DS Comfort Max 75 - Last effort before replacing

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MH360

Member
May 5, 2016
11
Pennsylvania
I have a DS Comfort Max 75 that I have been battling with for quite some time. This is my last effort before giving up and searching for a new stove. The stove is one of the last models where the data plate says it can burn wood and coal. At the time this was appealing to me because I wanted to keep it for a while and figured there may be a time that I don't want to cut firewood. (after reading posts on this forum I am regretful as I have learned it is difficult to have a stove that burns both well) I have only burned wood in this stove since day one.

Anyhow if you are familiar with the stove, the air is controlled by a bi-metal regulator. The main problem I am having is when I load the stove, the fire takes off and gets quite hot, about 600-650 deg F, before the bi-metal regulator finally catches up. At this point the bi-metal regulator eventually closes completely and after a little bit of time the flames settle and go out. However, the firebox is still really hot and gasses build up and then ignite suddenly. This causes the bi-metal regulator flap to blow open and it pushes pressure on the loading door as you can see a little puff of smoke come out. This will continue to happen unless I turn the regulator to allow air to enter the stove and actually re-ignite.

The above doesn't happen just once in a while, it is quite frequent. Additionally, the burn time of each load is quite short, partially due to me not wanting to load it to the max, given the inadequate control by the bi-metal regulator. I have tried everything in terms of changing up how I use the stove, installed a new bi-metal regulator, I have talked to the manufacturer, and I have talked to other wood stove dealers in the area. One dealer recommended adding a damper but in the manual for the stove, the safety instructions state not to do that. The stove is connected to a Ventis class A 6" chimney which is extends the proper distance above the roof. I appreciate you reading this post and any suggestions or information you may be able to provide. Thanks.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
I have a DS Comfort Max 75 that I have been battling with for quite some time. This is my last effort before giving up and searching for a new stove. The stove is one of the last models where the data plate says it can burn wood and coal. At the time this was appealing to me because I wanted to keep it for a while and figured there may be a time that I don't want to cut firewood. (after reading posts on this forum I am regretful as I have learned it is difficult to have a stove that burns both well) I have only burned wood in this stove since day one. Anyhow if you are familiar with the stove, the air is controlled by a bi-metal regulator. The main problem I am having is when I load the stove, the fire takes off and gets quite hot, about 600-650 deg F, before the bi-metal regulator finally catches up. At this point the bi-metal regulator eventually closes completely and after a little bit of time the flames settle and go out. However, the firebox is still really hot and gasses build up and then ignite suddenly. This causes the bi-metal regulator flap to blow open and it pushes pressure on the loading door as you can see a little puff of smoke come out. This will continue to happen unless I turn the regulator to allow air to enter the stove and actually re-ignite. The above doesn't happen just once in a while, it is quite frequent. Additionally, the burn time of each load is quite short, partially due to me not wanting to load it to the max, given the inadequate control by the bi-metal regulator. I have tried everything in terms of changing up how I use the stove, installed a new bi-metal regulator, I have talked to the manufacturer, and I have talked to other wood stove dealers in the area. One dealer recommended adding a damper but in the manual for the stove, the safety instructions state not to do that. The stove is connected to a Ventis class A 6" chimney which is extends the proper distance above the roof. I appreciate you reading this post and any suggestions or information you may be able to provide. Thanks.
What moisture content is your wood at?
 

MH360

Member
May 5, 2016
11
Pennsylvania
Thanks for the replies. Negative on the coal grates, I have the wood plate installed. Wood moisture is about 18%. I am burning all red oak.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
Thanks for the replies. Negative on the coal grates, I have the wood plate installed. Wood moisture is about 18%. I am burning all red oak.
How tall is the chimney overall? And what is your procedure for measuring moisture content?

Your symptoms sound like weak draft or wet wood
 

MH360

Member
May 5, 2016
11
Pennsylvania
The chimney is 20 ft (5-4ft sections) and is somewhat close to the peak however extends about 2.5-3ft above the peak. To measure moisture content of the wood, I just use a cheap probe style reader. I just checked the wood I am currently burning it is actually in the 8-12% range, not the 18% like I previously posted.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
The chimney is 20 ft (5-4ft sections) and is somewhat close to the peak however extends about 2.5-3ft above the peak. To measure moisture content of the wood, I just use a cheap probe style reader. I just checked the wood I am currently burning it is actually in the 8-12% range, not the 18% like I previously posted.
Are you testing your wood on a fresh split face?
 

rwhite

Minister of Fire
Nov 8, 2011
1,982
North Central Idaho
Ar
The chimney is 20 ft (5-4ft sections) and is somewhat close to the peak however extends about 2.5-3ft above the peak. To measure moisture content of the wood, I just use a cheap probe style reader. I just checked the wood I am currently burning it is actually in the 8-12% range, not the 18% like I previously posted.
Are you bring the wood to room temperature and then checking on a freshly split face?
 

MH360

Member
May 5, 2016
11
Pennsylvania
Yea, the 8-12% was on a freshly split face. I store a couple day's worth of wood in the detached garage and then move it into the house as needed. The temp in the garage is 55 F, so not quite room temp but I assume close enough.
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
Yea, the 8-12% was on a freshly split face. I store a couple day's worth of wood in the detached garage and then move it into the house as needed. The temp in the garage is 55 F, so not quite room temp but I assume close enough.
Have you pulled the firebrick wall out and cleaned the flyash out from behind it in that air passage?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
Yea, at the end of each season I pull all fire bricks out and clean everything.
Ok good I am just trying to figure out possible issues. While I am not a fan of these stoves your experience is absolutely not typical
 

MH360

Member
May 5, 2016
11
Pennsylvania
I certainly appreciate the questions and trying to figure out my problem. I have searched and researched and still have not come up with anything. I fully admit that I am not a pro so any help is greatly appreciated.
 

AlpineWarren

New Member
Dec 17, 2022
8
W00dburn1ing
Wondering if you've made any progress with this issue?

Had a DS installed this week and hoping first burn goes well!

I did read that some will put a small clip or bumper on the door to keep it from full closing maybe because of this ramp up and down?

I also think you want to turn it down a little sooner before it gets that hot? That would slow down the ramp up.

Warren
 
Last edited:

AlpineWarren

New Member
Dec 17, 2022
8
W00dburn1ing
Oh and by the way... 600 degrees is absolute max for this stove... Once you hit about 350 turn the regulator down to 3.5, move the front glass air knob to the middle.

This has kept my stove at 400 degrees for the past 5 hours... With one large piece of white oak.

Just added a second chunk and am seeing how it does.

-- Warren
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
Oh and by the way... 600 degrees is absolute max for this stove... Once you hit about 350 turn the regulator down to 3.5, move the front glass air knob to the middle.

This has kept my stove at 400 degrees for the past 5 hours... With one large piece of white oak.

Just added a second chunk and am seeing how it does.

-- Warren
Where are you taking those temp measurements at? If you are talking stove top temps 600 absolutely isn't max for the top of a steel stove and 400 is really low
 

AlpineWarren

New Member
Dec 17, 2022
8
W00dburn1ing
On top of stove hottest point and my manual says 600 is max operating temp. 400 degrees was my choice because that heated my 1350 square foot home just fine with yesterdays temps (had us at 76 degrees was only 40 outside).

-- Warren

PXL_20221219_155123733.jpg
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
On top of stove hottest point and my manual says 600 is max operating temp. 400 degrees was my choice because that heated my 1350 square foot home just fine with yesterdays temps (had us at 76 degrees was only 40 outside).

-- Warren

View attachment 305559

What were your pipe temps at running that low? I would be worried about creosote buildup. Unless you are actually burning coal as intended
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
I have the dual wall pipe and I think it was around 175 a few feet up.

-- Warren
I am assuming that is on the outside right?

If so that tells us nothing you need an internal measurement from a probe thermometer
 

AlpineWarren

New Member
Dec 17, 2022
8
W00dburn1ing
I am assuming that is on the outside right?

If so that tells us nothing you need an internal measurement from a probe thermometer
Yes - Unable to measure that - Several folks here in the Ozarks are running these this way with wood - A little extra buildup I am sure but they say not bad.

I will also be burning coal so it's a good solution for us.

-- Warren
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
Yes - Unable to measure that - Several folks here in the Ozarks are running these this way with wood - A little extra buildup I am sure but they say not bad.

I will also be burning coal so it's a good solution for us.

-- Warren
You really need to get a probe thermometer. You can make a pretty big and dangerous mess of the chimney if pipe temps are to low
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
31,145
central pa
What temps should I be looking for and what do you do drill a hole in your chimney pipe?

-- Warren
About 350 minimum. 900 max. And yes you drill a hole in the pipe.
 

coaly

Fisher Moderator
Staff member
Dec 22, 2007
4,727
NE PA
Did you try the paper clip trick on the air flap to prevent it from closing all the way? I’m familiar with the guys at DS Machine, and they make good stoves. Not sure what your model uses for the metered air when t-stat is closed, sounds like the air wash is the low setting to maintain temp which is fine. Sounds like it needs to be open farther. Try air wash wide open to see what temps you get.

I have a Hitzer coal stove and Kitchen Queen. Both are Amish built as well. The Hitzer (coal - hopper fed) has the bimetal thermostat along with adjustable air intake on ash pan door. I only use it manually with front intake since when the thermostat opens I feel it wastes too much heat up the stack, but heats quickly. So the thermostat is a high fire only, and I use the front as an idle adjustment opened more for more heat.

The KQ, I added the bimetal thermostat on the back myself. I use that thermostat for starting and oven only to kick up temp in a hurry, and the front original intake as a manual setting once up to temp.

I think any stove with a thermostat should have a manual intake to use as an idle or low setting and only open thermostat for high output using much more fuel.