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Potterton Promax 15HE not modulating

Discussion in 'Plumbing and Central Heating' started by bikeman123, 11 Mar 2011.

  1. bikeman123

    bikeman123

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    My Potterton Promax 15HE not modulating - the burner is always at max and never modulates down.

    Had several engineers scratching their heads. Eventually found a guy who'd do it for a fixed price. He has changed the flow thermister and both the control and ignition pcbs but no fix yet.

    From my own research I understand that the gas valve controls modulation by varying gas pressure under the control of the control pcb. Is this true for this boiler?

    Can the GV be changed without interferring with the gas supply?

    Can it be adjusted?

    What else might cause this problem?

    Thanks
     
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  3. Boilerman2

    Boilerman2

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    THe Promax uses a Honeywell Modureg valve which modulates the gas pressure up & down using a reference voltage from the boiler PCB it is not possible to change this without disturbing gas related parts and a RGI would be required to do this work as the valve would need careful setting up ...Are you sure that the exisitng vale is correctly set? get the RGI to check if he pulls one of the wires off of the modureg coil the flame should drop to low fire, if it doesn't then either the valve is incorrectly set up or it is shot ;)

    THIS IS NOT A DIY JOB A GAS ENGINEER MUST BE EMPLOYED!
     
  4. shawd

    shawd

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    Gas valve not adjustable, modulates from pcb, I would check standing and working pressures.
     
  5. shawd

    shawd

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    A RGI is required to carry out this work.
     
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  7. bikeman123

    bikeman123

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    Helpful thanks.
     
  8. bikeman123

    bikeman123

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    Had a newteam rgi out this afternoon - came highly recommended by neighbours but he didn't run any tests, didn't check gas pressure and simply tried 3 pcbs in turn - all the same.
    Then removed a couple of the pcb jumpers and charged me £120 for a new board.
    I suspect the jumpers he removed just altered the output so it now runs less heat but still doesn't modulate. Probably wont have enough heat now for a v cold winter.
    I think I've been ripped off and I am thoroughly ****ed off.
     
  9. shawd

    shawd

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    Sounds a bit strange,,,, who is newteam , did you check to see his gas safe card.
     
  10. bikeman123

    bikeman123

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    Sorry I meant HeatTeam. Anyway I am pleased to say that it is now fixed. The burner modulates down as the flow water heats up and actually turns off when the flow reaches temp - something I was told wouldn't happen. I am sure it wil now be much more economical.

    Fingers crossed all will be ok - it has something of a reputation for unreliability!
     
  11. DIYnot Local

    DIYnot Local

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