Cut out heatform myself?

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Tjm

New Member
Feb 25, 2021
59
Western NY
Bought some roxul I was going to line the inside of the heatform with but noticed the breathing/ dust concerns on the package so thinking if I use that I should prob block off the original heatform vents after all. Or not use the insulation and just stick with the steel plate/chase. Also think I’m going to ask the installer if they can use a double wall elbow off the back of the stove since that would be the only non insulated point in the whole system.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
Bought some roxul I was going to line the inside of the heatform with but noticed the breathing/ dust concerns on the package so thinking if I use that I should prob block off the original heatform vents after all. Or not use the insulation and just stick with the steel plate/chase. Also think I’m going to ask the installer if they can use a double wall elbow off the back of the stove since that would be the only non insulated point in the whole system.
There is no reason to use double wall there. And double wall isn't rated to be buried or listed for use with the liner system. It you block off air flow in your case where the back wall is not exterior I don't see a benifit to insulating the cavity. If it was an external chimney then yes absolutely
 

Tjm

New Member
Feb 25, 2021
59
Western NY
There is no reason to use double wall there. And double wall isn't rated to be buried or listed for use with the liner system. It you block off air flow in your case where the back wall is not exterior I don't see a benifit to insulating the cavity. If it was an external chimney then yes absolutely
I was just thinking it might be one more layer of protection since I cut out a 3/16 plate and I technically don’t know how thick the masonry is behind.
 

EbS-P

Minister of Fire
Jan 19, 2019
1,259
SE North Carolina
Not yet… Chimney was tarped off for rain after they poured the crown and I realized in a hurry without the draft sucking out the dust it was even more dirty than before! Got some nice sawzall blades to try. Hopefully later today. Also probably going to grab my pneumatic 3” cutoff tool or body saw back from my buddy to do the back side-to-side cut.
I put a box fan up top and it was quite effective. Almost so dust.
 
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Tjm

New Member
Feb 25, 2021
59
Western NY
The box fan worked amazing! As did the carbide sawzall blade. Cut like butter. I just clamped the flopped over damper and cut theu that and the upper smoke shelf at the same time. Did the front to back cuts with the sawzall and then for the back side to side cut I scored it deep with the angle grinder and broke it off. I used 1” masking tape to mark the hole. Did t stick too well but it worked… I put the outside of the tape as my final size and then cut on the inside. Scores the outside and bent up that 1” as a flange I can screw to. Sides are bent up. Just have to finish the back.

E7227857-B176-45EE-B2C0-52835020D804.jpeg 5ED61C43-17B2-42F5-92B8-6CEE3FF13B7E.jpeg
 
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Tjm

New Member
Feb 25, 2021
59
Western NY
Think I’ve got a piece of 16 ga galvanized I can just cut and bent two wings fwd. have something to screw to everywhere except the front angles. Gotta either complicate my plate and add flanges or maybe attach a piece of angle on the back side of each side of the existing heatform. Plan is just self tapping screw la I think but guessing they’ll have to be predrilled at a minimum.
 
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Tjm

New Member
Feb 25, 2021
59
Western NY
just looked it up and I think galvanized is only good to 392F before it off gasses. Doesn’t seem like a good idea.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
just looked it up and I think galvanized is only good to 392F before it off gasses. Doesn’t seem like a good idea.
It will be fine there it won't see those temps
 

Tjm

New Member
Feb 25, 2021
59
Western NY
Bye the way…chimney work done. I think they did a real nice job… One was a roofline up rebuild and other was extended 4 ft to get past the peak of the house without funky chimney pipe. Crown and mortar still a bit wet on the two flue so that will still lighten up more.

CDB23E47-ADCF-4383-B3A5-63A2D6876CF8.jpeg 90D895D8-6355-430F-8378-85D527E7A103.jpeg BF494118-E8CC-40DC-A664-83EE136466F6.jpeg
 
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Tjm

New Member
Feb 25, 2021
59
Western NY
Another interesting find when pulling the old uninsulated liner… Mason pulled from above as I fed the ovalized part thru the old damper area and he called down that it was all clear when I was still looking at the liner in front of me. Turns out the liner was two pieces flanged together in the middle but the Self tapping screws used to attach the two pieces hadn’t pierced the inner wall so it was basically just pinched together like a set screw. Seems pretty lucky it never came apart while cleaning I’d say.
 

begreen

Mooderator
Staff member
Nov 18, 2005
89,794
South Puget Sound, WA
Amazing. Good thing you caught that in time.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
Another interesting find when pulling the old uninsulated liner… Mason pulled from above as I fed the ovalized part thru the old damper area and he called down that it was all clear when I was still looking at the liner in front of me. Turns out the liner was two pieces flanged together in the middle but the Self tapping screws used to attach the two pieces hadn’t pierced the inner wall so it was basically just pinched together like a set screw. Seems pretty lucky it never came apart while cleaning I’d say.
That is why screws should absolutely never be used in applications like that
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
I’m assuming a liner made from two separate ( 10 ft?) sections is a no-no. Seems ripe for failure.
It is perfectly fine if done properly.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
Ok. Probably would have been fine if the screws cut thru the male pipe I guess.
Again no screws. Screws are absolutely not the proper way to do it. The proper way depends upon the type of liner.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
Oh I missed that. Just saw the -if done properly -comment. How should two sections be connected?
With the splice designed for that type of liner.
 
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Tjm

New Member
Feb 25, 2021
59
Western NY
Bottom went to the stove and top up and out. You can see the crimp on the top collar where screw didn’t penetrate. Looks like it should have had a collar on the bottom side and then something like the screenshot attached To lock them together I’m guessing.
Wow. It’s been like that for 27 years…

83A67A76-DB70-4CE0-BD35-D124A7C2261D.jpeg E6BBEDFE-A696-44AC-9D10-D633F1D38BBC.jpeg
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
Bottom went to the stove and top up and out. You can see the crimp on the top collar where screw didn’t penetrate. Looks like it should have had a collar on the bottom side and then something like the screenshot attached To lock them together I’m guessing.
Wow. It’s been like that for 27 years…

View attachment 283421 View attachment 283422
That is heavy wall liner. It is the proper type of liner but should be attached with rivets not screws
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
25,670
central pa
And correct me if I’m wrong but even back in 1994 should have been insulated for a Masonry chimney with wood/framing touching it?
I believe so yes. That's a bit before my time in the industry
 
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