keystoker boilers

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lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Mon. May. 09, 2022 11:31 am

After much thought and 10 days of observation I would like to share the recent hopper modification of my kaa-4-1 coal stoker.

As the hopper is rotting away I need to replace it and I decided to experiment with the coal feed, SO I thought why not try this as its near the end of the heating season?

I purchased 2 pieces of 1/8" by 6" by 3" steel flat stock and placed the full 3 inch width on both sides of the hoppers draw point/throat reducing the hoppers draw point width by 6 inches.

Next fall l will be reducing the size of the draw point more by using the extra 2" flat stock I have in addition to the 3 inch flat stock to see how well that goes.

I have forgotten what the draw point dimensions are of the hopper but I can always go back and measure the dimensions as I did not measure them when I placed the 2 pieces of 3" wide flat stock on the hopper opening.

I no longer have partially burned or unburned coal pouring over the sides of the stokers firebed and the coal is evenly spread across the firebed as it burns and the coal fire seems to be burning hotter as well as it seems to be reaching the high limit temperature much faster.

My little experiment was a success and I will be using the same method next heating season.

Some backround information.

I use bagged Blashack Rice Coal for heating fuel

1. The combustion air passageway under the fire bed is clear of flyash and coal fines.
2. The stoker motor was replaced at the start of the 2021-2022 heating season. The combustion air blower is the same fasco
blower the kaa-4-1 boiler came with
3. a. The boiler has an L8124L double aquastat and a McDonnel and Miller RB-122-E Low Water Cut Off that replaced two
defective hydrolevel 3250 plus digital aquastats
b. The high limit temperature is set at 170 degrees Fahrenheit with a 10 degree differential
c. The low limit temperature is set at 150 degrees Fahrenheit
d. The dump zone is controlled by a honeywell L6006L single aquastat and set at 190 degrees Fahrenheit with a 10 degree
differential

Prior to the minor modification I made in the hopper I found that with the stoker slowed down to 12 threads out I have still spilled a great deal of unburned coal over the side plates of the 3 fire bed wide stoker. I collected this coal when I clean the ash pit and put the unburned coal back in the hopper. I am burning less coal to heat my home.

The 4 gallon pails I use are Behren galvanized pails and they need to be replaced as they are pitting and becoming weaker and have small holes in them.

The 4-gallon pails are small enough that I set the lip of the pail just under the edge of the three bed stoker to collect the ashes.

I have seen no unburned coal in the pails when I change them out. I change them several times per day sometimes and use the empty coal bags for the ashes.

I can only guess how much good coal I lost in the bushel ash baskets prior to changing to using the four gallon pails to collect the ashes 3 years ago.

 
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sterling40man
Member
Posts: 1645
Joined: Sat. May. 03, 2008 11:52 am
Location: Northern Maine
Stoker Coal Boiler: Keystoker K6

Post by sterling40man » Mon. May. 09, 2022 1:13 pm

Interesting. Any pics of these mods?


 
lzaharis
Member
Posts: 2366
Joined: Sun. Mar. 25, 2007 8:41 pm
Location: Ithaca, New York
Stoker Coal Boiler: Keystoker KAA-4-1 dual fuel boiler
Hand Fed Coal Boiler: former switzer CWW100-sold
Coal Size/Type: rice
Other Heating: kerosene for dual fuel Keystoker/unused

Post by lzaharis » Mon. May. 09, 2022 3:57 pm

I do not have any pictures of the flat stock resting on the hoppers draw point
opening but there is plenty of sheet metal on the hopper base sheet metal to
rest the 3" Wide by 6" Long flat stock on.

The Honeywell horizontal L8124L double aquastat is mounted to the left of the
McDonnel and Miller RB-122-E LWCO; the 3/4" tapping has a dry well filled with
the Honeywell supplied conductive paste which provides me with more assurance
the double aquastats bulb is sensing the actual temperature in the boiler water.

The McDonnell and Miller RB-122-E Low Water Cut Off is in the 3/4 tapping above
and to the right of the oil burner mounting weldment. This LWCO's sensor tab is
immersed in water and more reliable in my opinion based solely on my past
experience with the 2 failed hydrolevel 3250 plus units.

The Honeywell L8124L double aquastat is located over the fire viewing door.
I have to buy a small piece of right angle sheet metal to act as a small heat shield
for both the double aquastat and the Low Water Cut Off.

If your k6 hopper has the drawpoint hole in the bottom with the tabs that have to
be hammered back there is no reason it should not work for you as well.

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