Please Help - Got Hot Water but no Heating on Combi Boiler

Discussion in 'Plumbers' Talk' started by Maza03, Dec 4, 2019 at 9:12 PM.

  1. Maza03

    Maza03 New Member

    I have a Worcester Bosch Highflow 400 Boiler. On Saturday night my partner topped up the boiler from 0.5 to 1 & since we have had no heating but still have hot water. When I turn the thermostat on it calls for heat - well the demand light comes on for 30 seconds. Topped it up to 1.5 but still nothing. Bleed the radiators 2 filled with air but as we bled the radiators the pipes feeding the radiator were heating up.


    (The pump is still running perfectly fine)
     
  2. Mike83

    Mike83 Well-Known Member

    It could be the diverter valve at fault.
     
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  3. Maza03

    Maza03 New Member

    I was thinking that but wasn't sure as the hot water is still feeding the pipes when we bleed the radiator would that not mean the diverter valve is still working?
     
  4. Mike83

    Mike83 Well-Known Member

    No.
    A diverter valve will only close off either the flow or return but not both.
    So when you bleed a radiator, the radiator will fill from whatever pipe the diverter isn’t on.
     
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  5. The Teach

    The Teach Well-Known Member

    does the central heating demand light go out after 30 seconds ?
     
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  6. Maza03

    Maza03 New Member

    Yes
     
  7. The Teach

    The Teach Well-Known Member

    Oh right,the demand light (heating) needs to be fully illuminated for the period of heating demand it provides a signal for the diverter valve to open and deliver central heating. As mentioned by Mike83 the diverter valve needs to operate along with the switches supplying power for the diverter valve to remain open.
    There an easy boiler to do onsite fault finding,just need a multimeter. Really needs onsite investigation ;)

    Others may have other ideas ;)
     
  8. Maza03

    Maza03 New Member

    We have a multi meter here
    Thank You!

    We have a multimeter here so will have a look. I thought it was the thermostat not connecting to the boiler but ruled that out.
     
  9. The Teach

    The Teach Well-Known Member

    If you don't have the manufactures installation & servicing instructions for your particular appliance. They can be downloaded.
    There will be a section in the fault finding mentioning where to take mains :eek: voltage readings for your particular fail point.

    Maybe consider getting a gas boiler technician to do the repair,there an unusual boiler but easily repaired ;)
     
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  10. Maza03

    Maza03 New Member

    Oh Hell No I ain’t touching that! I worked with gas engineers I know what can go wrong & how dangerous it can be. I wanted to make sure it wasn’t something I could fix - broken thermostat, bleeding air from the radiators or topping up etc but the boiler internals ain’t something I would even think about. Not to mention how much more damage can be done when you’re not a trained engineer it’s just not worth the hassle!

    Thank You! You’ve all been a great help!
     

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