Questions about stove and sizing of pipe

[deene]

we bought a house recently that has a wood stove plumbed into a purpose built chimney. the flue tile has a crack so im going to have to do something different, suggestions have been to put a liner in it, or tear it down and install a dbl wall stainless flue pipe. we want to maintain the look of the chimney on the roof because its rock and matches the rock on the face of the house. Question one is the stove has an 8 inch outlet, does it need to be that size, its to big for the house as it is and will run us out if used to capacity, so will just be used for pwr outages and for weekend low fire comforts. can i reduce to 6 in which would be easier to reline flue with pipe of that size (round pipe in a square tile), or do i need to leave it at 8 and tear it all down and start over? thanks for the help and advice.

 

[rustred]

If the stove requires 8 inch pipe I dont think I would reduce it to 6 inch. Maybe 7 inch. Whats easier going with a 6 inch chimney and replacing the stove to match. Or redoing the complete chimney. As u say its more of a fill in thing. Few things to try. Plus dont get a roaring fire going in it if youre going 6 inch. Its sn experimental thing. Dont tell your insurance if u have insurance as they wont pass that. And if It burns down your ins. Wont be valid anyhow. They will want it done properly.

 

[37 chief]

When I installed my antique wood stove the opening for the stove pipe was 7 inch. I reduced it down to 6 inch. My pipe goes horizontal for 3 ft then up probably 15 ft. I haven't had a bit of trouble. I would think you could use a 6 inch pipe. You might want to get a better opinion. Stan

 

[Stan Coryell]

With a fire I wouldn't chance it. Can you get the instalation manual for your stove? This would have the flue sizing requirements.

 

[mjsnodgrass]

i had a chimney fire in a nearly new chimney. local fireplace store installed a liner. it was simply a thin stainless tube. it was about 30 ft long. it was under 1k installed, but it was also 20 yrs ago. been trouble free up to the time i sold the house. good luck

 

[Paul swpa]

deene, my best guess from here would be to stay with the 8 flue liner.If it is a name brand stove you should be able to find some documentation online from the manufacturer for recommendations of flue size. We had to have that done several years ago after a major flue fire. Also I would consider where and how big of crack(s) are in the existing flue tile. They all will get hairline cracks at the top from temperature changes and I wouldn't worry about those too much, if the cracks a pretty good (like pieces are loose or nearly loose) and anywhere other than the top few inches, then I would think about doing something. The chimney construction also plays a part in that. Ours is way overbuilt with fire brick and stone and the outside faces stayed cool even though the stove got hot enough to bubble the ceramic glass in the doors! Paul

 

[ss55]

Six inch pipe would be about 0.56 of the area of an eight inch pipe. I would get a few estimates for the job.

 

[redforlife]

I wouldn't go against requirements of the stove. Reducing pipe size, would likely be doing that.

I'd also check with your homeowners insurance. You don't want to spend money on an installation that your insurance won't allow. And they will excempt it, or not be liable for a chimney they don't allow. It's your home to do as you please, but what they are willing to cover on the insurance is a different story. If they require triple wall pipe, then that's what they require for coverage. And so on.

 

[Traditional Farmer]

I have a Fisher Papa Bear with a 6 pipe been burning it hard since I bought it in 1977 can't imagine a stove would need a bigger pipe.

 

[BarnyardEngineering]

It's just money, right guys?

Reality is, physics. The stove won't flow more air than the chimney will draw. It may burn like a smaller stove, or it may not be affected at all if the draw is good enough.

 

[Fixingfarmer]

Liner. I would love to have a chimney instead of my stove pipe. Often the new codes will want double wall inside then triple going through the wall you would be surprised how much those stainless sections cost vs the double wall especially if you want it all to look the same and keep running the triple up the wall to above the roofline. It was like 2400 in stovepipe would go a long way even if you have to rebuild the chimney at least its money better spent. I think repairing the existing stuff wouldnt cause any more draft problems than exist at the moment if it worked well before

 

[Tim in New York]

I worked in a stove store back in the 80's. I would say you need to stay with the 8 flue. The stove outlet is designed for the size of the firebox and the size of the door. Go smaller and you will have problems with smoke in the room when you open the door. As far as smoke and gases exiting the chimney, there are a lot of variables - height mainly, temperature outside, barometric pressure, etc. If the stove is too big to begin with, you will be running it low and more likely to build creosote and have problems.

Back then the new innovation for relining fireplaces was to break out all the old tile, insert an inflatable balloon in the chimney, and pour a special concrete mix around the balloon. That mix was supposed to fill any voids in the chimney blocks or stone and insulate the flue. Was pricey back then. I supposed there must be improved versions of that still around.

Tim

 

[Hemmjo]

Might be cheaper to buy a new smaller modern wood burner. The new ones burn cleaner, have smaller flue, some have catalytic converters. I have a 35 year old Defiant Encore that works very well when we use it. But it makes too much heat, so we should have gotten a smaller one.

 

[Russ from MN]

Most newer high efficient stoves have a 6 outlet, and they work fine with a 6 liner. I think they work better with a liner than the clay flue because the liner will stay hotter. Our son had a Lopi high efficient insert stove installed in conventional fireplace, and it worked great.

 

[Russ from MN]

Most newer high efficient stoves have a 6 outlet, and they work fine with a 6 liner. I think they work better with a liner than the clay flue because the liner will stay hotter. Our son had a Lopi high efficient insert stove installed in conventional fireplace, with a 6 liner, and it worked great.

 

[PJH]

Redforlife mentioned step #1 - check with your insurance agent.

I made changes in this old house chimney at their insistence. About two years later they moved the goalpost and demanded a new triple wall chimney. Then a few years later they said that they wouldn't insure the house unless I completely removed the wood furnace. That was 25 years ago. We got an outside boiler. That was the end of the dictates. I should have put the outside boiler in on the gitgo and saved the cost/work of complying with their evolving ideas.

 

[Russ from MN]

Outside boilers are fine if you like to cut a lot of wood! Our friends bought one of the new highly efficient ones, and it has been nothing but a headache!

 

[marloweg]

keep the 8 inch or you will have a house full of smoke not enough draft

 

[PJH]

Russ, I recently hauled 14 1-ton loads of wood up to the boiler. Yeah, it takes a lot of wood, but the entire house is underwear comfortable on the coldest day. We can usually get through our Southern Illinois winters with 14 - 16 loads of wood. I have a few more loads waiting to haul in if needed. We have heated our house and our domestic hot water with this Hardy boiler for 25 nearly trouble-free years. I have always said that I would buy another Hardy boiler if this one failed, but I am approaching age 75. I'm now gearing towards baseboard electric heat for the day that I flop over dead in my tracks. My widow can twist a thermostat to keep herself warm. The money that we have saved with the Hardy will keep her warm for the rest of her days. She has happily helped me cut, split and load several hundred loads of wood in the last 50 years. She has earned a rest.

 

[atlarge54]

(quoted from post at 05:16:06 10/31/23) Russ, I recently hauled 14 1-ton loads of wood up to the boiler. Yeah, it takes a lot of wood, but the entire house is underwear comfortable on the coldest day. We can usually get through our Southern Illinois winters with 14 - 16 loads of wood. I have a few more loads waiting to haul in if needed. We have heated our house and our domestic hot water with this Hardy boiler for 25 nearly trouble-free years. I have always said that I would buy another Hardy boiler if this one failed, but I am approaching age 75. I'm now gearing towards baseboard electric heat for the day that I flop over dead in my tracks. My widow can twist a thermostat to keep herself warm. The money that we have saved with the Hardy will keep her warm for the rest of her days. She has happily helped me cut, split and load several hundred loads of wood in the last 50 years. She has earned a rest.

You might want to crunch the numbers on resistance electric heat. I just removed an OWB and put in Propane Combi-boiler. If resistance electric was my only option I would have moved.