Insulating a SS Liner Using Perlite / Vermiculite

Insulating a SS liner using perlite / vermiculite

PostBy: Cap On: Wed Nov 01, 2006 11:17 pm

I posted under the General Question catagory some concerns I still am having with a strong draft on warmer or damp days. Greg ,aka LS Farm mentioned the idea of removing my ss liner and insulating it. This would be impossible in my installation due to a 6" liner snuggly fit into a 8" telacotta square flue. But I have an idea! :idea:

I work in the cryogenic industry. I should be able to obtain many bags of perlite. Perlite is for the most part the same as vermiculite. Vermiculite is used as an insulator in furnaces, flues , etc. It is fireproof, rot proof, & very plentiful so I don not expect the cost to be much. I have worked with perlite. It is a grain like mineral which is very light. We use it to insulate cryogenic tanks. I have literally topped of large vessells with multiple bags of perlite. We simply hook up a vacuum pump to the valve at the bottom of the tank, and allow the vacumm to suck the perlite into the voids from the vacuum plate at the top of the tank. The wind will easily blow it away thus the reason to suck it in.

I could pour or suck the perlite into the corners of the square tellacotta to help insulate the ss liner using a shop vac for suction or simply a large funnel.

Has anyone ever seen or heard of this before? Richard, Greg?
Hand Fed Coal Boiler: Harman SF 250, domestic hot water loop, heat accumulator

Insulating a ss liner using perlite / vermiculite

PostBy: Tom On: Thu Nov 02, 2006 11:52 am

I moved during the summer and decided to go with an Alaska stoker instead of moving my Hitzer 50/93. I read many people's opinions on the need of lining a terra cotta lined chimney. Alaska's manual suggests piping into the terra cotta chimney just past the existing old fashioned damper and insulating the balance of the gap for an air tight fit. I decided to have a contactor take a look. Of course, he suggested lining from the stove to the cap for a better draft. He suggested using something similar to perlite as an insulator also because of lack of space to wrap the liner. He also said he would mix the perlite with mortar. I decided against the mortar and perlite due to if I ever needed to remove the liner in the future. I plugged the gap where the liner enters the terra cotta liner just above the stove and plugged the top just inside the cap with ceramic insulation. I'm getting great draft even on the stoker's "low fire" setting in these 50 degree days we've had, including a 62 on Tuesday. The chimney is a typical brick exterior, terra cotta interior and was built in 1958. However, this was an experienced installer who suggested it. Maybe you're onto a good idea.

PostBy: LsFarm On: Thu Nov 02, 2006 9:35 pm

If you can keep the insulation dry, then any amount is better than none. The problem is that if the poured in insulation gets wet, then it will be less effective than an air space. The wet perlite would probably conduct heat away from the liner rather than insulate it.

So if you can seal the top of the chimney really well, I'd give it a try.

I'd try Tom's idea first, insulate the top and bottom and see how it affects the draft, Then insulate the whole liner if you like the intial results.

Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

PostBy: lime4x4 On: Thu Nov 02, 2006 11:34 pm

it's odd that you have a strong draft when it's warm out it's uausually the other way around poor draft when warm good draft when cold.I have the 6 inch ss liner as well.I insulated the bottom and the top.My chimney is located inside my house so that probably plays a big part.

PostBy: LsFarm On: Thu Nov 02, 2006 11:44 pm

Hi John, the problem Mark [Cap] is having is 'not' having a strong draft.

His post doesn't exactly say that, but we have been exchanging PM's and that is the problem.

With his stove turned way down for warm weather he isn't able to maintain strong enough of a draft to keep the fire going.

How's your coal burning going this year??

Greg L
Stoker Coal Boiler: Axeman Anderson 260
Hand Fed Coal Boiler: Self-built 'Big Bertha' SS Boiler
Baseburners & Antiques: Keystone 11, Art Garland

PostBy: lime4x4 On: Fri Nov 03, 2006 12:12 am

Oh.trying to get a chimney to draft decent when it's warm out is tough.
Good started the stove first week of oct and it's been going none stop.
It sucks thou temps in the upper 60's in the day and 25 to 35 at night. I've found that since I have the combustion blower going non stop I can maintain a fire when it gets warmer out.Since it's always blow air into the fire box that helps with getting a decent draft going.

PostBy: Always learning On: Tue Nov 07, 2006 3:53 am

I'd have the insulating material tested for any asbestos content before using it. If you ever sell the place and a buyer's inspector observes the perlite, he or she may recommend analysis for asbestos. If it turns out to be an asbestos containing material, you'll probably be saddled with the responsibility and cost of having it removed and disposed of in accordance with all applicable federal, state, and local regulations and protocols.
Always learning