Chimney flue condition

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MRD1985

Feeling the Heat
Nov 19, 2023
372
02888
As some of you know my fireplace chimney had some issues so instead of rebuilding the masonry chimney I opted to install an insert with insulated liner in that flue. I was up on the room taking some measurements prior to liner install and happened to check out my boiler/water heater flue that is gas fired for the last 10 years, was previously oil. Condition is questionable. Would you continue to operate this flue in this condition? There are gaps in a couple of spots between the terracottas and what appears to be concrete terracotta. In the photo it also appears there is a hole pretty far down the flue. Here are some photos. The hole appears to be right in the middle of the photos (difficult to capture clearly). What say the experts here?

A liner install would not be easy. I would have to break apart the chimney by the boiler to install a custom/specialized T pipe to connect the water heater and boiler (would that be even feasible without compromising the structural integrity of the chimney in that side?) Pictures below.

Edit: found this chunk in the clean out in the basement. There appears to be 2 holes. One has brick chunks showing and the other just with this piece missing out of it..


Now the question is, how to proceed ? I have no choice but to continue to use my water heater. But I can live without the boiler. I have the stove and a cold climate heat pump.

Mods if this isn’t correct sub forum please move to appropriate area thank you
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As some of you know my fireplace chimney had some issues so instead of rebuilding the masonry chimney I opted to install an insert with insulated liner in that flue. I was up on the room taking some measurements prior to liner install and happened to check out my boiler/water heater flue that is gas fired for the last 10 years, was previously oil. Condition is questionable. Would you continue to operate this flue in this condition? There are gaps in a couple of spots between the terracottas and what appears to be concrete terracotta. In the photo it also appears there is a hole pretty far down the flue. Here are some photos. The hole appears to be right in the middle of the photos (difficult to capture clearly). What say the experts here?

A liner install would not be easy. I would have to break apart the chimney by the boiler to install a custom/specialized T pipe to connect the water heater and boiler (would that be even feasible without compromising the structural integrity of the chimney in that side?) Pictures below.

Edit: found this chunk in the clean out in the basement. There appears to be 2 holes. One has brick chunks showing and the other just with this piece missing out of it..


Now the question is, how to proceed ? I have no choice but to continue to use my water heater. But I can live without the boiler. I have the stove and a cold climate heat pump.

Mods if this isn’t correct sub forum please move to appropriate area thank you
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Yeah you need a liner pretty badly but you can use it until you get one installed. And no you don't need a custom tee. Just 2 tees right ontop of each other. But getting a 6" liner in there is going to be fun. I would run the numbers and see if you could downsize to 5 or 5.5
 
Yeah you need a liner pretty badly but you can use it until you get one installed. And no you don't need a custom tee. Just 2 tees right ontop of each other. But getting a 6" liner in there is going to be fun. I would run the numbers and see if you could downsize to 5 or 5.5
Boiler exhaust is 7”. Water heater is 4”. Flue is 9x13. I’d need a 7” liner with a 4” and 7” tee. Not sure if it should be downsized with 2 appliances in that flue. I think it would be difficult to get a 7” liner down that. It also drafts very well on the 7”. i feel like on the 6” it would be even worse, almost pulling too much.

To be clear, what is the level of urgency to get a liner installed? I know my wife will want a cut and dry answer from me when I tel her this flue has had it too. I’m assuming we shouldn’t go the rest of the heating season using this? Isn’t there a risk of CO entering the house through the chimney flue and creeping through any small gaps in the motar?

Is there an issue opening up that chimney at the base like that say an 12”-18”x 2-3 ft hole without causing any structural issues?

I’m half tempted just to run a 4” liner for the water heater, and turn the boiler off and if needed eventually switch to a direct vent condensing boiler. 🤔. Id just have to use the stove and supplement with the heat pump if needed
 
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Boiler exhaust is 7”. Water heater is 4”. Flue is 9x13. I’d need a 7” liner with a 4” and 7” tee. Not sure if it should be downsized with 2 appliances in that flue. I think it would be difficult to get a 7” liner down that. It also drafts very well on the 7”. i feel like on the 6” it would be even worse, almost pulling too much.

To be clear, what is the level of urgency to get a liner installed? I know my wife will want a cut and dry answer from me when I tel her this flue has had it too. I’m assuming we shouldn’t go the rest of the heating season using this? Isn’t there a risk of CO entering the house through the chimney flue and creeping through any small gaps in the motar?

Is there an issue opening up that chimney at the base like that say an 12”-18”x 2-3 ft hole without causing any structural issues?

I’m half tempted just to run a 4” liner for the water heater, and turn the boiler off and if needed eventually switch to a direct vent condensing boiler. 🤔. Id just have to use the stove and supplement with the heat pump if needed
Oh if it's 7 you might get down to 6 depending on the numbers but probably not which means clay removal or oval. And you can still just run 2 tees or join the pipes outside the chimney and run one tee.
 
Oh if it's 7 you might get down to 6 depending on the numbers but probably not which means clay removal or oval. And you can still just run 2 tees or join the pipes outside the chimney and run one tee.

If I don’t do the clay break out myself, I’d assume this would be in the neighborhood of a 3000-5000$ job? Chimney is about 20 ft maybe slightly more.

Is opening up that side of the chimney that much to do the repairs going to cause any structural issues ?

Also, what level of urgency is this in your opinion? I assume not going the heating season like this?
 
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If I don’t do the clay break out myself, I’d assume this would be in the neighborhood of a 3000-5000$ job? Chimney is about 20 ft maybe slightly more.

Is opening up that side of the chimney that much to do the repairs going to cause any structural issues ?

Also, what level of urgency is this in your opinion? I assume not going the heating season like this?
Opening it up isn't a big deal normally but I really don't think you will need to. I would say you could finish out the season and get it done over the summer
 
The flue my oil boiler was on is in much worse shape when I took it out of use. I need to break out the tiles on mine and line it for a wood stove. It’s sitting unused at the moment.

My boiler was far from young, so I put a wall mount up to free up floor space and poked through my sill plate for intake and exhaust.
 
The flue my oil boiler was on is in much worse shape when I took it out of use. I need to break out the tiles on mine and line it for a wood stove. It’s sitting unused at the moment.

My boiler was far from young, so I put a wall mount up to free up floor space and poked through my sill plate for intake and exhaust.

I’m half tempted to do that and just run a small liner for the water heater and not use the boiler. I don’t think I really NEED the boiler any more with the stove and the heat pump. So it’s hard to justify the cost of a 2000-2500$ liner and a fair amount of work to get it to work.

The pictures don’t do it justice but there is at least a 4-6” hole in one spot and then a big chunk missing with broken bricks coming through the broken terracotta in another spot. And then gaps between the tiles toward the top. I’m surprised it has been said continued use is suitable in this condition? Wouldn’t these large voids allow carbon monoxide into the air space between the chimney and flue and possibly get into the house ?
 
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Opening it up isn't a big deal normally but I really don't think you will need to. I would say you could finish out the season and get it done over the summer
Full ovalized 7” kit will probably run me 2500$ my cost when I tally up everything. Plus brick and mortar. 4” round liner is only around 500$ for the water heater 🤔