I was cleaning my burner/boiler (Dunkirk 3e1.00 Beckett AFG burner, hydronic heating and house hot water) and noticed "working water psi" is 30 and realized the gauge always read 40 psi.
So I thought I should drain off some water. As soon as I did the Taco 329-3 PRV valve let more water in and the pressure went back to 40. Repeated the drain and the same thing happened so I started getting concerned and shut off the upstream feed valve and drained off the water again. Is the PRV valve faulty ?
Pressure went down to 25 psi before draining turned to a trickle. Shouldn't it go down to 0 psi when I drained off the water ?
I was also surprised that if my pressure was so high, why wasn't my pressure relief valve opening ? Checked it and it seemed to be stuck. Lots of corrosion/mineral/green deposit built up around it. I actually got it open, and wouldn't completely close back up again.
I didn't want to refill the boiler while it was still hot so I left the valve closed/pressure at 25. But since there was no water in it I didn't want to run it. So the burner is off and the water is mostly drained...or is it ? What about the water supply for heating the house hot water ?
I wanted to turn the burner on so my wife could take a hot shower, but refrained out of concern for having draining the heating. WOuld it be ok to run it if the heating is drained, but the house hot water supply is still feeding it ?
My next steps will be to get a new pressure relief valve and expansion tank, refill it and turn it back on.
Any other suggestions ?
So
If you know your gauge reading is accurate , you have an issue with you pressure reducing valve. Your relief valve not opening is a symptom not the cause, change that , tap on the gauge with adding water to get accurate reading, do that once you change the relief valve so you can match it with the gauge , if it doesn't open after adding more than 30 psi, change the gauge , but check your pressure reducing valve, you should have a tap on the supply line added after the reducing valve to attach a gauge to get actual reading of water pressure.
If your boiler is what gives you hot water, it is absolutely not acceptable to try and run a boiler if it isn't full of water and bled of air. You could have a faulty gauge. A lot of boiler gauges don't work well after some time. Also, I don't know the highest point your system requires water. Knowing this is how we figure out how much pressure should be in the system. There could also be issues in how the system was designed that I can't see.