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pressure paradox?

Bob HarperBob Harper Member Posts: 728
I must be suffering from cerebral flatulence:

WM hot water boiler CG-6-PIDN 175mbh NG> found the Tricator gauge reading about 45 psi static cold but the PRV is not discharging (rated 30psi). Hose thread pressure gauge at boiler drain reads 16 psi. Two story house. Steel expansion tank drained and re-tested-same.

Since it was an old relief valve, I changed it along with a brand new tricator gauge. Re-installed and still reading twice as much at tricator as at drain cock.



  • nicholas bonham-carternicholas bonham-carter Member Posts: 6,385
    Parallel universe?

    Can you move the drain gauge to the tridicator port, and recheck?--NBC
  • Bob HarperBob Harper Member Posts: 728
    At least someone responded

    I thought of rigging another pressure gauge at that port but didn't have one with me. Will return Monday and test.

    Thanks for the reply NBC-one out of 83 looks.
  • ZmanZman Member Posts: 3,196
    Another guage??


    That is quite a puzzle. I assume there is a clear path from the drain gauge to triadicator?

    Since your gauge and 2 pressure reliefs say it is less than thirty. Try another triadicator or as suggested move your gauge.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • LarryCLarryC Member Posts: 331
    Is the trigauge port a thermocouple well?

    I know this a stupid question, but perhaps the original installer of the old trigauge used a port that is not pressurized by system pressure.  The temperature would still read and if there is trapped water in the well, the pressure will change but not reflect actual system pressure.
  • PlumdogPlumdog Member Posts: 873
    Don't trust your gauge too much!

    I keep a couple gauges with hose adapters in my bag at all times.The tridicators are only accurate for about 2 days after installed new. The very old ones seem to last forever, while the newest ones are crap and cannot be trusted. Plus they are way overpriced. So I check with one gauge, and if it doesn't correlate, I check with another. I just use cheap throw-away variety gauges because they freeze and get broken, etc. But never trust just one gauge. Sometimes tridicator gauges will be accurate enough, but read 10 or 15 pounds more than actual pressure. It is not possible for the pressure to be that much different in two locations!
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