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Boiler not switching on, pump not running, no hot water - please help?

Discussion in 'Plumbing and Central Heating' started by HazelFlorist, 8 Aug 2019.

  1. HazelFlorist

    HazelFlorist

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    I have a traditional gravity, pumped CH system, tank in the loft, cylinder in the airing cupboard, digital thermostat in the hall way, electronic timer in the kitchen, Greenstar Ri boiler in the garage in a two story house - all fairly typical.

    Boiler is about 5 years old, as is the pump and honeywell - all replaced together.

    Suddenly, the there is no hot water - my limited diagnosis so far...

    The boiler and central heating pump and honeywell will not fire up or operate and run under any auto or manual command.

    The thermostat in the hall has power and appears to be functional
    The timer in the kitchen has power and appears to be functional
    The thermostat on the water cylinder is set to 70 degrees and altering it makes no difference
    Altering the hallway stat makes no difference and I can see the symbol that calls for heat illuminated
    Altering the thermostat on the boiler makes no difference
    The boiler solid blue light is permanently illuminated and is not flashing
    There is no green 'pilot light' illumination on the boiler (little flame symbol) I know they don't have a traditional pilot light and this is just a burner operation LED
    I've tried to manually adjust the Honeywell 3 way valve lever but it appears lifeless and doesn't automatically revert to a previous position under it's own power as I've witness previously when I've tried to diagnose other issues years ago - the valve doesn't appear to have any power to it
    The central heating pump does not run at all in any condition or command

    So, in summary, everything seems to be functional except the pump, honeywell valve and as a result(?) the boiler will not ignite, fire up and do it's job.

    That is about the extent of my diagnosis skills and I'm not hugely familiar with the protocols of each part of the system from an electrical perspective. No circuit breakers are blown on my distribution panel.

    The immersion switches on and lights up, but obviously not a permanent solution beyond having a shower today.

    Any clues where I go from here - why is the boiler not firing up and the pump not running and the 3 way valve just as lifeless?

    Really appreciate any further checks, tests and diagnosis tips.

    Thanks in advance.
     
  2. Harry Bloomfield

    Harry Bloomfield

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    Usually - the clock feeds the stats, then the stats feed the valve, the valve then controls the boiler and the boiler then controls the pump.

    Difficult to diagnose at a distance, but it sounds like a valve (actuator) issue. Have you tried powering it down and back up?
    Have you tried taking the actuator head of the valve and made sure the valve is free to turn, it should be just about possible to turn it with your bare fingers?
     
  3. HazelFlorist

    HazelFlorist

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    Valve actuator issue - the honeywell?

    When powering it down, do you mean the boiler? I've switched the boiler on and off a few times and reset it, but it doesn't make any difference. I can hear a little click sound when the boiler switches on. I've not looked at the honeywell yet - last time I tried to get the cover off I wouldn't reveal what I wanted to see from memory. The lever feels free and 'loose' and doesn't feel like it's rotating the valve. I'l try again to get inside it tonight after work.
     
  4. Harry Bloomfield

    Harry Bloomfield

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    I was suggesting turning the whole lot off at the mains, then back on.

    I read your '3 way valve' as it being what is called a 3-port valve, one input port, two output ports. Yes, the Honeywell. Get the model number from it.

    The actuator is the electrical part of the valve, the valve head. They fail more frequently than the actual water flow control valve and they can be bought separately from the valve. They are usually attached to the valve via two screws. The manual lever being completely free also suggests it is probably the valve actuator which has jammed.

    My own actuator would regularly fail and need replacement - often enough, that I would keep a spare to hand ready to fit. They work under tremendous strain, a motor fighting a strong spring. I have now changed to a completely different design, where no springs are involved :)
     
  5. stem

    stem

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    That can be a good sign. It should be loose and floppy if the system is calling for central heating and the valve has been wound to the heating position by its motor, meaning that the lever does nothing.

    It's fairly easy to test to see if it's sticking. Try turning off the mains power to the heating system completely at the fused spur, not just the programmer. If there is resistance on the lever now, the valve has returned to its rest position (hot water).

    The odd part is, that when heating is required, the boiler is switched 'on' by the motorised valve. But when hot water is required, it is switched 'on' by the hot water cylinder thermostat. What are the odds of both failing together? It's possible I guess, but pretty unlikely. Therefore, I would suspect a boiler fault, especially as the Greenstar Ri boiler has the pump wired to it as it is responsible for controlling it directly.

    However. as @Harry Bloomfield says, it's difficult to diagnose at a distance, it probably really needs someone to visit with suitable test equipment that can trace the control signals through the system to see how far they get.
     
    Last edited: 8 Aug 2019
  6. martyndc88

    martyndc88

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    It It were a boiler fault I'd expect the blue light on the boiler to be flashing giving a fault code.
    Is your timer Honeywell ?
    As above kill the power and see if your motorised valve motors back and has resistance
     
  7. HazelFlorist

    HazelFlorist

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    Thanks everyone for your replies so far. (It's a Drayton Tempus Six Timer)

    Latest findings... (with all stats turned up to max on boiler, cylinder, room stat and timer set to request heating and hot water)

    I removed the cover of the 3 port Honeywell valve (no model name or number on it anywhere, or the case) and as I did so, the pump suddenly started up! Hooray I thought...

    I ran down to the boiler expecting it to be burning but it was silent and dormant as before, with it's steady blue light and no green 'pilot' light. Damn.

    I ran back upstairs to find the pump had stopped, so explored the valve head. I noticed two micro switches visible on the circuit board - I gentle prodded the top one and nothing happened. When I prodded the bottom one it clicked and pump burst into life.... but not the boiler. And then shut off after a couple of minutes.

    Tried again, same thing - pump runs for 2 mins, then shuts off. Boiler doesn't respond.

    I then turned all power off as suggested and tried the valve lever - still floppy and loose with no resistance in either direction - same when the pump was running after prodding the micro-switch - floppy lever.

    After having the immersion heater on for a while today, resulting in warm water coming from the taps, I expected that with the heating (rads) being on demand from the timer and stats, that pretty quickly the warm water from the cylinder would begin to circulate to the rads whilst the pump was temporarily running - nothing, all pipes leading from the cylinder are stone cold, even after the pump has been running for a couple of mins before auto shut down. The only warm pipe from the cyl is the one to the taps.

    Am I correct to deduce the 3 port valve is stuck closed, at least from the rads flow perspective? If so, does this impact the boiler not coming on, even with all stats set to max on the cyl and boiler?

    Given the above, what is my next step to get the boiler to wake up and burn some gas?

    Why is the pump switching off after two mins? (it did this before and after use of the immersion heater, so it's not like the boiler is receiving piping hot water and thinking it doesn't need to do anything, if that's how it's designed?)

    I really appreciate the help so far.

    What can I do / test next?

    Many thanks.
     
  8. HazelFlorist

    HazelFlorist

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    Quick update - found the valve number - V4073A1039

    Managed to remove the head from the valve and I can manually adust the vlave by hand (it only turns about 20 degrees, normal?)

    When I turn the valve (with the pump running after prodding the micro switch) there is a clunk in the pipes (fluid hammer effect?) and in one position the pump changes sound as it's load changes, when it clunks to the other position, I hear water flow..... but..... no heat in any of the pipes coming two and from the hearing coil within the cylinder. Only area of heat is the flow to the taps from the cyl.

    Please correct my flawed logic, but if we know the cyl contains hot water (immersion + hot tap pipes) and if the pump is flowing, then surely if I am able to manually force the pump to work by activating the micro switch, then if I manipulate the honeywell valve in either position, one of them should see heat in the pipe that feeds the rad? Yet it doesn't and I can't fathom why.

    Hot water in tank - yes.
    Pump running - yes.
    Valve free and controlled manually - yes
    Try in both positions including a half way position - nothing - no heat in any pipe.

    What the actual....?
     
  9. Harry Bloomfield

    Harry Bloomfield

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    I have no experience of that actuator/valve, but its a five wire, spring return. Its a V4073A 1039. There are more details here, including a wiring diagam - https://www.honeywelluk.com/Documents/Installation-Guide/pdf/1083.pdf

    With no power applied, it should return to its default HW only position and should need some slight effort on the manual lever, against the spring - which I think you are saying the lever has no resistance?

    The 20 degree turn doesn't sound right either, but perhaps others could comment on that? I would expect it to be reasonably free to be turned 360 deg.

    Your boiler not firing, could be a fault on the boiler itself, or more likely you need to give it more time. Mine takes around a couple of minutes from call for heat, to actually igniting. The modern way is for the boiler to cause the pump to run, rather than the valve, so that the pump can continue to run to remove the residual heat in the boiler, after the burn has ended.
     
  10. terryplumb

    terryplumb

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    If your boiler is not igniting ( for whatever reason ) the pipes going to / coming from the heating coil in your cylinder will not get hot. The pump is just pushing cold water through them. The fact that your immersion heater has heated the domestic hot water within the cylinder is irrelevant. You need to engage a GSR engineer to investigate and establish what's at fault. Its really not wise for you to be "prodding around " where mains voltages are present.
     
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  11. dilalio

    dilalio

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    Get a man in and save your keypad :)

    Edit.... Man or person :rolleyes:
     
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  12. Harry Bloomfield

    Harry Bloomfield

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    Where is the learning experience in that?
     
  13. dilalio

    dilalio

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    Learn when you don't need a sh¡t/bath/shower/wash/drink/warmth etc etc...
     
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  14. stem

    stem

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    The second microswitch that operates when the valve is at maximum travel, is responsible for operating the boiler when central heating is required, but there is still something else wrong. You originally said that the fault came to light because you had "no hot water" and the boiler is switched on by the hot water cylinder thermostat when the hot water is required. The motorised valve could be in any position, or even disconnected altogether but the hot water cylinder thermostat would still fire up the boiler.
     
  15. HazelFlorist

    HazelFlorist

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    Thanks for the replies everyone - it's now fixed and working correctly, but rather frustratingly, I cannot pinpoint exactly what was wrong, other than by fiddling with the honey well and manually moving the clock work mechanism against the springs whilst also manipulating the physical valve and putting it all back together it now works. I wish I knew what the problem was.
     
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