cold fill boiler preasure

PLUMBARIS

Dosen't make any diff. The tri-indicators and prv aren't accurate to know

mark schofield

cold fill boiler pressure

Once the system preasure in a closed loop hydronic system has been determined in relation to the height of the highest baseboard above the boiler and adding 5 psi, is the preasure set at the cold fill temperature (60 deg. f) or at the minimum operating temperature of the boiler (120 deg. f). In my particular case the boiler will be kept at a minimum of 120 deg year round (not a cold start) so would the 10 - 12- psi be determined from the low limit year round setting of 120? thanks, Mark S.

Brad White_191

Cold fill pressure is the standard.

Most systems are filled when cold ("if they have no water in them, they cannot get hot"

The pressure will rise when heated of course, but not much if your expansion tank is sized properly and you are only running 120F.

120 year round? Great. Lots of radiation I bet. But I also bet you have room for outdoor reset.

mark schofield

Thanks Brad. The 120 is the low limit setting on the honeywell aquastat. The high limit is set at 190. I do have outdoor reset (Honeywell AQ475) which does quite well. At 120 the preasure is about 12 psi. When it's cold (10 deg outside)and the water temp is around 180 with the circulator running, the psi on the supply to the sytem after the pump (pumping away) is around 23.

Brad White_203

Very good, Mark

Your system sounds fine. I often see a little less rise from cold to hot (yours is about double; I like to see not more than a 50% rise but this is entirely arbitrary). You are still way below the 30 PSI relief valve limit. I always like a 5 PSI margin (not over 25 PSI at maximum operating temperature), so you are OK in my opinion.

Thanks for clarifying the ODR and that the 120 is a base level. Is that enough to give you boiler protection? That is my only concern.

Cheers!

Brad

Mark Eatherton

I HOPE you have a condensing boiler..

Because if you don't have one, you will... and you may not want one ;-(

I use the 90% rule for maximum pressure. If it has a 30 PSI relief valve, then maximum operating pressure would be 27 PSI (30 times .9 = 27)

I think you're OK, but best to mark the gages and have the HO keep an occasional eye on it.

ME

mark schofield

Mark and Brad; thanks for the answers. I raised the low limit on the aquastat up to 130. I put the boiler (WM-WTGO3) in 3 seasons ago and have it professionally tuned (digitally) yearly by my oil company. No soot build up or sticking to the fire side so far. I brush it out myself 6 months after the tuneup. Still very clean after 3 years. I put the ODR in 2 years ago and so far, when watching the temp supply gage, it's doing just what it should. Thanks again. Mark S.