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Benjamin
Re: Fireplace Pipe Dripping
Benjamin
Molly4 wrote:

The pipe the insulation is wrapped around does not get any heat from the flex pipe from the fireplace. There is a good 3 inches of clearance so I doubt it is a fire hazard.
If you are asking about the flex pipe it runs up through the middle of the old rigid pipe. I am not sure what you mean by the flex vent. It seems that when the temperature gets in the 20's is when the dripping happens. Snow or rain on the roof does not make it drip. So there has to be a condensation issue somewhere along the line. No idea how to figure out where.
And the idea that it might take 2 years to resolve makes me want to move!

It is not allowed that pipe has a clearance to combustibles requirement that needs to be met. No exceptions at all.

Megan
Re: Fireplace Pipe Dripping
Megan

Holler2 did you look a the pictures? The actual pipe from the fireplace is not in contact with the non-combustible insulation.

ed21
Re: Fireplace Pipe Dripping
ed21

Do you close the damper when he fireplace isn't in use. Warm humid air could be escaping up the flue and condensing when it gets to the colder pipe. Depending on the type of flue, it may be possible to insulate it as it passes through the attic. As mentioned this could be a fire hazard or not allowed by code.
Checking the roof cap is a good place to start, although since rain doesn't seem to cause it, maybe not.
I have to admit I didn't know flex pipe was used for wood burning fireplace flues. I've only ever seen double wall or b vent. Gas is probably different.

Megan
Re: Fireplace Pipe Dripping
Megan

This isn't a wood burning fireplace it is gas. The flex pipe just runs up through the old wood burning pipe to the roof. But now I am wondering if the enormous amount of space between the flex pipe and regular pipe from the house is causing the condensation. But even if it were how would it be repaired?

ed21
Re: Fireplace Pipe Dripping
ed21

The question for me is the condensation occurring in the pipe or on the outside of the flue. As I recall dampers on some gas fireplaces can't be closed completely to prevent air from going up.
Sealing around the metal flue and the old flue would keep air from traveling up the flue. Doing the same thing at the cap above the roof could help too.
Of course these are ramblings from someone who doesn't install gas fireplaces and doesn't know that much about them. You might ask the installer about the wisdom of any modifications. It seems to me condensation is the reason for the dripping unless water is somehow pooling and dripping over time.

Benjamin
Re: Fireplace Pipe Dripping
Benjamin
Molly4 wrote:

Holler2 did you look a the pictures? The actual pipe from the fireplace is not in contact with the non-combustible insulation.

Yes i did see them and yes that insulation that is combustible is touching the fireplace chimney. no matter what you have in that zero clearance box you need to maintain proper clearances to combustibles. Is your zeroclearance fireplace even rated for an insert (most are not) Now as far as the condensation goes is the damper opening sealed off around the small gas liner? Is the gas liner insulated?

Megan
Re: Fireplace Pipe Dripping
Megan

We will remove the insulation. It doesn't seem to be helping anyways. I am not sure what a zero clearance fireplace is so I can't tell you if it is rated for an insert. There is no damper opening around the small gas liner and I am willing to bet the flex pipe is not insulated. Thanks again for taking the time to help sort this out!

Benjamin
Re: Fireplace Pipe Dripping
Benjamin
Molly4 wrote:

We will remove the insulation. It doesn't seem to be helping anyways. I am not sure what a zero clearance fireplace is so I can't tell you if it is rated for an insert. There is no damper opening around the small gas liner and I am willing to bet the flex pipe is not insulated. Thanks again for taking the time to help sort this out!

what you have is called a zeroclearance fireplace it is a metal box with cooling air channels and a metal chimney attached to the top. Most of them do not allow an insert to be installed in them. But if you do put on in them you still need to adhere to all clearances and not obstruct the air vents around that box at all so it can still cool properly. What i am talking about when i say the damper opening is the opening that the smoke used to exit that box when it was a wood burning fireplace now it has a small pipe running through it and space around that. That space allows air from the house into that pipe and you will get condensation which is made worse by the pipe being uninsulated. at the least there should be noncombustible insulation like mineral wool or ceramic wool stuffed in there to stop the air flow. A sheet metal plate would be better with the insulation above it.

Megan
Re: Fireplace Pipe Dripping
Megan

I think there might be some confusion. The old wood burning fireplace box was completely removed and the pipe attached to it as well. The gas fireplace that was installed is free standing. As for the appropriate clearances I would hope the company that installed the fireplace adhered to those. There is no "damper" opening just the old outer pipe that is not insulated that goes all the way to the roof. But I think you are absolutely right about the condensation being caused by the open space around the flex pipe. And just so I am clear I should be able to fill the open space between the rigid and flexible pipe with mineral wool or ceramic wool? Thanks so much for your help.

Benjamin
Re: Fireplace Pipe Dripping
Benjamin
Molly4 wrote:

I think there might be some confusion. The old wood burning fireplace box was completely removed and the pipe attached to it as well. The gas fireplace that was installed is free standing. As for the appropriate clearances I would hope the company that installed the fireplace adhered to those. There is no "damper" opening just the old outer pipe that is not insulated that goes all the way to the roof. But I think you are absolutely right about the condensation being caused by the open space around the flex pipe. And just so I am clear I should be able to fill the open space between the rigid and flexible pipe with mineral wool or ceramic wool? Thanks so much for your help.

Ahhhh ok that is totally different. Sorry for the misunderstanding. I do have one concern you say they used flexible pipe. is that flexible pipe in the old chimney the entire way or is any of it exposed? I only ask because that is a liner that is only meant to go into an existing chimney. As long as that pipe is not exposed and if it is it honors any clearances to combustibles listed in the manual for your fireplace you are fine and i think stuffing the open space wit hnon combustible insulation will take care of the issue.

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