Adapting Bimetallic Thermostat Draft Control to Warm Morning

freetown fred wrote:Orrrr, you could order the whole bi-metallic assembly from HITZER---it's been done & worked well on different stoves

What fun is that for a tinkering type ?

Paul

Fred, none of that talkin' sense in here. I already have a bimetallic thermostat and am already working on fabrication of the rest. Shouldn't be a big deal at this point.

Paul, I have used Ferro before, along with some other eutectic, low-melting-temp alloys for casting. It is pretty sweet stuff but man does it cost a pretty penny.

Yes it does !

I was lucky. I had a metallurgist brother-in-law who got me a small batch free.

Paul

Even with havin the thermo, you got a fair amount of thinkin & tinkerin to do--& YES, that is the fun part

Paul, that hole in your pics looks to be something like 2 inch diameter. Do you remember how large that is? When I get a chance to cool the stove enough to get measurements, I'll figure what area I'll start with.

I may have figured out a way to mount without disturbing the sheet metal of the stove. The upper portion of the stove consists of louvered sheet. I may be able to slip nuts and washers or a carriage bolt through the back of that and have the thermostat up high. I don't know if the increased airflow there will negatively impact the thermostat but, even if it doesn't work there, it's an easily reversible modification.

Is not the bi-metallic coil mounted directly to the stove's wall for sensing and responding to temps?
Lots of stove pics posted here w/ coils installed.
Riteways, Hitzer 82 & 55,30-95,50-93, DS has many as well.
Look at Hitzer web site for good pics of all their's.

Yes, mine worked trouble free for over 30 years right up until I got up there in age, tired of tending the hand fire and switched back to my current girlie stoker stove

I noticed the pictures I posted are rotated 90 degrees, I hope that wasn't confusing.

I ran the stove with the bimetal coil thermostat and a barometric Damper and although the flap is lightweight I never had it flutter. As far as over temperature ......... The only time it ran away is the time I forgot to close the ash door

I don't think a fusible link would have helped me that time unless I used it to trigger an alarm or motorized actuator to close my ash door !

The hole on mine is 1-1/2" and can be drilled in with a hole saw . You can also toggle bolt your bimetal thermostat on thru the slots in your outer housing . Is yours adjustable ? If it's like mine I can adjust it down even if the fire isn't burning.

Can you post a picture of your thermostat? There are a tremendous amount of talented forum members here and pictures will help you gain more ideas.

Paulie

I have a 400 WARM MORNING AND THE PORT FOR THE BIMETALIC IS IN THE SIDE OF THE ASH PAN. tHER IS A tube that comes out and a light flapper on it that is conected to the spring . All very light and it works very well. You might find one of these on a 400 or a 420 model and they should adapt to your stove. Does your model have a cabinet. The models that use the thermostat are all the cabinet type. I hope that helps.

Coalturkey, my currently running 818 is jacketed but does not have a full-blown cabinet like a 400 or 460 do. The ash door and load door are both exposed by design.

My 460 that will be fixed up over the off-season does have a cabinet.

Thanks for the insight!

voodoochylde wrote:Anyone have any insight or alternate ideas?

Find one of the old Wonderwood / Ashley / Locke circulator stoves with a bi-metal thermostat, and see how they were set up. As I recall, my Wonderwood had the thermostat attached directly to the sheet metal of the firebox, with a wire running to an air intake below the grates, where there was a light-weight flapper door lifted by the thermostat coil.
See also my thread from a few years ago: Retrofit Hitzer Thermostat to Harman
The parts on the old Wonderwood were much lighter and more "delicate" than the Hitzer parts.

So I got brave and started hacking my parts together. I cut a 2 inch diameter hole centered 3 inches below the grate. I used a section of 3x3x1/4 box steel for my intake with two mounting ears. The flapper was fabricated on my table (man I wish I had a brake) and was made from 22ga mild steel. I used a 1 inch hinge to act as a pivot. The silicone is curing between the intake and a piece of wax paper with the flapper resting on it now.

The thermostat uses ceiling fan chain but isn't connected and I've not even thought of tuning yet. It's mounted to the side of the top area of the firebox in another bent-in-the-kitchen chunk of 22ga steel sheet. I used 4 10-32 screws, 3/4 long and fender washers backed up by lock washers and nuts. All hardware is stainless.

As it turns out, there is NO cast iron below the firebox and grate. It's something like 18 or 16 gauge steel and cut very well. I used my automatic center punch to break the porcelain for both the pilot and the hole saw.

As I'm running a very low fire right now and have to babysit my little sister tonight, I won't start playing until probably around 11. Wish me luck!

Thank you all for your ideas and feedback. I'll update as I gain experience with this system.

Sounds great
Get us some pictures to see.

voodoochylde wrote:... I've not even thought of tuning yet.

I have had two different thermostats on two different stoves, and neither one had the range to handle both warm and cold weather. The chain needs to be shortened by one or two balls when the weather turns from fall to winter. An adjuster at one end or in the middle of the chain will make the adjustment easy and quick. See Type B Couplings at the link below, as one example. There are nicer adjusters provided by Hitzer and DS Machine, but I can’t locate an internet link to one. Basically, you can leave one end of a connector un-crimped so the ball can easily be slipped out and a different ball slipped in, and just leave the excess chain dangling.
http://www.ballchain.com/chain_attachments.html

IT LIVES!

It's controlling the stove right now. Still roasting some volatiles off a hod of nut bit. It's sitting at 300 with the flapper as the sole source of combustion air. No pics yet. Not sure if I can post such embarrassingly poor craftsmanship...