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Pressure issue - Grant Oil Boiler

  • 17-03-2021 03:22PM
    #1
    Cakes and Ale
    Registered Users, Registered Users 2 Posts: 203 ✭✭


    Having some problems with loss of pressure in a Grant boiler. The problem is that it is random, sometimes slow, sometimes very fast. Had someone out to look at it the other day; they drained system, re-pressurised expansion vessel, couldn't spot any leak and were doubtful there was any because there was no drop in pressure at all while they were there. Pressure was fine until about a day later, there was no drop while it was on for HW and downstairs heating (have 3 zones), but today after heat was on in the morning for an hour, and then turned off for a few hours, I came back this afternoon to find pressure at 0.

    They did suggest that maybe the expansion vessel might need to be replaced - there was water in it when they looked at it - is this the most likely scenario and is there any way to check this before getting someone in again?


Comments

  • #2
    Wearb
    Moderators, Home & Garden Moderators Posts: 6,707 Mod ✭✭✭✭Wearb


    Cakes and Ale wrote: »
    Having some problems with loss of pressure in a Grant boiler. The problem is that it is random, sometimes slow, sometimes very fast. Had someone out to look at it the other day; they drained system, re-pressurised expansion vessel, couldn't spot any leak and were doubtful there was any because there was no drop in pressure at all while they were there. Pressure was fine until about a day later, there was no drop while it was on for HW and downstairs heating (have 3 zones), but today after heat was on in the morning for an hour, and then turned off for a few hours, I came back this afternoon to find pressure at 0.

    They did suggest that maybe the expansion vessel might need to be replaced - there was water in it when they looked at it - is this the most likely scenario and is there any way to check this before getting someone in again?

    If its a problem with the expansion vessel you'll have water coming from pressure relief valve when system is heating up.


  • #3
    John.G
    Registered Users, Registered Users 2 Posts: 3,916 ✭✭✭John.G


    As a quick check just press the the schrader (tyre type) valve with your finger nail, if no pressure with no pressure on the water side, pump up the air side to 1 bar and then open the filling loop to give 1.3 bar then remove filling loop. If water comes out the air side the E.vessel is kaput.


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