Can I insulate double walled stove pipe?

[ksp]

I have two tube heaters in my shop which is heated but they vent through an insulated wall and up through the roof in an uninsulated part of the shop. The pipes really condensate and drip water in the unheated area. My question is can I insulate the double walled vent pipe and if so, what should I use? Any recomendations?

 

[Weldman]

Ceramic insulation commonly found for ovens, kilns, and forges. Maybe more but be sure it can take at least 2k degrees.

 

[kaymccampbell]

You could wrap it in rock wool. It's rated to 2000°. I'd feel safe doing that.

 

[jack stand]

You said double wall, ever shoot the temperature with a little i/r thermometer? Open-faced f/g might be ok depending on the temperatures. As I understand it f/g technically doesn't burn but the facing and possibly any "binder" might brown or off gas with enough heat. ??
Rockwood is the best, but how would you fasten it. It's quite heavy compared to f/g that also would need to be fastened as well, just not as heavy.
I've thought about this in another application and chicken wire or some light hardware cloth is all I come up with to keep it in place but would seemingly require about 6 hands to do it. (and I have not, yet)

 

[kaymccampbell]

Keeping in place is easy. Cut a square of rockwool. Cut a hole in the square the size of the double wall. Cut a slot from the hole to the edge of the rockwool square. Pop the giant rockwool bread bag clip over the pipe, alternating the slots. Do it till you cover the pipe and Bob's your uncle, insulated vent.

 

[gmcgeo]

There are many companies that make high temp insulation, made for just this situation. They make them for any size of pipe, and sell them in different lengths.

I recommend finding out the specs of what you have, and check with the manufacture to make sure its up to their code before do it.

 

[danski0224]

Pretty sure that insulating it isn't allowed.

Need to check with manufacturer.

 

[Yankeefarmer]

During heating season, the double wall pipe should be above the unheated space temperature, thus condensation on the outside shouldn’t be occurring. If the condensation is occurring on the inside, it should be staying inside and running back to the combustion zone. Does the condensation occur during the summer, due to cooled air escaping through the vent? Or is your vent leaking through the joints?

 

[ksp]

Thanks for all the replies and advice. The double vent goes through my wall into the unheated area and then turns up through the roof. The condensation runs down the pipe and drips on my floor making ice bergs on my floor. But I wonder even if I insulate the pipe to where it exits the roof I may still have condensation and thus never cure the dripping problem.

 

[PoorUB]

How much ice are you dealing with? Perhaps just hang a bucket to catch the drips if it is not an excessive amount.

The B-vent on may shop heater drips right on the side of my pickup. I never noticed until one day I washed it and the paint was streaked on the passenger door. Now there is a 5 quart ice cream pail hanging off the B-vent to catch the drips. It has been like that for 5-6 years. It never fills up, as it doesn't drip that much so it evaporates off.

 

[metlmunchr]

Unless the code has changed in the last few years, you can't insulate B vent because part of the design of the pipe is one inch of free air space around the outside.