Fireplace liner bottom termination

[Eric Williams]

Metal liner installed in masonry fireplace. Bottom termination of liner appears to be sealed in top of firebox (throat) with insulation. It is my understanding that bottom termination should be metal or other appropriate material. Any thoughts?

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[Nick Ostrowski]

Never saw that done before. That fireplace definitely needs a level II inspection. I don't see how that single wall liner (appears to be single walled) could possibly be rated for the temperatures generated in a wood burning fireplace. Looks like a hack job. Any signs of drafting issues?

[Eric Williams]

Never saw that done before. That fireplace definitely needs a level II inspection. I don't see how that single wall liner (appears to be single walled) could possibly be rated for the temperatures generated in a wood burning fireplace. Looks like a hack job. Any signs of drafting issues?

Nick,

There must have been some draft issues as there was a draft fan at the top termination of the chimney.

I'm not sure if the liner has to be double walled but I do know that it must be stainless steel and not aluminum for fireplace use.

[Lou Curley]

You don't need a double walled liner to reline a masonry fireplace, I'm not aware of a manufacturer that makes one. It does, however, have to be the proper alloy stainless steel. You can use foil faced ceramic wool for a bottom termination of some liners. This was taken from the installation instructions of the liner that I use:

"A second alternative is an insulation plug used to form a bottom plug
(Figure 14, Alternative B, page 18). It must be tightly packed with HomeSaver Foil-Face FlexWrap to a depth of 6". Refractory cement may be used
in between the layers of ceramic blanket to create the seal. Make sure there
is adequate support at the top of the chimney. If the liner, including insulation weighs more than 150 lbs., double up on top plates and top/bottom
support brackets."

The liner would require proper insulation to meet UL 1777, which may require a level 2 or 3 inspection to determine. Also, it looks like they downsized the flue opening when relining. Make sure to check that it's properly sized when doing the level 2 inspection.

Lou Curley
Drexel Hill, PA

[Bob Harper]

Good pick up on the liner size Lou and welcome to InspectionNews. Guys, Lou is a friend and good chimney sweep so be nice.

The bottom transition is stated in the listed instructions. The 1777 listing leaves this up to a mfr. as technically you don't have to list your liner for fireplaces--it could be intended just for heater flues. Some mfrs have been developing various hardware to make this transition such as a round ss collar with hardware cloth skirt that can be attached to the top of the smoke chamber with Tapcons then parged over for a smooth transition. The load is carried by the top plate. Again, UL 1777 requires a liner withstand a 200lb deadload when suspended from the top support plate except for aluminum liners for CAT I gas, which are only required to withstand a 100lb dead load. This means a lot of aluminum liners will be separating when stretched out for installation or come apart during the installation.

If they have an exhaust fan on top it is required by code to have an alarm interlocked that sounds during a power failure. If there are any other atmospherically vented combustion appliances in the home they should have combustion analysis along with a worst case depressurization test to ensure the fireplace doesn't backdraft them. Then install low level CO monitors in the home.