Heatproof silicone and high temp stuff in tubes, what's good for stove reassembly?

[madcat]

Need to put the stove back together,I need some stuff to seal things up.when I took it apart it had some grey stuff in the seams that was hard and brittle.some sort of fire clay I presume.

A quick look at screw fix gives me the option of high temp silicone good up to 250 C , a higher temp stuff which sets hard by the look of it and tubs of fire clay.

 

The thing is that the whole job will have to come apart again ne xt summer. The new oven top hasn't arrived yet and I need a stove. The cracked oven top is getting a patch repair and being re used as is the old stove top.

What have you used and what do you recommend.

Edited September 5, 2013 by madcat

[nicknorman]

If you want high temperature silicone, try this:

http://www.hotline-chimneys.co.uk/fire-cement-smoke/high-temperature-silicone-black.html#Description

 

Good for 1200 deg apparently.

Edited September 5, 2013 by nicknorman

[madcat]

Thanks Nick,that looks good stuff.

They also sell Mad chimney cowls ,had to see what they are. Didn't live up to their name.

 

 

Anybody had problems using the lower temp stuff?

[canals are us?]

Thanks Nick,that looks good stuff.

They also sell Mad chimney cowls ,had to see what they are. Didn't live up to their name.

 

 

Anybody had problems using the lower temp stuff?

Yes!! I bought some from a chandlers and used it to seal the stove outlet collar to the fluepipe and after about 2 hours it started to expand, smoke, setting off smoke alarms and then burst into flames and burnt like a gas ring!! Never again. Replaced with fire rope packed into the gap and then fire cement. No problems then!!

 

James

[kevinl]

I've used this stuff and it worked OK for me, didn't turn into dust after a few weeks like the fire cement I bought from the chandlers and for a kilogram at the price you can't argue.

http://www.wilko.com/fireside-accessories/inglenook-fire-cement-1kg/invt/0245770

The only thing is it cost £4 and delivery is £3.50 but there is a store locatior on the website.

K

[Barry]

If you want high temperature silicone, try this:

http://www.hotline-chimneys.co.uk/fire-cement-smoke/high-temperature-silicone-black.html#Description

 

Good for 1200 deg apparently.

 

It does say it "Should not be used near the naked flame" which seems to be contradictory to the previous sentence which says it is suitable for flues, register plates, and stove doors.

 

I find that quite confusing

[nicknorman]

It does say it "Should not be used near the naked flame" which seems to be contradictory to the previous sentence which says it is suitable for flues, register plates, and stove doors.

 

I find that quite confusing

I guess it depends what you mean by "near". Actually in the edge of the flame, the temperature can probably exceed 1200. But in stove flue sealing application, there is no actual naked flame impinging on the silicone. Anyway, its worked on our stove flue without any sign of distress after a couple of winters.

[Richard10002]

I guess it depends what you mean by "near". Actually in the edge of the flame, the temperature can probably exceed 1200. But in stove flue sealing application, there is no actual naked flame impinging on the silicone. Anyway, its worked on our stove flue without any sign of distress after a couple of winters.

From the picture, I'm pretty sure that's what I've used on my flue joint and glass. I think it's called Envirograph and I got it from an EBay supplier.

 

Seems to have worked OK in all areas. I guess it's not in direct contact with the flames, (perhaps a little where it's squeezed out from behind the glass).

 

On first using the fire after applying the sealant it emits a worrying amount of smoke while it is curing, but this only happens on first use.

 

I've used it twice now - cant find anything else that is OK up to this temperature, and don't like cement.

[trackman]

Replaced failed fire cement in the stove firebox/flue joint last year with high temp silicone sealant (from B&Q I think). It's been fine through a very cold winter on our stove, the top of which was glowing dull red on a couple of occasions!

In my experience fire cement doesn't survive well with the vibrations of boating.

[Richard10002]

This looks like a tube of a softer cement that's "squirtable".

 

http://www.midlandchandlers.co.uk/Catalogue/ProductDetail/pyruma-cartridge-300ml-purimachos?productID=49502c3b-1508-4b15-a764-9b700cc1dfc9&catalogueLevelItemID=c6407d1a-aa40-4d13-8c35-86d3ff217701

[john6767]

A similar question.

 

On the top out our stove I an not happy with the seal between the flange where the chimney connects and the stove top. Visually there is perhaps a 2mm gap part way round the flange. It is probably going to be quite hard to take it all apart and bed it on fire cement or high temp silicon, so I wondered what other suggestions there would be.

 

Working fire cement into the gap with a knife certainly seems possible, particularly the "softer" stuff above, but I was wondering it there is such a thing as thing are fireproof "string" that could be pushed into the gap before fire cement. Or any other suggestions?

[onionbargee]

people seem to go over the top with high temp silicones on here, the melting point of cast iron is 1175 - 1290 deg C. You don't need expensive stuff from NASA to seal a stove. You can get it at screwfix or toolstation. Or get a little toothpaste tube of it from Halfrauds.

[Québec]

We bought and used this high temp. sealant from Screwfix:

 

http://www.screwfix.com/p/mapei-mapeflex-firestop-1200-c-high-temperature-sealant-grey-300ml/25153

[Richard10002]

people seem to go over the top with high temp silicones on here, the melting point of cast iron is 1175 - 1290 deg C. You don't need expensive stuff from NASA to seal a stove. You can get it at screwfix or toolstation. Or get a little toothpaste tube of it from Halfrauds.

But how hot does the stove actually get. Plumba, which is one of the commonly recommended sealant, is rated up to 250C. Is that high enough. The next lowest I have been able to find is the 1200C stuff, which is obviously high enough. Is there one in between?

[Québec]

 

From http://greymetal.co.uk/operation.php

 

• To get the best results from your stove it is recommended that a wood stove thermometer be fitted to the flue pipe just above the stove. Most thermometers are magnetic and if attached to the single wall flue pipe just above your stove will give a good indication of the flue gas temperatures.

 

115 °C - 245°C (240°F – 475°F)

The flue gases should be in this temperature band for the safest, most efficient and most economical operation of your stove.

 

Below 115°C (240°F)

This is below the condensation point of wood gases and may cause the build up of tar in the chimney, darken the stove glass and result in the inefficient burning of fuel.

 

Above 245 °C (475°F)

Too hot. Heat will be wasted up the chimney. Excess heat may damage the stove (voiding the warranty) or may ignite an existing accumulation of tar, resulting in a chimney fire.

[DHutch]

We have used the orange "250deg" stuff when replacing/reassembling our sectional cast iron flue. The majority of joints are at the top, doglegging it out away from the handrail and sealing it round the roof-collar, but we also used it to bond it to the top of the stove, which is a squirrel.

 

The fit is good, so its a 3mm or so fillet, all way round, for about 40mm of height, so the 'exposed' portion is small. It has all lost its colour (not shame there then) and I have not checked it recently, but after a few firings it was still flexable.

 

Clearly its working at the top, if not slightly beyond, its design environment and if its smoking and swelling, thats not good, but for us its made a much better and much more durable seal than fire cement.

 

 

Daniel

[Ex- Member]

We use intumescent putty, Astroflame is a main supplier but there are different versions of it around like here http://www.canalshoponline.co.uk/contents/en-uk/d25.html

 

It creates a perfect seal around the upper chimney flu and is non setting so fully flexible. We also seal the flue into the stove with it. Never had any issue with this stuff. In tumescent putty is used in ships engine rooms to create fire brakes through cable entry ducting, it actually swells when under extreme heat.

 

Clearly temper range fits in with Quebec's figures. We have a back boiler so our stove will not reach anywhere near those temperatures.

 

1/2kg tub. Non-setting, weather resistant, non-flammable, stiff putty which allows small movements. Recommended for external and internal flue pipe joints. Can also be used for sealing service pipes and conduits through fire-rated walls, sealing the gap between a gas pipe and sleeve. Must not be used either where the pipe will be hotter than 250 °C (482 °F), or directly onto heating appliances.

 

9th product down

[madcat]

Interesting replies,thankyou. Probably will use the screw fix stuff because its easy to get. The whole thing has to come apart again when the new oven top appears anyway .

Hope to be boiling a kettle for tea fairly soon (madcat time)

[Ex- Member]

Interesting replies,thankyou. Probably will use the screw fix stuff because its easy to get. The whole thing has to come apart again when the new oven top appears anyway .

Hope to be boiling a kettle for tea fairly soon (madcat time)

 

If it has to come apart again why use a product that dries hard. Intumescent putty stays soft and is reusable.

[madcat]

It says must not be used where pipe gets above 250c or direct on heating surfaces so is no higher temp rated than the heat proof silicone offered by screw fix. My understanding is that the silicone doesn't set either. I have to gum up the smoke box to the top of stove joint,it's over the oven. The other place for it is where the flu goes through the collar,fire clay always falls out of there.

This doesn't mean I have dismissed the idea of intumescent putty, there will be a permanent job further down the line when the new oven top appears.

The crack in the old one has been fixed with some very old stock iron cement which has worked,I drilled a hole in the end of the crack first to stop it spreading.

[smileypete]

A similar question.

 

On the top out our stove I an not happy with the seal between the flange where the chimney connects and the stove top. Visually there is perhaps a 2mm gap part way round the flange. It is probably going to be quite hard to take it all apart and bed it on fire cement or high temp silicon, so I wondered what other suggestions there would be.

 

Working fire cement into the gap with a knife certainly seems possible, particularly the "softer" stuff above, but I was wondering it there is such a thing as thing are fireproof "string" that could be pushed into the gap before fire cement. Or any other suggestions?

 

There's fire rope or stove tape down to 2 or 3mm on Ebay (might help the OP), maybe pack with that and top off with cement.

 

Also make sure the flue to collar joint can take up any movement so there's no stress on the lower one, maybe use less tightly packed fire rope and heat proof silicone up there.

 

cheers, Pete.

~smpt~

[Ex- Member]

It says must not be used where pipe gets above 250c or direct on heating surfaces so is no higher temp rated than the heat proof silicone offered by screw fix. My understanding is that the silicone doesn't set either. I have to gum up the smoke box to the top of stove joint,it's over the oven. The other place for it is where the flu goes through the collar,fire clay always falls out of there.

This doesn't mean I have dismissed the idea of intumescent putty, there will be a permanent job further down the line when the new oven top appears.

The crack in the old one has been fixed with some very old stock iron cement which has worked,I drilled a hole in the end of the crack first to stop it spreading.

 

Sounds like a good repair. I wasn't sure if it's a wood burning stove as they burn hotter and might possibly go over 250c On stoves with back boilers though it works a treat. Never had any problems with cracking or leaks anywhere in all that time, not messy either much like Plasticine.

 

Hope the restoration goes well.

[Grace and Favour]

 

Sounds like a good repair. I wasn't sure if it's a wood burning stove as they burn hotter and might possibly go over 250c On stoves with back boilers though it works a treat. Never had any problems with cracking or leaks anywhere in all that time, not messy either much like Plasticine.

 

Hope the restoration goes well.

Just out of interest, I measured the stove top temperature of our Morso Squirrel this evening (we're all toasty and burning anthracite beans at the moment)

 

345^oC !

[Cambodan]

Hi All,

 

Does anyone know if the fire cement can be applied to the flue joint whilst is in use (hot)?

 

 

Thanks - Daniel

 

PS: As know one has looked at this post for a while, I'll wait a bit and perhaps put up a new post.

[pete.i]

I wouldn't use fire cement or anything that goes hard to be honest. I put fire cement on my Villager Puffin on the flue joint because what was on there had disintergrated. It lasted about six months because of the engine vibrations. I then used the high temperature silicon stuff and that was still good five years later. Problem is I could only find it in red or black.