Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Pigtail removal and relief valve checking

jweob Member Posts: 14
I'm starting up my boiler for the winter and would like to check my pigtail and relief valve. I am paranoid that one or both might be plugged (no particular reason other than I'm a worrier, and the boiler looks like a giant steam-powered bomb if I stare at it for too long). I'm hoping to get some advice on both of these points.

1) The pigtail is connected to a tee which branches out to two pressuretrols and a pressure gauge (see picture with operating pressuretrol temporarily uncovered). Is there a smart way I can unscrew the pigtail without being blocked by the pressuretrol wires? I understand that it can be difficult to unblock pigtails so I have a spare ready.

2) My pressure relief valve comes out of the top of my boiler. The manual says that this should be tested monthly as follows "With the system at operating pressure, lift and hold the test lever fully open for at least 5 seconds to flush the valve seat free of sediment and debris." What can I expect when I open the lever, given that my operating pressuretrol has min pressure 0.5 psi and 1 psi differential - will it be steam or boiling water? Is it safe to do at arms length with gloved hands or do I need to take other precautions? I've seen other comments saying that if you test the pressure relief valve then about 50% of the time it will then start to leak afterwards - how do I reconcile this with the instruction to test monthly?

Thank you!


  • 109A_5
    109A_5 Member Posts: 1,387
    edited October 2022
    Hello @jweob,

    First time through the power to the boiler should be shut off, the wires removed from one of the pressuretrols and remove the pressuretrol from the pipe and blow through the pipe or see if water will flush through the pigtail.

    On the lower pressuretrol I would add a union or add a 'Tee' and a plug and other needed fittings so annual maintenance is easy. If a 'Tee', and plug is used, offset the lower pressuretrol so that just removing a plug gives proper straight on access to the pigtail. A flexible cable like the outer springy part of a bicycle brake cable or a lawn mower throttle cable can act as a small snake to keep the pigtail open with minimal further effort.

    I would make sure water is in the pigtail when done.

    Relief valve, just don't be near the end of the pipe which it looks like it is near the floor. Open slowly, wet steam and some dripping condensate should come out. If it leaks replace it.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • jweob
    jweob Member Posts: 14
    Genius! You’ve saved me so much time thank you!
  • jweob
    jweob Member Posts: 14
    A further update on this - I used the advice to remove the pressuretrol and found all the piping was totally filled with gunk. I did have to remove the pigtail in the end but I have reassembled it with easy access for future cleaning
  • 860
    860 Member Posts: 4
    You did right.
    Here’s one recently that I had found also where everything was on its way to being clogged. 

  • Long Beach Ed
    Long Beach Ed Member Posts: 1,212
    edited November 2022
    Looks to me like a row of steam controls flooded in water.