JHZR2
Staff member
Hi,
Per my other threads, we have a new modulating/condensing HW boiler. It has an outdoor reset and is set with the knowledge that he have cast iron radiators, so the manufacturer recommends a max design setpoint of 160F for typical operation.
We were away for the long weekend, and the house was about 55F. We got home and set it back to 65F.
The boiler has logic that puts it into "boost" mode if the house temperature is not achieved in a certain amount of time. Instead of having a water setpoint of 160F, if after 20 minutes it is not achieved, the setpoint will temporarily go to 178, and if not achieved after another 20, then to 195 (max boiler temperature set). I know that 180F is just fine as that was the aquastat temp on our old boiler, but I prefer the lower design point for operating in a better condensing mode and providing more gentle heat.
Since the house was cold and is only one zone, it was heating up and then went into boost mode one and then boost mode two. After about 180F, the pressure got to 30 psi (sitting cold this system is 20 psi - our old cast iron boiler system was 12). It started venting water then as a result out the pressure valve.
I dont know how much came out, but it was a constant trickle for many minutes as the system ran.
So, after all this typing, my question - is this a common thing because the system really hit max temp for the first time (all other cycling since new has been pretty slight, never taking water temperature above 160ish). Since there is an expansion tank, a water filler valve, etc., could it just be that everything has to cycle and leak once or twice so that the pressures all balance and operate, or is something not right?
My old system was at 12 psi and always 12 psi, even when hot as I recall. The only time it vented was when my autofill valve got stuck open and took the system to too high a pressure, causing it to release when the heat cycled.
So my new system is higher design pressure and swings more it seems when run hot and long to take a house back up to a normal temperature from a reduced one. But do I need to worry about this, or will everything come into balance?
I would prefer to close the water fill valve to prevent the potential for water all over if a leak was ever sprung (this is an old house so you never know).
What should I be watching/asking/thinking/doing?
Thanks?
Per my other threads, we have a new modulating/condensing HW boiler. It has an outdoor reset and is set with the knowledge that he have cast iron radiators, so the manufacturer recommends a max design setpoint of 160F for typical operation.
We were away for the long weekend, and the house was about 55F. We got home and set it back to 65F.
The boiler has logic that puts it into "boost" mode if the house temperature is not achieved in a certain amount of time. Instead of having a water setpoint of 160F, if after 20 minutes it is not achieved, the setpoint will temporarily go to 178, and if not achieved after another 20, then to 195 (max boiler temperature set). I know that 180F is just fine as that was the aquastat temp on our old boiler, but I prefer the lower design point for operating in a better condensing mode and providing more gentle heat.
Since the house was cold and is only one zone, it was heating up and then went into boost mode one and then boost mode two. After about 180F, the pressure got to 30 psi (sitting cold this system is 20 psi - our old cast iron boiler system was 12). It started venting water then as a result out the pressure valve.
I dont know how much came out, but it was a constant trickle for many minutes as the system ran.
So, after all this typing, my question - is this a common thing because the system really hit max temp for the first time (all other cycling since new has been pretty slight, never taking water temperature above 160ish). Since there is an expansion tank, a water filler valve, etc., could it just be that everything has to cycle and leak once or twice so that the pressures all balance and operate, or is something not right?
My old system was at 12 psi and always 12 psi, even when hot as I recall. The only time it vented was when my autofill valve got stuck open and took the system to too high a pressure, causing it to release when the heat cycled.
So my new system is higher design pressure and swings more it seems when run hot and long to take a house back up to a normal temperature from a reduced one. But do I need to worry about this, or will everything come into balance?
I would prefer to close the water fill valve to prevent the potential for water all over if a leak was ever sprung (this is an old house so you never know).
What should I be watching/asking/thinking/doing?
Thanks?
