PID Controller for Operating Limit Control?

Stoker Coal Boilers automatically feed the coal and have controls and pumps just like any conventions boiler. They are intended to be used as a primary heat and often have domestic hot water coils as an added bonus. They can be set up independently or in dual sytem with your existing oil/gas boiler. They can accommodate both hot water base board or steam plumbing.
Posts: 304
Joined: Sun. Mar. 18, 2007 11:28 am
Stoker Coal Boiler: AHS 130
Coal Size/Type: Pea/Anthracite
Location: Schuylkill County

Post Thu. Nov. 29, 2007 2:25 pm

U235a4 wrote:ok I think I may have figured a few things out but let me go thru the running order with how I think your units running.

your unit runs untill it reaches the operating limit of 170 on the L4006a unit and if your using a timer the high limit of 190 won't let the unit run until it falls below that. if the temp goes above 205 the circulator won't run and your dead in the water till the unit cools
The L4006A is the operating limit and has a fixed differential. If the sensed coal boiler water temperature drops below the operating set point the draft blower comes on and runs until the L4006A is satisfied. The high limit is a backup to the operating limit and if the high limit is triggered it cuts power to the operating limit control to prevent operation of the draft blower. If the circulator override is triggered (sensed temperature of the coal boiler water greater than 205) then the circulator for the B coil in the air handler in the out building, as well as the fan in the air handler are turned on and remain on until the circulator override sensed temperature drops below the set point.

I have no timer.

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Posts: 321
Joined: Mon. Oct. 29, 2007 8:26 pm
Stove/Furnace Make: 1958 Axeman-Anderson
Stove/Furnace Model: 260M
Location: South Central PA

Post Thu. Nov. 29, 2007 4:37 pm

Bob, Now that I found the switch to my crystal ball and see why you have your unit wired the way you do. All I can say is that if you don't have excessive draft which you said you don't you'll have to look at your ashing and maybe set it to a cooler setting so it doesn't have as much fresh coal to make a hot coal bed in the unit. now to all the AA AHS people out there if you don't know if you do ignore this but when you cool your ashing or slow it down whether it be anthrastat or timer you also so down pickup on the unit, but you don't have the big over ride problems. When you make your ash hotter or speed up ashing you’ll be putting more fresh coal in the unit you speed heat pickup, but you also with have bigger overrides.

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