Hot water but no heating.

Discussion in 'Engineers' Talk' started by billfromarran, Dec 26, 2019.

  1. billfromarran

    billfromarran Active Member

    Hello. Boiler is a Worcester Greenstar heatslave 12/18 (oil )running hot water and 6 radiators.
    Serviced early this year, and has not had any issues, until now.
    Hot water is working but heating is not .Room stat is OK, when I turn it up and down there is a clicking on ad off in the boiler cabinet .
    The pressure is within normal range, all radiators have been bled and the boiler will sometimes run for about 2 minutes and then switch off.No heat comes through to the rads. The lockout indicator light does not come on. This has happened suddenly, it was working fine up until yesterday. Any advice much appreciated.
    PS of course, being today, every heating bloke has the phone switched off! And why not?
     
    Last edited: Dec 26, 2019
  2. Mike58

    Mike58 Active Member

    Is there a three port valve? If so, it may be stuck or not working.
     
  3. billfromarran

    billfromarran Active Member

    I can see the lever on top of theDrayton diverter valve moving when I turn the room stat up and down, so it would appear to be operating ok. Thanks.

    Got to go out for a short while, so will be back later.
     
  4. Mike58

    Mike58 Active Member

    Level may move but is the actual valve? Can you take the head off and move manually?
     
  5. billfromarran

    billfromarran Active Member

    I can get the cover off the diverter valve, but the head is very awkward to access, I would have to shift the expansion vessel.
    When the Room stat is set to "on" should I be able to feel the pump working. I tried putting my hand on it, and there is no vibration. Would it come on straightaway,or cut in after a set time?
     
  6. Joe the Plumber

    Joe the Plumber Well-Known Member

    If there's hot water coming into the valve, see if it's going out both ways when your controller is calling for heat and hot water. If it's only going to the hot water side, the valve is likely to be the problem.
     
  7. billfromarran

    billfromarran Active Member

    Hi Joe, I can only feel one outlet of the valve,the top one,and it is hot .I can't get my fingers in far enough to feel the other side of the "T" .It goes down into an insulated tank.
     
  8. billfromarran

    billfromarran Active Member

    I am guessing that this is the hot water storage tank?
     
  9. Joe the Plumber

    Joe the Plumber Well-Known Member

    We could really do with a photo of the valve please Bill.

    If it's a three port valve, the hot water from the boiler usually comes in from the bottom of the 'T' (opposite the actuator head) and goes one way off to the hot water cylinder to heat your tap water and the other way into the central heating pipework.

    They usually fail so you only get hot water, but have a lever on the body that allows you to open the CH side. The water heating the cylinder then also goes round through the radiators, albeit without any automatic control.

    If it is the valve, the one good thing is it's usually the actuator head that fails and you can swap these without getting into plumbing, merely a few screws and a few wires to swap over.
     
  10. billfromarran

    billfromarran Active Member

    I will try to get a photo, Joe, but in the meantime this is what it looks like..
    The "T" is on its side, with the stem coming from the boiler. One arm goes down into a tank,and the other appears to go along the top of the cabinet and out the back. This one feels hot,which is strange as I am guessing that it is the supply to the rads. I can feel the pipe getting hot going up the wall towards the rooms, but the boiler cuts off after about 2 minutes. So the diverter valve would appear to be working,so why does the boiler switch off just as it gets going? There are 2 thermostat controls on th front face of the cabinet, one for hot water and one for C/H. Could it be that this thermostat is switching off too soon?I am only guessing here,so any advice is very welcome as it is getting a bit parky!
     
  11. Joe the Plumber

    Joe the Plumber Well-Known Member

    Could be a boiler stat. I'm afraid that's not my field though.

    Incidentally, it might be worth having a look at your house insurance (or British Gas cover?). You nay be covered for this.
     
  12. billfromarran

    billfromarran Active Member

    Thanks Joe, your input much appreciated. We don't have cover for this, but hopefully not a big Prob. Will try to get old of the heating bloke tomorrow. He services the boiler so should be able to solve the prob.
     
    Joe the Plumber likes this.
  13. billfromarran

    billfromarran Active Member

    Another day and I have been working my way through this..The hot water is working fine,but the C/H will work for about 2 minutes, supply to the first rad gets hot almost as far as the ad before it cuts out. I have to leave it for a while till it cools before I ca get it to fire up again. Heating temperatur control on the boiler does not "click" until it has cooled down a bit. I am suspecting that the heating control stat is faulty..but I am no expert.
    Still can't get hld of any heating bloke. They all seem to be unavailable.
     
  14. MGW

    MGW Well-Known Member

    As said the three port valve default is DHW, and DHW switches on the boiler from tank thermostat, so with faulty three port valve DHW will work, if the valve motors full over then all water must go through radiators or by-pass valve if fitted, if the water can't flow then boiler will cut out as you describe, be it pipes blocked, or TRV heads closed or lock shield closed if water can't flow boiler will close down, also if water is by-passed boiler will also close down, although it would take longer as would heat pipes.

    With TRV on all radiators there should be a by-pass valve so if all are closed the pump is not damaged, not always the case, in this house pump on return and no by-pass fitted, but only you can work out if water either circulating through by-pass or not circulating, could be also pump failed, often you will get some thermo syphon through pump to heat DHW, but very little will flow through radiators.
     
  15. billfromarran

    billfromarran Active Member

    The actuating motor was working fine, changing the flow from HW-Both-Heating. however ,in the heating mode, the pump was not being triggered. We eventually traced this to a faulty microswitch . Heating is working 100% now. Thanks for all the replies.
     
    MGW likes this.

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