation at top of chimney with a plate over that to keep water from hitting the insulation. I am planning on putting insulation at the bottom of the chimney as a soft block-off plate. I think I am loosing a lot of heat up the chimney between the 6" liner and the 12" pipe that was the i.d. on the double walled chimney that I installed for the Majestic zero-clearance fire place. My plate at the top only covers the space between the 12" pipe and the 6" liner that allows the 1" space between the 12" and 14" o.d. to be open which is what insulates the chimney and allows you closer clearance to combustible material than a single pipe.

 

[DAKSY]

I've had to cut some of those tubes out & in lieu of a block off plate,
we simply stuff unfaced fiberglas insulation into the area around the SS liner...
No, it doesn't burn...
No, it doesn't melt...
No, it doesn't emit toxic substnaces that kill animals or children...
It's a WHOLE lot easier & cheaper than fabricating an irregularly shaped
plate that needs to be fastened & sealed.
You should use the fiberglas UNDER the cap plate, also, to create
a column of standing air in your chimney, which will act as insulation...
Others will surely disagree, but that's my story & I'm stickin to it!

 

[Jake Weaver]

My house was also built in 1975 and I also have the same Superior Heatform heatbox. I put the block off plate below the tubes right at the damper. I used self tapping screws and connected it to the sides of the metal. I had to cut one of the tubes to get the 6" liner down. I covered the pipe with a piece of metal where the pipe comes into the room.

 

[bobanlou]

Daksy, your response mirrors that of my husband. But I do worry about those very things you mention: melting/burning insulation (if it is fiberglass) and toxic fibers if it is unfaced ceramic wool, especially since we have three small grandchildren that visit frequently.

What can I say? I'm a worry-wart and read all the manuals, etc., etc. My husband is the type of guy that never reads the installation manuals (which occasionally leads to less than optimum results) and never asks for directions! But we do welcome your input and that of others on this forum.

 

[bobanlou]

Bumping this topic to see if anyone else has input?!?!?

 

[stejus]

My chimney sweep installed fiberglass all around the damper area where the liner passes through. It was in there this past season (Jan through Apr). I had to remove it becasue I had the chimney lined with "pour in" insulation. When I went to remove the fiberglass, it looked brand new as when it went in. There were a few sections that hardened where the fiberglass was touching the liner. It wasn't much at all. I didn't smell it or notice any fiberglass fibers on the stove top either.

I plan to re-install some fiberglass in the damper area because the insulation he poured in stops at the first clay flue tile. This leave the smoke shelf and damper open to the room. Once I close off the damper area with fiberglass, this will keep the heat from entering the smoke shelf area.

 

[Todd]

I have the same fireplace and some day will do an insert, when I do I will either stuff the damper area with rock wool insulation (which would be easier) or a block off plate. I also plan to cut all the tubes so any heat trapped inside the fire box has a place to exit into the room. I'd sure like to see some pictures of what you end up doing with yours.

 

[Dustin]

Bumping this to the top...also curious what you ended up doing..i have the same issue here.

 

[VCBurner]

I put a stove in my fireplace last year. My block off plate is made of 24g steel. I was on a job where the tin knockers were pretty nice so I asked them if they could have the shop fabricate a plate out of tin. I gave them the measurements so the plate would right below the old fireplace damper. I'm thinking of putting mineral wool insulation above the piece of tin. I would also use fire calking to seal any possible air leaks. I like your set up, very nice!! keep us posted and burn on!

 

[zzr7ky]

Hi -

My install is the same. I measured carefully and cut the back (forward sloping section of the firebox so I had a straight shot up the flue tiles. I used a 4.5" cut off wheel as i didn't have a torch handy. It took about 5 minutes with a hammer drill to clear the mortar/brick rubble from behind the firebox with a small hammer drill. This worked out well for me because I went with rigid vent and didn't have to use any flex. I just used RTV silicone and then bolted the damper assembly shut. Works like a champ.

I think I used a 3# coffee can to make a template to mark where to cut.

ATB,
Mike

 

[bobanlou]

In September we had our installer cut out the damper and as much of the tube section as was required to get the stove pipe through to the stove. A block off plate was installed at the top of the chimney and the area where the stove pipe entered the clay liner was stuffed with rock wool. The two tube sections of the old Heatform which were cut, were sealed off. That left two functional tubes which help to move the heated air around the stove insert out into the room. If we want, we can turn on the old Heatform fans to augment the blower on the stove. However, the Quadrafire blower works great and we haven't had to use the old fans.

We are extremely happy with our fireplace insert. It has made our living room a very cozy place on these cold winter nights!