HHW boiler modulating burner control
HHW boiler modulating burner control
(OP)
Heating hot water system has a boiler with modulating burner control and a 3-way valve on supply pipe to reset bldg supply water temp based on outside air. I have two questions:
1. My understanding is that the conventional way of controlling the burner,whether there is a 3-way valve or not, is by leaving boiler supply water temp; is this correct? The contractor is using return water temp to modulate the burner.
2. The boiler keeps shutting down on hi-temp limit. Could this be happening because the 3-way valve bypasses so much water around the boiler that the flow switch opens up shutting down the boiler?
Thanks for your help
1. My understanding is that the conventional way of controlling the burner,whether there is a 3-way valve or not, is by leaving boiler supply water temp; is this correct? The contractor is using return water temp to modulate the burner.
2. The boiler keeps shutting down on hi-temp limit. Could this be happening because the 3-way valve bypasses so much water around the boiler that the flow switch opens up shutting down the boiler?
Thanks for your help





RE: HHW boiler modulating burner control
RE: HHW boiler modulating burner control
The boiler must operate above a minimum temperature to avoid the problem of the flue gases condensing within the heat exchanger and boiler flue system. If the flue gases do condense, the result is hydrochloric acid, this will result in rapid failure of the boiler heat exchanger and the flue system.
To avoid this occouring, the boiler should be operated at a higher temperature. If you wish to reset the heating water circulating temperature, then you use the 3-way valve arrangement. Ideally, you should create primary and secondary water circuits.
Cheers,
Cooky
RE: HHW boiler modulating burner control
RE: HHW boiler modulating burner control
Kico!
I think the control scheme you already have, seems to be ok except that your boiler capacity is high as noted by Imok.
Regards,
RE: HHW boiler modulating burner control
Hope this helps a bit
Tony