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Pump not circulating through auto-bypass valve

  • 26-09-2011 12:33PM
    #1
    MrThrifty
    Registered Users, Registered Users 2 Posts: 491 ✭✭


    Feck... another problem! Was setting up a frost and pipe stat with the heating system in anticipation of another bad winter and noticed that the water is not circulating through the auto-bypass valve even when it is fully open (~0.1 bar). I've played around for a bit and found the following:

    - If the pump is on and a zone valve is open, the water will start circulating through the auto-bypass valve when it is opened a bit. Then, if the zone valve is closed, it will continue circulating through the auto-bypass valve. All as expected really, but...

    - If all zone valves are closed and the auto-bypass valve opened (even fully), the pump does not start when power is applied. As in, there is no rotation at all when you remove the bleed screw, like it's jammed. It's possible that it gets hot during this time, not sure though - did not want to leave it switched on!

    So, does the problem sound like it's with the pump (Grundfos) or the auto-bypass valve (Myson)?!

    Not sure now if the auto-bypass setup ever actually worked. But the system has had a bit of a hard life (being partially drained for months, no pump over-run, having pump running continuously for weeks at one stage, pump not being primed a few times and getting a bit hot, etc., etc.!!).


Comments

  • #2
    JohnnieK
    Registered Users, Registered Users 2 Posts: 2,526 ✭✭✭JohnnieK


    It sounds like you have no pump over run on your system, when the last zone valve closes the power shuts down and that's that. Is it oil or gas that you have and is the pump wired directly into the boiler?


  • #3
    MrThrifty
    Registered Users, Registered Users 2 Posts: 491 ✭✭MrThrifty


    It's an oil boiler but I should have explained that the programmer is removed and I'm turning on the pump by connecting it directly to the mains electricity supply. So power is definitely getting to pump, but for some reason it won't start unless a zone valve is opened. It's a Grunfos Selectric 25-50 with the usual 3 speed selection option. Just trying to establish without replacing stuff if the problem is a faulty ABV or the pump itself.


  • #4
    MrThrifty
    Registered Users, Registered Users 2 Posts: 491 ✭✭MrThrifty


    Aghhh! I'm a muppet! Just read your reply again - in the mess of wires I forgot that the pump was bloody well wired through the zone valve sensor switches. Doh! Cringe... :o

    So there never was a problem (with the equipment)!

    Thanks for response.


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