Boiler Control, I'm Stumped

[Robby]

I have a wood boiler, Harman SF360, and I just purchased a 1100 gallon water storage tank. Boiler to tank, tank back to boiler and pump in the middle.
Heat for house, separate circuit, tank to house and return.

My problem: how to I tell the pump the boiler is lit - RUN, boiler is out -STOP.
An aqua-stat would just tell the pump to keep on running until storage tank is down to set point. There would be huge heat loss keeping the boiler at temp with stored BTU's.

I am stumped.

Robby

 

[KsWoodsMan]

Maybe put a thermocouple or thermopile in the exhaust flue operating a small relay, so the pumps wont run till it is up to temp ? :dunno:

 

[mtfallsmikey]

Does the boiler:

Have a draft induction fan?
Damper/solenoid?

Whichever...could come from the relay(?) to power another relay....need more info, and coffee!

 

[Robby]

I'm Stumped

Maybe put a thermocouple or thermopile in the exhaust flue operating a small relay, so the pumps wont run till it is up to temp ? :dunno:

Good Morning

The exhaust/chimney temperature is an excellent idea. Do you suppose a snap disc would stand the higher temps? I don't know much about thermocouples. I will do some research.

Robby

 

[Robby]

I'm Stumped

Does the boiler:

Have a draft induction fan?
Damper/solenoid?

Whichever...could come from the relay(?) to power another relay....need more info, and coffee!

Hi,

The boiler has a Johnson Controls set up that operates a 120V motor that opens a draft door. It is set now to open door at about 173 F and close at 180F. As the fire dies the door opens and stays open until power cut or water temp up to 180F.

Thanks

Robby

 

[Butch(OH)]

I am no switchgear expert but the entire control logic of my Woodmaster OWB is run by a small programmable controller in what they call the "ETC" unit. It is outsourced so I assume available for anyone to purchase? Anyway one of the features that sold me on Woodmaster is that the controller will shut the draft down at a settable temp so if you run out of wood it will not lose all the stored heat due to the draft running open. I would assume that anyone with some controll experience could take that unit and adapt it to your system and you could set it to shut the pumps down at any temp you wish.