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Trouble Refilling Boiler System - Weil Mclain Ultra 80 w/ HWH

Ringo311 Member Posts: 22
I drained my boiler system yesterday to work on some plumbing, which I've done before, but I'm having trouble with refilling the system this time around.

I filled up the lines and the boiler and everything before turning on the boiler and opened up the baseboard upstairs to make sure water got into the lines everywhere. But when I turned the boiler on I ran into several issues:

Firstly, I keep getting locked out by cold return temperatures. "Return >59d from supply". After leaving it on all night the temperatures started working their way up to 130's and 140's which i was pretty happy about. Today though, I ended up with another lockout error - "low water shutoff" and my temperatures dropped substantially.

Here's where I'm confused and hopefully someone can shed some light on this: the waterline that feeds the system was constantly pumping water into the boiler system even after the lines were full, which is introducing cold water into the system all the time. And at the same time the pressure relief valve right at the boiler is almost constantly spitting water out. I cant remember this every happening - I just assumed that the cold water being heated up inside the boiler is resulting in a ton of pressure so I let it go.

The problem is I cant seem to get the system to neutralize and heat up fully without releasing water through the pressure relief valve. Since there is a constant flow of cold water from the outside, I"m not sure its ever going to get there. Can any help me get this situated?


  • Ringo311
    Ringo311 Member Posts: 22

    So my boiler is up to temperature and we have heat. My system pressure was around 16-17 and the pressure relief valve was still spitting out water so I fiddled with the handle and it stopped. There appears to be a tiny bit of water being added to the system from the water intake but everything seems to be performing normal and the system pressure is 13-14. Hoping this keeps up.

    Is it possible the pressure relief valve was getting stuck open or is broken?  
  • Ironman
    Ironman Member Posts: 7,379
    It Is

    You need to change it.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
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