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Boiler Pressure Dropping

  • 03-04-2023 10:54pm
    Registered Users Posts: 222 ✭✭

    Hi guys, I recently renovated my home and the pressure in the new boiler is dropping every month or so. I presume this means there is a leak somewhere in the system and I'm wondering if there is any way to locate this without tearing the house apart?

    Post edited by DOCARCH on


  • Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 17,677 Mod ✭✭✭✭DOCARCH

    Mod Note: May be more appropriate for plumbing forum.

  • Registered Users Posts: 5,359 ✭✭✭DublinDilbert

    What was replaced on the renovation?

    Does it drop gradually or seem ok for weeks then drop in one go?

    On a recent renovation I had an issue with boiler pressure dropping occasionally, it could be ok for a few weeks, then it would drop. I traced it down to the water not having any path, when the zone valves turn off, so seemed to be venting off via the 3 bar release valve. There was no automatic bypass fitted, so i just opened the flow the hot cylinder (not zoned). Since I increased the flow to the hot cylinder, the pressure hasn't dropped in 3 months (or so).

    Find the pipe from the 3 bar pressure release valve and place a balloon or rubber glove on it. If anything vents off, this will fill with water.

  • Registered Users Posts: 2,569 ✭✭✭Yellow_Fern

    I had the same thing. I found it as there was tiny streak of rust on a rad's blanking plug. That was enough to cause pressure loss.

  • Registered Users Posts: 222 ✭✭BalboBiggins

    Thanks lads, it's fine for three or four weeks, then drops in one go. I will review your suggestions and hopefully that might solve it.

  • Registered Users Posts: 2,569 ✭✭✭Yellow_Fern

    That timing was just like mine. Def check your rads and all joints for corrosion where a leak might occur

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