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intergas rapid control panel status, cold water tap on

Discussion in 'Plumbing and Central Heating' started by Mr Chibs, 18 Apr 2019.

  1. Mr Chibs

    Mr Chibs

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    Wonder if you guys can tell me if this is right/wrong.

    I've recently had a 32kw rapid plus commissioned, all seems to be working well.
    But I've noticed that when the cold tap/toilet is used, the boiler status number changes and you can hear the boiler internals working... (pump/igniter?)

    The status light goes from 1, 3, 4, 5, 6 then finished on 5, this is within a 30 seconds.

    I hadn't expected the above when using cold water, it's like the boiler is sensing the change in pressure.

    tia
     
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  3. bernardgreen

    bernardgreen

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    Is that any cold tap or just the cold tap next to the toilet ?

    Maybe the plumber has connected the toilet and that cold tap to the hot water pipe instead of the cold water pipe.
     
  4. muggles

    muggles

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    It is indeed sensing a change in pressure - you need a single check valve fitting on the cold inlet to the boiler
     
  5. bernardgreen

    bernardgreen

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    Are you serious ?

    Are you really saying that a change in pressure in the water supply can cause the boiler to fire up ?.
     
  6. Mr Chibs

    Mr Chibs

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    I'll check the cold tap upstairs Cheers.

    I'd only noticed this when changing the downstairs loo... the boiler is in same room.

    I read that the intergas boilers are slightly different inside than most other boilers and wondered if this was normal
     
  7. bernardgreen

    bernardgreen

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    Is that a good idea ?

    If a check valve was fitted then what provision would there be for the expansion of the water in the DHW coil in the heat exchanger when the boiler fires up for Central Heating ?
     
  8. muggles

    muggles

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    Not only is it a good idea, it is recommend by several boiler manufacturers. No provision for expansion is required, although a mini expansion vessel can of course be fitted if desired
     
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  9. Razor900

    Razor900

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    If it's a new install and they took the hot water cylinder out there's probably some air trapped inthe old pipework. If you bleed it out the problem will go away.

    It's quite straightforward @bernardgreen if there is air trapped it is compressed by the pressure from the incoming main when there is no demand. When a cold tap is run the pressure drops in the pipework and the air expands pushing water back through the flow turbine. Unlike earlier models that used an on/off switch the Hall effect sensor in the turbine doesn't realise it's going the wrong way and tried to fire the boiler.

    Unusual to actually get as far as 6 though, usually it only gets as far as 3
     
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  11. Gasguru

    Gasguru

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    Sort out the dodgy pipework..probably a redundant dead leg somewhere thats been capped off or...
    you've got a length of pipe ready to feed a washing machine etc that has trapped air that needs bleeding out.
     
  12. bernardgreen

    bernardgreen

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    if desired, or if found necessary. Where in the pipe work would you fit it ? Before or after the flow sensor ?

    Maybe the control algorithm should be improved such that it counts more impulses from the sensor before deciding to fire up the boiler. Or fit a bi-phase sensor such the the control algorithm can determine the direct of flow through the sensor.
     
  13. dilalio

    dilalio

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    No Bernard. Best practice is to not leave long dead legs and bleed air from the lines.
     
  14. bernardgreen

    bernardgreen

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    I do not dispute that. But the boiler should not fire up on reversed flow no matter what causes the reverse flow.
     
  15. Razor900

    Razor900

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    Two points in response to that...

    Firstly if the job was done properly and any deadlegs removed which they should be in accordance with the water regs the problem wouldn't exist.

    And if the control algorithm was modified people just like your good self would be able to crow that it took even longer to get hot water from a combi.

    And that's exactly your problem Bernie. I explained what was happening for you but you're too busy bring a dick to learn anything.
     
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  16. bernardgreen

    bernardgreen

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    Calling a person who has a different opinion to your opinion does not make your opinion any more valid.

    I had already realised that the boiler was responding to flow before you confirmed that was the cause,

    Counting a few more pulses would further delay the start of heating the hot water but the extra delay before firing would be short in comparison to the time it takes for heat to get through the heat exchanger from flame to water.

    Muggles suggested maybe fitting a mini expansion vessel

    In hydraulic terms a dead leg with trapped air is the same as an expansion vessel with trapped gas ( nitrogen or air ) except that the expansion vessel has a membrane separating water from gas.
     
  17. dilalio

    dilalio

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    And doesn't pose a legionella risk.
     
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