Firebox on a Diet

With the warmer temps over the past few days I shutdown the stove for a mid winter cleanout. The Harman SF-250 received a thorough vacuum from flue pipe to ashpan. This stove has more BTU's than we need if the temp is above 35*. With early spring on the horizon I decided to reduce the firebox.

The SF-250 has 5 shaker grates that run parallel to the loading door. The shaker linkage is on the left side of each grate with a cast arm that hangs down below the pivot point. I removed the farthest two grates and swapped each end for end. Now with this setup only the first 3 grates rock with the shaker arm. I placed a 1" layer of fiberglass insulation over the 2 stationary grates and 12 full size firebrick and 2 thin size firebrick. This new rear wall of the firebox has about a 1/8" gap to the side walls and is the same height.

The stove has been burning for 24 hours and the house is 75* inside and 25* outside. Over the last two weeks we burned 57# a day. I hope the firebox diet lowers the coal consumption.
Cost of the firebrick $28.
RS

PC12-47E Please keep us informed, for temperatures we are back in the 20's here and headed for the teens; but I wish to do the same with our two grate Hitzer 503 ........ although I will just stop shaking one half ........ that is to say use only one of the two grates. We have been burning 50-60# of nut/day. Best, baldeagle

baldeagle wrote:PC12-47E Please keep us informed, for temperatures we are back in the 20's here and headed for the teens; but I wish to do the same with our two grate Hitzer 503 ........ although I will just stop shaking one half ........ that is to say use only one of the two grates. We have been burning 50-60# of nut/day. Best, baldeagle

The stove has no problem reaching 500*F on the side just under the top edge.
The flue temp is lower by about 15* and the the air temp from the heat collector is about 40* cooler.
At the moment the side temp is 360*, The hot air is 165* and the flue is 135*.
I think it will be ok 10*and up....
RS

I use this: I slide the plate forward, build a new wall using firebrick. Reduces the box by 50% or about the size of a Mark I

Hand fired stoves are as versatile as operators make them! I often bank the fire to one side when the temperature bounces between 40 - 50 to keep one side thicker and hotter longer while the skinny side burns thru the coal at night. This yields a full night time fire and half a fire during the warmer day time. Spread it out at night and repeat.

Once it settles into mid 40s- 60s, I reduce the fire box size with steal plating and fire brick. The grate system is different than the toothed rockers most stoves have so it tolerates this system without removing any parts. I've posted a poor quality video here that shows how it works:

Reducing Grate Area for Spring Burning

The pics are very poor.... The side of the stove @ 400* F.
RS

I use the same set up as Cap in my SF260. The flat piece of steel rests on the top of the grate frame and is suspended slightly above the grate so that the grate will move when shaken. I have two different size reducers so that I can adjust the size of the firebox depending on the average temperature. This arrangement lets me to maintain a deep coal bed during the warmer weather while cutting back on the heat produced and consumption of coal. I expect to be back to the larger reducer (larger reducer? does that make any sense?) by the end of the month or early March at the latest. Joe

Joe in NH wrote:I use the same set up as Cap in my SF260. The flat piece of steel rests on the top of the grate frame and is suspended slightly above the grate so that the grate will move when shaken. I have two different size reducers so that I can adjust the size of the firebox depending on the average temperature. This arrangement lets me to maintain a deep coal bed during the warmer weather while cutting back on the heat produced and consumption of coal. I expect to be back to the larger reducer (larger reducer? does that make any sense?) by the end of the month or early March at the latest. Joe

It does sound funny. Kind of like adding a negetive number when operating CNC machine.

Sounds to me like there are some very clever coal burners out there