Flue Gas Temperature, Can it be used for system OFF control?

[sgschwend]

I gleaned from a recent post that flue gas may indicate when the fire is out after the wood supply is gone. If so a device that can switch on that information could be used to shut down the boiler system or maybe a part of the system. I am not sure this is true or that a switching device may be fooled by the damper being closed. I am looking for a way to turn off my Essex when the wood is gone, but don't want it to shut down if the high temperature set point is reached which switches off the draft fan.

Thanks for the help.

 

[Chris Hoskin]

this commonly used on our boilers. Flue gas temp drops below a set point which tells your system that the wood boiler is out of wood. This turns of the boiler fan and indicates to your system that it should pull heat from storage if storage is being used. Works well.

 

[sgschwend]

Thanks for the reply. So what happens when the damper closes and the draft fan turns off? Doesn't the flue gas temperature drop too?

 

[flyingcow]

My innova is set at 90c=194f(flue temp). This shuts off draft fan. Unit is out of coals for the most part. I can adjust it to a different temp, but 90 was reccomended. Works well. I don't think there is a damper to close on this unit.