Harmen mark 3 to a chubby ?

TFL · Post by **TFL** » Thu. Feb. 09, 2023 12:30 pm

new to the forum, I have a harmen mark 3 in my house now, have used it for 4 yrs, after 19 yrs heating with wood. as all know here it is a great change to heat with coal, vacation like

the mark 3 is just too big, house is 940 square ft and I struggle to get the house below 78 when the stove is running, even with single digit temps outside. most other times I have a window open
just wasting coal feeding it
I found a dealer who has a chubby in stock, seems like it would be a better fit
some confusion on my part, the harman states never to put a flue baffle in place
yet the chubby manual states a baffle is necessary
isn't it dangerous to run a flue baffle in a coal stove?
or is it just the design of the chubby that allow it

waytomany?s · Post by **waytomany?s** » Thu. Feb. 09, 2023 12:33 pm

Baffle? Or manual pipe damper?

TFL · Post by **TFL** » Thu. Feb. 09, 2023 12:37 pm

yup, manual pipe damper, my bad

waytomany?s · Post by **waytomany?s** » Thu. Feb. 09, 2023 12:43 pm

Somewhere recently sunnyboy explained that very well. You want to follow your manufacturers recommendations. From what I've read, the chubby stove has a tendency to draft really well, so a mpd would help slow things down.

TFL · Post by **TFL** » Fri. Feb. 10, 2023 8:12 am

interesting that the chubby may draft well, wonder if it is the design of the fire pot
seems from pictures that it is tapered

so this is what I have resorted to with the mark 3, I am a steel fabricator, so I cut a couple of
8 x 6 x 3/4" angles , tried that out, then made an adjustment to the bottom legs cutting them to
5-1/4" , gives me a 9-1/2" opening that holds the house at 70 degrees in milder temps
lows upper 20's at night
I cut them so they lay on top of the lip that surrounds the fire box, keeps the angles 1/4" or so above the grates and allows the grates to shake as they should

.JPEG | 61.3KB | image0.jpeg

although this is working well, just seems the stove wants that full bed of coal, and wants to run
at 450-500 degrees, then it rocks, just too much heat for the house

with these angles the stove is running at 275-350

warminmn · Post by **warminmn** » Fri. Feb. 10, 2023 9:06 am

Before you switch out the Harmon, try a few things to run it lower. Making the firebox smaller as an example. Its been a while since I saw a pic of the grates in one, but most stoves you can make the grate smaller with firebrick or steel somehow. Im betting theres a topic on this forum about doing that with your model stove.

Its a lot better to have too much heat than not enough. The nice thing about making your present stove work is if you have a week of record breaking cold you can just undo you modification and still be warm. A smaller stove you have to push too hard sometimes.

D-frost · Post by **D-frost** » Fri. Feb. 10, 2023 10:32 am

TFL,
Keep what you have......it does the job, and, it 's nice to have more, than not enough. Modify it to your liking.
There is a thread on here, where a member dis-connected the linkage to the rear grate, and, added firebrick to decrease the box size, making the stove burn less coal, thus decreasing the heat output. Type Harman in the search box(top right)....lotta info there. I've had a Chubby, a "good" small stove, and now have a Harman MKII.......the Harman will give you more time between tending, and, if you burn wood, the Harman is much better than the Chubby....just my opinion.
Cheers

warminmn · Post by **warminmn** » Fri. Feb. 10, 2023 10:53 am

Sorry TFL, I read your post right above my last one wrong, thinking you were talking about the stoves legs. You are already on the right track, you just need to try things like Dfrost just mentioned.

TFL · Post by **TFL** » Fri. Feb. 10, 2023 12:02 pm

D-frost wrote: ↑
Fri. Feb. 10, 2023 10:32 am
TFL,
Keep what you have......it does the job, and, it 's nice to have more, than not enough. Modify it to your liking.
There is a thread on here, where a member dis-connected the linkage to the rear grate, and, added firebrick to decrease the box size, making the stove burn less coal, thus decreasing the heat output. Type Harman in the search box(top right)....lotta info there. I've had a Chubby, a "good" small stove, and now have a Harman MKII.......the Harman will give you more time between tending, and, if you burn wood, the Harman is much better than the Chubby....just my opinion.
Cheers

thanks your saving me some money for sure,
yes the mark 3 is a really good wood stove , I have burned a bunch thru it in milder temps

ShawnLiNy · Post by **ShawnLiNy** » Fri. Feb. 10, 2023 3:53 pm

I was able to use regular leftover concrete pavers around the back and sides of my massive 100k Btu stove that’s in maybe 300sf garage I’m sure they’ll decompose over time but no issues after 2 months and free and effective

Post by **Rob R.** » Fri. Feb. 10, 2023 4:04 pm

TFL wrote: ↑
Thu. Feb. 09, 2023 12:30 pm
some confusion on my part, the Harman states never to put a flue baffle in place

I'm sure the lawyers made them put that in there. A manual pipe damper would probably help you dial the stove in to a more moderate temperature, but I understand the desire to follow the instructions.

Do you have a barometric damper installed? The Mark III manual recommends the use of one to control excessive draft.

waytomany?s · Post by **waytomany?s** » Fri. Feb. 10, 2023 4:24 pm

Instructions are important

zachary193 · Post by **zachary193** » Fri. Feb. 10, 2023 5:12 pm

TFL wrote: ↑
Fri. Feb. 10, 2023 8:12 am
interesting that the chubby may draft well, wonder if it is the design of the fire pot
seems from pictures that it is tapered

so this is what I have resorted to with the mark 3, I am a steel fabricator, so I cut a couple of
8 x 6 x 3/4" angles , tried that out, then made an adjustment to the bottom legs cutting them to
5-1/4" , gives me a 9-1/2" opening that holds the house at 70 degrees in milder temps
lows upper 20's at night
I cut them so they lay on top of the lip that surrounds the fire box, keeps the angles 1/4" or so above the grates and allows the grates to shake as they should
image0.jpeg

although this is working well, just seems the stove wants that full bed of coal, and wants to run
at 450-500 degrees, then it rocks, just too much heat for the house

with these angles the stove is running at 275-350

How do you shake ashes with those steel plates blocking ? I would think that it would be harder to shake with a flat plate over the grates . How low can you dial it down in temperature ? My ds came with a plate for wood fires . You can’t shake it with that plate in or it lifts up and gets ash under it and lets more air in . Can you run the Harmon stoves down under 200 degrees ?

TFL · Post by **TFL** » Fri. Feb. 10, 2023 5:15 pm

Do you have a barometric damper installed? The Mark III manual recommends the use of one to control excessive draft.

I don't have one , same chimney system has been in place for 23 yrs, with no over firing
so I would say I am ok without it

Post by **Rob R.** » Fri. Feb. 10, 2023 5:27 pm

The stove runs hotter than you want even with the inlet damper closed? I would install a baro and see how that does before buying a new stove.