Looking for help, condensation running down chimney in new construction

[highmark18]

This is my first post here, so please bear with me. I have searched the forums, but cannot find a specific answer, so I am hoping some experts will chime in here, as I am not getting much help from my dealer.
I recently purchased a Heat N Glo RH36 Wood Burning Fireplace to install during new construction. It came with the double wall 10 1/2" chimney, and this is where the problem started. After installing it, I get water running down the chimney into the house when the temp is just right. To give a little background, the insert is in the basement, and then the chimney goes up through a chase into the attic, through the insulation shield (no chase in attic or on roof). When it gets cold (it was -15 here today), I get condensation on the warm side of the firestop at the attic. I also climbed into the attic and could not believe the frost just above the insulation line. Upon further inspection it looks like to me that frost forms on the inside of the insulation shield (they want 2" clearance between the shield and the pipe). Anyway, the frost forms, then melts when the temp is right and water runs down into the walls. I also get alot of ice buildup on the termination cap, and I feel that the warm air that is in between the double wall pipe goes up, melts the ice and the water runs down the inside of the outer wall, finds a seam to sneak through and then ends up on the top of the fireplace. I guess you could say this is a 2 part problem.
Anyway, my local dealer is not much help, and I am hoping I can find somewhat of an answer before I decide to just rip it out. It is really putting a damper in my new construction. I was told that building a chase around the whole chimney would help, but wouldn't the cold air still get in the outer wall of the chimney through the top?
Any help or suggestions is GREATLY appreciated.

 

[Pagey]

Just reading your description, I'm not sure how similar your setup is to mine, but I recently had a leak running down the side of my Class A stainless steel chimney. From there it would collect in the ceiling support box and then drip onto the stove. After closer inspection, the water appeared to be running down one of the vertical seams on a section of the Class A. The installers came back on Saturday morning and did some additional caulking. The leak has, so far, not returned. I'm skeptical until we get another hard, driving rain, though. Maybe this will give you an idea of which direction to go...?

 

[highmark18]

Thank you for the reply. Regarding the caulking, I have gone and caulked all the joints, and it only re-routes the water. It is definitely a condensation problem, as it is at or below zero here now for the past few days. I have got a large amount of frost/ice at the termination cap, and am not even using the fireplace. I am afraid to try it again, knowing the heat from the smoke will melt the ice/frost, and down the water will come again.

 

[RocketMan]

Sorry to hear about your problem! I know that many fireplace manufacturers do not recommend air-cooled chimneys in cold climates because of condensation issues.

A couple of questions:

Is the cold air ducting for the chimney being drawn from outside air (much drier, especially in cold weather)?

Are the walls sealed around your fireplace/chimney in your heated envelope area?

 

[highmark18]

No, the air drawn into the chimney is from the basement, which I think is part of the problem.
Yes, the walls are sealed up in the house, but there is no chase beyond the ceiling.

 

[oconnor]

If you can draw air from outside the house, that would be better - The condensation that is forming on the chimney will also form on anything else cold in the attic - BAD.

I have no experience with air cooled chimneys, but I do know that a damp attic isn't good, and venting warm household air into the attic is a waste of heat.

 

[jtp10181]

You should add a chimney air kit into the pipe and duct it outside, this will seal off the outer pipe wall from the inside house air. Also building a fake chase around the pipe in the attic might help as well. This could be done with that stiff insulation board with foil backing on one side. Tape the edges with foil tape to make it air tight. Make sure the 2" clearance around the pipe is maintained. Also one thing the dealer might have missed is caulking the fire-stop where the pipe penetrates the attic. We just recently (earlier this year) got approval from UL to caulk the fire-stop going into the attic on the SL300 pipe. This will stop a lot of the humid house air from blowing into the attic right up against the ice cold pipe.

 

[73blazer]

That fireplace uses the double wall SL300 pipe. I second the Chimney Air Kit. Hearth&Home;is weird, some of their fireplaces say they are required, and others don't. Others say Required in Canada. I just downloaded the manual for yours and it only says it's required in Canada but recommended on all. My North Star fireplace said it was required on all installations. I'm a firm believer that all SL300 installations should have the Chimney Air Kit.

It's easy to install IF you still have access to get to the flue connection on the top of the fireplace. The kit just encases the bottom portion, and you run a duct to outside. The proper kit for your fireplace is the CAK4A. Note this is different than the Outside Air Kit, that kit provides combustion air from outside to your fire.

 

[highmark18]

OK, thanks alot guys. I was wondering about that chimney chimney air kit as well. The only thing I wonder is that since you are now running outside air through the outer wall of the chimney, won't you get condenation on the chimney itself due to it being exposed to the warm air in the chase?
I am also still confused as how to avoid the condensation problem where the chimney goes through into the attic, as the insulation shield gets major frost on the inside of it, and causes condensation on the warm side of the fire stop. I have attached a pic.
Just talked to my dealer, he swears that if I build a chase all the way through to the peak, that this problem will go away. But won't cold air still penetrate the chase down to the firestop?

 

[73blazer]

I have a fully insulated chase on an outside wall running 28' up from my fireplace with the SL300 pipe. I do not see any condensation on it. But it hasn't gotton down that low yet, I think 8 degrees is the coldest it's gotten here thus far. I have 2 firestops, I never popped the first one either to see if condensation is forming on the upper one, but I think if it did, it would drip down, the top of my fireplace and underside of my first firestop is bone bone dry. I've checked it several times, during the course of operation, while it's no operating, and when I fire it up from cold, which is probably the scenario which has the best chance of making condensation.
I'm not a fan of air cooled chimneys in very cold climates, I had asked Hearth&Home;if I could use the Simpson Duraplus pipe on my fireplace, you can on the quad 7100, the simpson base plate is even listed in my manual, but they said no, only the SL300 pipe. I know, that doesn't make you feel any better.
There was some other post on condensation issues with this pipe IIRC, a Canadian installer posted a response saying he installs them alot and doesn't see condensation issues.
How high is your chimney?
I'd try to keep as much cold air away that pipe as is possible thru whatever means. Warm air condenses when it becomes cold. Cold air becoming warm does not condense. Insulate the pipe (without touching it, always maintain your 2" to combustibles from the pipe), build an insulated attic chase around it, whatever you have to do, and keep cold air from getting to the outside of that pipe. The chimney air kit will help bridge the temp gap between the inner and outer walls, and no condensation is supposed to form. That's the theory anyway.
Has your dealer taken a look at it? Won't he help at all?

 

[highmark18]

Dealer won't come and look at it, I guess 60 miles is too far to drive to keep customers happy.
The more research I do and questions I ask, I agree with you, building a chase all the way up is going to be my best bet. Should I build it above the roof as well, all the way to the termination cap? Pipe is approx 4' above the roof.