Hi all, I'm new to posting on the site. I am considering installing a Harman P52i insert in my 42" FMI ZC prefab fireplace. My question is about the venting. I want to remove the current double wall 8" chimney except the section penetrating the roof and run new PL 4" pipe fromt he unit out the 8" chiminey with a rain cap. do to the fact the exhause pipe on the Harman is not in the center and is on the right side, can i cut a hole in the top of the ZC unit and run the PL straight up instead of turning and running out the 8" flue in the zc unit. My thought is to cover the 8" flue with metal from inside the zc unit and also on the outside. I would also run the OAK the same way by cutting a hole in the top of the zc unit and go straight up and then horizontal out the side of the house. I would also attach a firestop plate to the top of the zc unit where the new 4" pipe is exiting it. I have good access to the top of the zc unit through my chimney chase through my attic so that is a no issue. It seams this would be the way the pipes would run anyway if using the Harman zc box. thanks for any advise given.
Venting pellet insert through prefab zc fireplace
- Thread starter brtem
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Lake Girl
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CaptSpiff
Minister of Fire
Both organizations would not likely be happy to hear that you are cutting the metal top of the zero clearance FP. Not because it could not be done safely, but rather because the P52i instructions probably warn against that type of modification. Especially since you are not using the old Class A double wall as an uninterrupted chase to the top.
If you choose to proceed with this method (sounds like you've given it significant thought) then your safest route is to use pipe rather than flex. You mention pipe and I wanted to be sure you meant PIPE. Also consider wrapping the pipe in 1/2 inch insulation usually used on flex. Not cheap, but extra insurance. Connection to the 8 inch could be a problem as each manufacturer fittings are different, or are you just using the "roof penetration" as an 8 inch chase for the 4 inch pipe?
Lastly, the exhaust vent to pipe connection inside the zc-fp will be tricky because it will have no flex. How will you disconnect it for annual P52i removal to clean?
I guess my thought on this is if someone was installing in a prefab unit and used the current metal flue with a SS flex liner. And also wanted to install the OAK how is the OAK pipe routed out of the prefab fire box without cutting a hole in the top?
Yes I am using 4" double wall PL pipe not flex. Insulation wrap should only be needed inside the firebox area, rest of run will have 6-8" clearances to combustbles.
I would only be using the 8" as a chase where it penetrates the roof to avoid roof repairs for the smaller pipe.
I most likely will do a tear out of old prefab and use the zc box from Harman but was trying to save some money.
Also chimney pipe or flex pipe mounts permanent to frame for the P52i the unit pulls out of the frame for cleaning, it had a silicone gasket that mates up to the frame flue when pushed back in place. Thanks
Yes I am using 4" double wall PL pipe not flex. Insulation wrap should only be needed inside the firebox area, rest of run will have 6-8" clearances to combustbles.
I would only be using the 8" as a chase where it penetrates the roof to avoid roof repairs for the smaller pipe.
I most likely will do a tear out of old prefab and use the zc box from Harman but was trying to save some money.
Also chimney pipe or flex pipe mounts permanent to frame for the P52i the unit pulls out of the frame for cleaning, it had a silicone gasket that mates up to the frame flue when pushed back in place. Thanks
CaptSpiff
Minister of Fire
It sounds like you've done your research on the P52i. I do not know this model that well.
I am very familar with a Quadrafire Santa Fe insert which was installed nearly identical to your intentions. In that case the back and most of the upper case of the existing ZC FP was cut away via sawzall. Also the metal floor of the ZC FP was covered with 5/8 inch cement board over a thin set of fire brick morter.
The local inspector initially rejected the proposed design because of the removal of part of the ZC FP outer shell. He became reluctantly convinced only when we reviewed the Quad SF insert installation manual, which specifically allows the Quad SF insert to be used as a DIRECT BUILT-IN. The install manual has "min clearance to combustabiles" for both standard insert installs (Masonary & ZC) and a wood frame built-in install. We made sure all side/back/top minimums were documented and he signed it off.
We did have to fabricate a 15" flex which we labeled "appliance adaptor", and we did wrap it in 1/2 insulation as though it was class A. We could not get a good gasket seating without it. This little mod almost doubled the price of the vent run.
Good luck with your install and inspection.
I am very familar with a Quadrafire Santa Fe insert which was installed nearly identical to your intentions. In that case the back and most of the upper case of the existing ZC FP was cut away via sawzall. Also the metal floor of the ZC FP was covered with 5/8 inch cement board over a thin set of fire brick morter.
The local inspector initially rejected the proposed design because of the removal of part of the ZC FP outer shell. He became reluctantly convinced only when we reviewed the Quad SF insert installation manual, which specifically allows the Quad SF insert to be used as a DIRECT BUILT-IN. The install manual has "min clearance to combustabiles" for both standard insert installs (Masonary & ZC) and a wood frame built-in install. We made sure all side/back/top minimums were documented and he signed it off.
We did have to fabricate a 15" flex which we labeled "appliance adaptor", and we did wrap it in 1/2 insulation as though it was class A. We could not get a good gasket seating without it. This little mod almost doubled the price of the vent run.
Good luck with your install and inspection.
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