Retrofit Hitzer Thermostat to Harman

rberq wrote:Capecoaler, I don't know what it means to "radius the holes", so I guess I won't, or if I do it will be by accident and I won't know I have done it. I think I will have enough airflow now, slightly more than 2 square inches. I did some crude measurements and estimates on my spin draft, and that's more intake area than I ever ran the stove at except for right after loading new coal. As you mentioned, I am curious to see whether the burn pattern and ash buildup change noticeably.

oliver, my brother volunteered to weld the air intake, but it didn't seem wise to do it in the living room with the lace curtains four feet away, and I didn't want to unhook everything to haul it out to the garage. If I decide to undo it, this will be easier.

Yes, I assumed because of the way you went about the add on of the thermostat, it was an "on the spot" install (no welding or torch). Again, NICE JOB!

Westy wrote:Looks good Bob, what was the price of the thermostat?

It was about $80 delivered for all the parts.

Alaska sells the whole thing as a kit for about the same, already set up for bolting on. I bought the Alaska first but sent it back due to what seemed like poor design. The intake door was heavy steel plate, and it rode on crude j-hook hinges. When I raised the door with the chain, then let it back down, often it would not drop into place properly and would leave a big gap at top or side.

Frankly, I am not impressed with the Hitzer quality either. The intake door shuts snugly on one side, but the opposite bottom corner leaves a gap. I haven't checked yet whether it's the door or the intake tube that is out of true. Hopefully it is the tube, and after the heating season is over I will take it off and have it planed by the machine shop.

If I were to do it again, like I said in a previous post, I think I would try parts from the Wonderwood 2931 or similar U.S. Stove model. They are perhaps half the price, and I remember my Wonderwood thermostat as being much lighter-weight parts and working extremely well.

Edit: My apologies to Hitzer. I must have been looking in bad light. When I get down close with a flashlight, I can see that the intake door is closing properly.

Update: The thermostat is working beautifully in this late Spring weather. It keeps a very even, low stove temperature without danger of putting out the fire. We are still having lots of days with temperatures in the 50's and 60's, and nights in the 30's and 40's. I set the thermostat so the stove surface temperature stays about 180 degrees; that seems to be about the minimum where it keeps a stable fire. It keeps the house between 70 and 75 round the clock without any attention. The last load of coal idled for 48 hours and I think it would have gone another 12 to 24.

Yea, I like the Hitzer intake controls. Glad to hear that it is working out well for you.

I've got the Mark II, what are the parts needed to complete this project? Anyone selling a complete kit?

PM rberq, he's the man with the answers--orrrrr call Dean at Hitzer 260-589-8536

lox -

See pictures at the beginning of the thread. I called Hitzer and they sent me a parts list for the 30-95 stove, then I called them and ordered off the list, but I'm sure they could send you the parts without your using the list:

(1) Air intake tube, which is heavy steel like the stove body.
(2) Air intake door, which is lightweight metal -- silvery color in the pictures.
(3) Small hinge that the intake door rides on.
(4) Bi-metal thermostat unit -- the square box with the dial.

There's a little clip that connects the top chain (from the thermostat) to the bottom chain (attached to the intake door). The clip allows chain length to be changed. As I recall, the clip came attached to one chain or the other and I don't think I had to order it separately. But double check to be sure.

Hitzer uses a magnet to reduce fluttering/chattering of the intake door, but I did not buy the magnet and never had a problem with the door. The magnet attaches through two little holes that you can see in the bottom of the intake tube. I blocked the holes because it is surprising how much air they let in.

Told ya rberq had the answers

rberg, so after 4 years of use have you noticed lower coal usage compared to when this thermostat was not installed? How long did it take to figure out the correct setting for the thermostat? Do you find you have to adjust it as the temp gets colder out then re-adjust as the temp gets warmer out?

loxety wrote:rberg, so after 4 years of use have you noticed lower coal usage compared to when this thermostat was not installed?

No, the same coal usage, but more comfortable due to steadier temperature and no more guesswork on where to set the intake spinner.

loxety wrote:How long did it take to figure out the correct setting for the thermostat?

Not a problem. Magnetic thermometer on the stove is what I go by. It doesn't take long to learn what thermostat setting corresponds to what stove temperature. If I was smart enough to take some notes, it would have taken even less time.

loxety wrote:Do you find you have to adjust it as the temp gets colder out then re-adjust as the temp gets warmer out?

Yes, because the thermostat controls the stove temperature and has nothing to do with the ROOM temperature. So, with colder weather, you need a higher stove temperature. Also I found that the thermostat range (lowest to highest) was not adequate for the whole year, so I would shorten the chain by one notch in the coldest months, then lengthen it by one in spring and fall.

Incidentally, I have sold the stove, as it was a bit too small for my space. My replacement stove has basically the same thermostat setup.

freetown fred wrote:Told ya rberq had the answers

True. A learned opinion on every subject, but folks don't always listen as attentively as I might expect.

Just bought a Mark I today, you got me thinking now!!!

I don't understand why Harman doesn't have this as an option for their stoves. I've been trying to think up a design for a device that would control the air intake by the room temp. I see there is Coal-tron a electronically controlled device for the stokers. I guess Harman forgot about us hand fired folks.

loxety wrote:I've been trying to think up a design for a device that would control the air intake by the room temp.

Somewhere I think I posted a thread to do this. Basically, a room thermostat to turn on/off a fan, with the fan blowing on the bi-metal thermostat. So, room temperature drops, fan comes on and cools the bi-metal, tricking it into admitting more air to the fire and producing more heat. Then when the room warms up, fan goes off, bi-metal thermostat realizes the stove is too hot and reduces combustion air.

I experimented with it but it didn't work very well, mainly (I think) because I wasn't using the proper size fan and wasn't directing it only at the bi-metal thermostat. I think it would be better to use a small fan and duct the air directly into the bi-metal housing. Also I ran afoul of the fashion police by attaching my room thermostat to the piano and running a bunch of ugly wires across the living room. The bottom line, I think, is that a hand-fed coal stove is very good at producing steady heat, and not quite as good at cycling up and down in response to a room thermostat, so there was little benefit in my experiment. You're welcome to try and refine the technique.

grizzly2 wrote:

rberq wrote:Capecoaler, I don't know what it means to "radius the holes", so I guess I won't, or if I do it will be by accident and I won't know I have done it.

I think Capecoaler must have some engine modification background. Radius the holes would be the equivalent of porting and polishing the intake ports on an engine head and intake manifold for better air flow. I suspect he is saying it "tounge in cheek".

That's exactly what he meant (here is a photo provided by my family that shows what he meant by "radius the holes")... and tell Bro to clean up that slag! He was just being funny with you and made me laugh its a great job, well done!