It's been three month that 222-F had been installed in my ranch-style house, with no basement. The boiler is in a 4' x 5' small room, call it a boiler-room from here on, it is part of the house like a closet.
The boiler-room does not have its own radiator/baseboard, but the temperature in the room does not fall under 60F. Most of the times, the temperature in the boiler-room is higher than that.
For the first couple of month the boiler operated in a predictable fashion. The thermostats in either of the two zones call for heat, once the set room temperature reached, the boiler would shutoff after couple of minutes. The DHW operated in similar manner.
As of late, when the outdoor temperature is under 37 F and the room temperature(s) reached, the boiler does not shut off. The fan stays running with the burner turning on occasionally for a short period of time. This is the explanation of the reason from my contractor, quote:
According to Viessmann the boiler is doing exactly what it was designed to do. I talked with them this morning. I was correct in assuming it had something to do with the freeze protection. Under 37 degree the fan comes on. They claim that they want it to run all the time under 37 it is also making water for the reserve tank but at a extremely low firing rate instead of making the boiler fire to high fire. They assured me it is doing what it was designed to do
Why would the 222-F have 20 gallons, well insulated DHW reserve tank in this boiler, if the system need to continiuosly heat the water in the reserve tank? It is only at the time, when the outdoor temperature is under 37F.
The boiler is within the house, why is the freeze protection activated?
Just the containiously running fan in 24 hours uses ~ 3 KWh during this time, just like in the case of yesterday. The burner running power utilization is additional to this. Under normal circumstances, when the outdoor temperature is over 37 F, the boiler uses about 0.5 KWh. The freeze protection may effectively offsets any energy efficience that the boiler may have in NG.
Is there a way to disable the freeze protection? If not, can the outdoor temperature be set to a more reasonable value, like 33 F, or less?
TIA...