Custom Designed Stove - Worth staying with it?

mewop

New Member
Nov 19, 2020
2
NC
We moved to a home that was originally owned by an engineer. It appears he loved to DIY as there are a lot of nice little things he has done with the house. When I hear DIY, I generally think was probably done poorly but this guy was pretty impressive from what I have experienced thus far.
One of the things he created was his wood stove. Rather than blindly trusting that this was safely designed, I wanted to get some input on what you guys think. I know there is likely optimal dimensions for firebox design, flue diameter, etc which likely has a huge effect on efficiency

Our home is two stories plus a basement. Home built in 1990. Primary heat source is LP - this stove is just supplemental. Previous owners were here about 10 years- noted to not use stove very often - usually just on weekends. No idea on use frequency prior to that. Stove felt to be built by original owners so it is quite old. Stove is in the basement which is unfinished- cinder block walls, concrete slab, sheet rocked ceiling. The chimney traverses all 3 levels in the middle section of the house- one face of it is exposed on the 3rd floor but otherwise it is inside. There is a second flue inside but it is not used. Chimney was recently inspected and in good condition without any significant creosote buildup.

The stove is square and constructed from 1/8" steel. External dimensions are 33x38x30". Firebox dimensions are W29 x L28 x H26. As best I can tell, around the firebox there is about 4" space in each dimension except in the back where the air ducts are located. No idea if there is anything inside there. The floor and half of the walls are lined with standard sized firebrick. There is no exhaust damper. Exhaust flue is 8" diameter. There is a small square shaped piece of metal below flue (photos). There are two rotating knobs for draft control.

On the side, there are two 8" openings for air ducts which feed into the first floor HVAC. Air is ran not by the hvac fan but by a fan several feet from the stove. Heat output is very good, albeit noisy. It can easily keep the first floor toasty but getting the warmth to the second floor is more of a challenge. There is a an access panel on the back to access the inner airflow section.


A few of my concerns-

Do you think it is worth staying with this stove or would I be better served upgrading to a newer, more efficient model?

Creosote is always a concern and with having a 3 story chimney, I really would prefer to run hotter to keep temps up. I have NO problem quickly getting flue temps (measured externally of course) to 350+ and can easily get to over 500 with the draft control open at 3/4, especially with a fast burning wood type.

In regards to the air duct and steel construction, any issues you see with running this occasionally hot (600ish) to try and burn off any creosote buildup? Definitely would have fan on - I've seen the duct thermometer get close to 120C (250F) when I have not had the fan on

Is it more efficient with a firebox of this size to pack it full and control burn temps vs having a smaller fire and letting it open?

Other than it being a devourer of wood and smoke getting out when I am first getting the fire started and open the door too quickly, I am happy with the stove. We have plenty of wood on my property from the occasional downed tree.

Other thoughts? Thanks everyone!!

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bholler

Chimney sweep
Staff member
Jan 14, 2014
22,549
central pa
We moved to a home that was originally owned by an engineer. It appears he loved to DIY as there are a lot of nice little things he has done with the house. When I hear DIY, I generally think was probably done poorly but this guy was pretty impressive from what I have experienced thus far.
One of the things he created was his wood stove. Rather than blindly trusting that this was safely designed, I wanted to get some input on what you guys think. I know there is likely optimal dimensions for firebox design, flue diameter, etc which likely has a huge effect on efficiency

Our home is two stories plus a basement. Home built in 1990. Primary heat source is LP - this stove is just supplemental. Previous owners were here about 10 years- noted to not use stove very often - usually just on weekends. No idea on use frequency prior to that. Stove felt to be built by original owners so it is quite old. Stove is in the basement which is unfinished- cinder block walls, concrete slab, sheet rocked ceiling. The chimney traverses all 3 levels in the middle section of the house- one face of it is exposed on the 3rd floor but otherwise it is inside. There is a second flue inside but it is not used. Chimney was recently inspected and in good condition without any significant creosote buildup.

The stove is square and constructed from 1/8" steel. External dimensions are 33x38x30". Firebox dimensions are W29 x L28 x H26. As best I can tell, around the firebox there is about 4" space in each dimension except in the back where the air ducts are located. No idea if there is anything inside there. The floor and half of the walls are lined with standard sized firebrick. There is no exhaust damper. Exhaust flue is 8" diameter. There is a small square shaped piece of metal below flue (photos). There are two rotating knobs for draft control.

On the side, there are two 8" openings for air ducts which feed into the first floor HVAC. Air is ran not by the hvac fan but by a fan several feet from the stove. Heat output is very good, albeit noisy. It can easily keep the first floor toasty but getting the warmth to the second floor is more of a challenge. There is a an access panel on the back to access the inner airflow section.


A few of my concerns-

Do you think it is worth staying with this stove or would I be better served upgrading to a newer, more efficient model?

Creosote is always a concern and with having a 3 story chimney, I really would prefer to run hotter to keep temps up. I have NO problem quickly getting flue temps (measured externally of course) to 350+ and can easily get to over 500 with the draft control open at 3/4, especially with a fast burning wood type.

In regards to the air duct and steel construction, any issues you see with running this occasionally hot (600ish) to try and burn off any creosote buildup? Definitely would have fan on - I've seen the duct thermometer get close to 120C (250F) when I have not had the fan on

Is it more efficient with a firebox of this size to pack it full and control burn temps vs having a smaller fire and letting it open?

Other than it being a devourer of wood and smoke getting out when I am first getting the fire started and open the door too quickly, I am happy with the stove. We have plenty of wood on my property from the occasional downed tree.

Other thoughts? Thanks everyone!!

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Is there a cold air return attached to the circulation fan or is it just pulling room air?
 

begreen

Mooderator
Staff member
Nov 18, 2005
85,058
South Puget Sound, WA
It's a big, box with a convective jacket through which the blower circulates air. The firebox is pretty primitive with a tiny baffle. Not much efficiency here. Might have been good for 1975, but not so great now.
 

ABMax24

Minister of Fire
Kudos to the guy for building such a thing. But my back hurts at the thought of processing enough wood to feed that beast.

What does worry me is the jacket around the firebox, I'd be pulling off the rear panel to have a look, should there be a crack in the firebox there is a real risk of smoke or carbon monoxide being blown through the house from the ducting. I also don't see welds on the inside of the firebox, that scares me, I'd assume the plates were but up tight, welded from the outside and then ground flush like they were on the outside jacket. If that's the case there is very little weld material holding that firebox together.
 

Corey

Minister of Fire
Nov 19, 2005
2,506
Midwest
Guess a lot depends on how you define 'worth'. Worth peace of mind that it won't split a DIY weld from some unknown individual and spark a fire in the middle of the night? Worth gaining more heat from less wood with a modern stove? Worth something more aesthetically pleasing - either in the black box itself and/or view of the fire? Worth less smoke emissions? Worth cost of a new(er) stove?

Hard to guess on all of these. You could certainly install a nicer looking, more efficient, safer stove with a great view of the fire. Though obviously at some additional cost. However, if you go to sell the house, a nice stove might actually be a benefit whereas this would most likely be a net zero, or even a detraction for a new owner.
 

mewop

New Member
Nov 19, 2020
2
NC
Thanks everyone for your input

There are two points for cold air return - one directly above and secondly the door to main floor

I will look at pulling the back panel - I was a bit worried stripping a rusty screw if it has not been touched in a while but the risk of a crack would present a larger problem. With all of the LP appliances - central air, stove, instant water heater, small gas stove.. We do have CO detectors all over the house in bedrooms, basement, living room etc.

Looking closer, the walls and floor are actually 1/4" thick. Welds are there on all 4 corners on the outside. I should probably see if I can pull some firebricks or try to fish an endoscope underneath to verify integrity of the other corners as well.

I need to do more research in the stove section on the newer types of stoves - the second chimney flue is in the dining room behind the sheetrock. It would be nice to have a small stove there. I would probably end up running that most of the time as there would not be as much difficulty moving the heat upstairs.

Yea that does look like copper RTV---- former owner job. It is about to fall off. If it was leaking it has since self-sealed on the inside otherwise I should be seeing some leaking smoke

I see what you mean about the baffle-- it is TINY compared to new stoves. I probably am losing a significant amount of heat essentially straight up the chimney!
 
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