approx temp of liner 12" up from insert?

[kitand]

I'm installing some foil-faced roxul board in my hearth near my insert. It will NOT be touching the insert, but WILL be touching the flex chimney liner about 1 foot above the insert (standard liner with the corrugated outside). I want to make sure whether my foil tape can attach well (temperature-rating-wise) to the 6" flex liner at that point. Approx how hot, max, does the liner get one foot up in standard use, in anyone's experience? My liner exits the back of the insert at about a 45-deg angle. The model is Vogelzang TR004, Btu 69K. I've got it all disconnected right now for the insulation work, so it's kind of cumbersome to fire it up and test it myself! Thanks for any ideas.

 

[begreen]

Keep the tape away from the liner. It's probably not rated for the potential temps. Depending on how the stove is run the liner surface may be in the 300-500º range that close to the insert. But it could go up much higher. Make the hole the size of insulation jacket of the liner and continue the liner + insulation through the hole, compressing the insulation a little to get it started.

How is the roxul board going to be secured in place?

 

[bholler]

The tape wont hold up in contact with the liner. It wont hurt anything but wont help either. It hold up ok on the outside of half inch insulation wrap but looses its adhesive quickly where it is in contact with the liner.

 

[kitand]

Thanks begreen and bholler.
I was intending the tape partly just for energy efficiency and partly to help suspend the roxul board in case of sag. Sounds like the suspension wouldn't be practical anyway, if adhesion is lost with high temp. There is foil tape rated 600F, so that might be a possibility, at least for energy efficiency. There is not much gap of the roxul board insulation around the liner, so I'll probably just skip the tape there and fit a collar around it for looks.

The roxul board is for creating better convection and radiant from the area around the insert. But as I've been installing it, it seems the top horizontal roxul sheet maintains its shape and suspension fairly well when taped onto vertical roxul sheets at back and sides of hearth. Basically I'm lining the walls and top of the hearth area, the top at a bit of an angle to increase convection to room. If the roxul board sags with time, I plan to reinforce its shape with some galv "hardware cloth".