Low thimble height/not enough rise

[farmwithjunk]

I've been trying to figure out whats available, what is eligible for the tax credit and what the chimney requirements are.

Looking at the Regency F3500 or F5200 they both require a minimum 36" rise before going horizontal into the masonry chimney. The stove is just under 40" tall but my hole in the block is 48" off the floor on center. I know this wouldn't meet their requirements but does that mean I wouldn't have enough draft with this stove? I'm not sure if I'm willing to punch a new hole through the block (2 layers of cinder block) 3 feet higher.

If I look at the Osburn 3500 manual I'm not seeing any requirements for veritical rise before going horizontal.

Will my 48" high stub work well or work well for any stoves?

 

[begreen]

What is the chimney height above the thimble? Is there a 6" insulated stainless liner already in the chimney?

 

[farmwithjunk]

What is the chimney height above the thimble? Is there a 6" insulated stainless liner already in the chimney?

There is about 17' of chimney above where the Tee will be. I'm in the process of ripping out the 6x9 so I'd have the option for 6 or 8" liner.

I have 13' above ground and approximately 4' below ground level to the inlet.

 

[bholler]

I would just raise the crock now while you are replacing the liner. Just do it right now with a heavy liner and you won't have to mess with it for 30+ years

 

[farmwithjunk]

I would just raise the crock now while you are replacing the liner. Just do it right now with a heavy liner and you won't have to mess with it for 30+ years

Yeah, I realize thats the right answer. I have two layers of cinder block to go through to do that.

Would you recommend leaving the lower hole as a clean out? I dont see see what the issue would be dropping a 2' section below the Tee with a cap on it to make cleaning easy.

 

[begreen]

Yes, do it right. It is not that big of a deal to punch the new hole and then with the new liner you will have a sweet setup. Otherwise, the stove may spill smoke in milder weather. Cleanout is a good idea with another tee at the lower location.

 

[bholler]

Yeah, I realize thats the right answer. I have two layers of cinder block to go through to do that.

Would you recommend leaving the lower hole as a clean out? I dont see see what the issue would be dropping a 2' section below the Tee with a cap on it to make cleaning easy.

Yes I would run the liner down to a second tee to work as a cleanout

 

[Todd]

Is that 36” rise a requirement or recommendation? I think Blaze King has the same thing but it’s a recommendation? Maybe try it first as is if it meets code but I do like the idea of a clean out below the tee.

 

[farmwithjunk]

Is that 36” rise a requirement or recommendation? I think Blaze King has the same thing but it’s a recommendation? Maybe try it first as is if it meets code but I do like the idea of a clean out below the tee.

Looks like a requirement for Legacy, Osburn doesn't seem to even recommend any rise that I saw.

"Minimum vertical of 36" before any offset. Horizontal Maximum of 36" with 1/4" rise per foot."

 

[bholler]

Is that 36” rise a requirement or recommendation? I think Blaze King has the same thing but it’s a recommendation? Maybe try it first as is if it meets code but I do like the idea of a clean out below the tee.

But he is putting a new liner in before hooking it up. It shouldn't really add that much time to the job. Changing it later will be a pain.

 

[farmwithjunk]

Family member has a hammer drill and bits so this shouldn't be as bad as initially thought.

 

[begreen]

Good deal. That's what I would use. You'll feel better knowing the job is done right.

 

[farmwithjunk]

Good deal. That's what I would use. You'll feel better knowing the job is done right.

I guess my only question now is do I do a clay crock or just put my pipe into the block with refractory cement.

 

[begreen]

A clay crock will work as long as the ID clears the snout OD. A section 7" stainless stovepipe could also act as a sleeve. Use 3/8 rope gasket to fill the gap.

 

[BKVP]

In general, most wood stoves are vastly more efficient than they were in the 1970's. This is certainly part & parcel of the emissions regulations first imposed in 1984 for the state of Oregon.

As the efficiencies have increased, we have seen a more troublesome install. This is why you are seeing more and more manuals recommending minimum stack height, liner requirements and vertical rise recommendations prior to horizontal runs.

According to the experts in the test labs, at 83-85%+ efficiency (HHV) you will not draft without assistance.

 

[farmwithjunk]

In general, most wood stoves are vastly more efficient than they were in the 1970's. This is certainly part & parcel of the emissions regulations first imposed in 1984 for the state of Oregon.

As the efficiencies have increased, we have seen a more troublesome install. This is why you are seeing more and more manuals recommending minimum stack height, liner requirements and vertical rise recommendations prior to horizontal runs.

According to the experts in the test labs, at 83-85%+ efficiency (HHV) you will not draft without assistance.

What does "without assistance" mean? Meaning the stove requires a taller/insulated chimney vs being able to burn without any pipe at all?

I did add the higher hole through the 2 layers of block and layer of brick. Just need to clean it up a bit now.

 

[BKVP]

"Without assistance" means that at some point in the future, power vent caps (already available but very costly) would be required in order for wood burning appliance manufacturers to make even more efficient wood stoves.