Sealing a flue?

[pauljygrant]

Hi,
I am part way through installing a wood burner with triple wall flue. The flue has crimped ends that fit together but I would prefer to seal the joints. A local plumber said that he uses Bostik Roof & Gutter Silicone. The data sheet for the product gives a temp range up to 177 degrees C. Does anyone know how hot the active flue will become and whether they have used any product to seal the crimped connections?
Any help appreciated.
Thanks, Paul

[dan76]

you could try giving these people a ring, they talk about using silicone to seal the ovens


http://clayworkswoodfiredovens.com.au/kit.htm

[China]

Silcon of the propper grade will be fine, I would be very supprised if your flue reached, 177 deg c

[wonderplumb]

Id be inclined to use the fire rated silicone sealant, it comes in a standard sized tube and is available from bunnings etc. or Reece, tradelink etc.

[Uncle Bob]

I've seen flues glow red, so it would have to be some space age silicon.

Roof and gutter silicon *might* be ok on the liner. I would never use it on the flue and I've actually never used any sealer on a flue (the way they're made seals the joins).

[woodcutta]

Don't use any sealer at all. I installed our wood burning fire 3 years ago and had the same concern.

I contacted the supplier and asked what to seal it with, and their answer was dont seal it - so I didnt and it had never leaked smoke into the house.

Regards
woodcutta

[Smurf]

No need to seal it and it would be safest not to unless you're absolutely sure whatever you seal it with won't burn (and worse still, burn and melt / drip burning goo at the same time).

The flue should seal fine the way it's made. In the unlikely event that you do end up with a small leak, under normal circumstances the effect will be to suck air in to the flue rather than let smoke out.

This is because of the natural convection effect of the hot gases in the flue - it's what makes the heater work the way it does and everything has been designed with this in mind (assuming it's a reasonable quality heater).

The one seal that you do need to worry about is the one around the door of the heater. After a few years it will need to be replaced. It's not expensive, only a fibreglass rope worth a few $, but if not replaced it will let in too much air and this will over heat the firebox causing damage to the heater. You'll know when it needs replacing as the door won't have a nice, tight fit when closed but will seem loose.

[Brickie]

The crimps (spigot) face down the flue and sit in the open end (socket) this allows the fire juices to run down the flue to be burnt again.