I have a 3 year old Munchkin T80 boiler. About a half dozen times now it's had a PR0 error. System pressure has always been fine. I cycle power to the boiler and the error comes right back. I disconnect and reconnect the wires to the switch and it will work fine for days to months. Any suggestions?
Air in the system will also give this code, as the pressure switch reacts differently to air than water. What type of expansion tank do you have, diaphragm or old school compression?
I worked on a 140 M with the same pro signal. First I jumped the switch to make sure it would fire and it did. I called tech and they told me to tap it a bit with the but of a screwdriver in the jumped condition with the boiler running. The thought was trapped air in the switch after about 30 mins of running to heat up the tank I reconnected and the PRO appeared. Right before I was about to change it out, I boosted the water pressure a bit to 18 lbs. flipped the switch the unit pre purged and went into standby mode with no error signal. Two things I know for sure 1. is that the PRV valve I use has an indicator on it that isn't always acurate and 2 sometimes boiler guages are not quite acurate. Try turning up the water pressure a bit to see if that helps. JB
Thanks for the information. T80's been running fine for a week. In response to RPA Guest, I've got a diaphragm expansion tank. My pressure gauge typically reads between 17 and 19 lbs. If it happens again, I'll turn up the pressure a little and see if that fixes it.
I received a no heat call with a pro signal. This is the 3rd time with the same boiler. The pressure switch works sometimes and not other times. I pulled the old pressure switch to change out with a new one and what did I find? Thread tape that was bunched up and closing off the hole. I removed blockage and reinstalled, so far so good. JB
