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Very Frustrating Boiler System Problem

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  • billtwocase
    billtwocase Member Posts: 2,385
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    I would pull that side jacket off and look for either a coil, or blank plate. That is either a PFO-3T, or a PFO-4. This was before Dunkirk bought them and began their downward spiral
  • Zman
    Zman Member Posts: 7,569
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    @Kcopp,
    That was a really good call.
    With the check valve installed, the zone piping was effectively isolated from the expansion tank when the call for heat went away (zone valves closed).
    The cooling water in those pipes contracted dropping the pressure. When the pressure regulating valve saw this drop in pressure, it would add water. This cycle would eventually cause the system pressure to get high enough to make the expansion tank ineffective and pop the the PRV on the boiler.
    When the fill valve was isolated the pressure was probably sub atmospheric on the upper floor resulting in air getting in and the associated racket when the valve opened and everything equalized.
    Nice...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • rick25s
    rick25s Member Posts: 49
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    Zman said:

    @Kcopp,
    That was a really good call.
    With the check valve installed, the zone piping was effectively isolated from the expansion tank when the call for heat went away (zone valves closed).
    The cooling water in those pipes contracted dropping the pressure. When the pressure regulating valve saw this drop in pressure, it would add water. This cycle would eventually cause the system pressure to get high enough to make the expansion tank ineffective and pop the the PRV on the boiler.
    When the fill valve was isolated the pressure was probably sub atmospheric on the upper floor resulting in air getting in and the associated racket when the valve opened and everything equalized.
    Nice...

    That makes complete sense.
  • kcopp
    kcopp Member Posts: 4,432
    edited January 2016
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    I saw it on a job years ago when they first started w/ IFC circulators. Another contractor was having a real problem w/ the relief valve blowing off.... Since then I always yank them out in ZV set ups. I can be taught!
    I noticed the sticker was still on the 15-58.
    Glad it helped and glad it was me helping out instead of me asking for help as I have done many, many times here!
    rick25s
  • billtwocase
    billtwocase Member Posts: 2,385
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    I refuse to use IFC pumps. This and other problems are not too far down the road. They still make flowchecks. Tack the price on the job, and be done with it

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