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Boiler fires up for H/W but not C/H

Discussion in 'Plumbing and Central Heating' started by RosieC, 29 May 2020.

  1. RosieC

    RosieC

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    Hello all,

    I’m pretty clueless when it comes to this sort of thing but as we can’t have tradesmen in the house due to shielding I’m hoping someone can give me advice to help diagnose my heating problems. We bought this house less than a year ago and starting to find that there are several little ‘problems’.

    We have a Potterton boiler, with a header tank in the loft and an immersion heater in the airing cupboard. It’s controlled with a British Gas UP2 wall controller and we have two thermostats - a satchwell in the living room and acl Drayton at the bottom of the stairs. The valve in the airing cupboard is also an ACL Drayton.

    Our heating and hot water was working fine but has recently started playing up.
    When I press the wall controller for hot water the boiler starts running and producing steam and it heats the water up.
    When I press the wall controller for central heating nothing happens. The thermostats are set at maximum temperature. And the heating still didn’t come on even when it was very cold.

    We were told to replace the motor in the motorised valve so did so. It didn’t make any difference.
    When I push the lever into manual we get heating.
    Someone said that the actuator might be broken so we’ve purchased one of those but the valve needs replacing too because it’s so old. So before I mess around with that I’d like to check to see whether I’m doing the right thing.

    Please can someone point me in the right direction?
     
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  3. ianmcd

    ianmcd

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    Post some photos of your motorised valve and your programmer when heating is called for
     
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  4. WestmidsDIY

    WestmidsDIY

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    Most likely The motorised valve sticking as mentioned above.
     
  5. RosieC

    RosieC

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    Thank you. Would this prevent the boiler kicking in when I use the wall controls to call for heating?
     
  6. WestmidsDIY

    WestmidsDIY

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    Yes, if you can manually move the lever on the valve and the heating kicks in, get the valve replaced when safe and possible. It’s a fairly common fault on y plan (one 3 way valve) or s plan ( 2 x 2 way valves) heating systems.
     
  7. RosieC

    RosieC

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    Thank you so much!

    Do you think this is a job an amateur might be able to do?
    I have a valve and actuator and as far as I know I have to drain the system with electric off, replace valve, wire it in and then fill system ?
     
  8. WestmidsDIY

    WestmidsDIY

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    If you’re confident to carry out the work. It may be worth considering re filling the system with Chemical inhibitor, and also look at possibly picking up a mag filter if you haven’t one already fitted to drop on the primary return, to help keep the system clean. Sometimes the cause of sticking in the motorised valves can be build up of dirt in the heating system.

    good luck
     
  9. RosieC

    RosieC

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    Fantastic ! Thank you!
     
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  11. ianmcd

    ianmcd

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    As already asked please post a pic of the valve, unlikely that you will have to drain anything unless it is really old
     
  12. RosieC

    RosieC

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    Hi, thanks for your reply.
    It’s super old - an old Drayton acl.
    Hasn’t got the removable actuator
     
  13. Funkyfreddy

    Funkyfreddy

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    As mentioned post an actual picture of the valve that controls your CH - would help.

    If moving the lever manually triggers the microswitch and turns the boiler on them it would seem your electrical circuit seems to be OK.

    Maybe the synchro motor has failed, if you can remove the cover and you can perhaps check the synchro is working when powered up or manually move the valve as it may just need a bit of persuasion if it has become a little stuck.
     
  14. FiremanT

    FiremanT

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    If there are two room stats, there should be another valve (total of 2 ports for heating and 1 for HW). But if those 'stats are on the same floor, am I right in suspecting that this is an old (60/70's) house that has a heating system upgrade at some point? In which case, one (probably the Satchwell) is actually non functional.
     
  15. RosieC

    RosieC

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    Hi FiremanT, yeah it’s a 70s house.
    Although at one point she actually had solar panels put in!
    I didn’t realise one would be non functional, but I think if that’s the case it’s definitely the satchewell as I can hear the Drayton clicking sometimes.
    Do you mean there should be another motorised valve somewhere, other than the one in the airing cupboard?
    Sorry, I’m very new to this...
     
  16. FiremanT

    FiremanT

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    Hi. No. The original description was slightly confusing. Very modern homes have "zones" each with a thermostat. So you can set the heating to work during the day in the living areas, but be off in the bedrooms etc. Each 'stats has to operate a valve. So your original description would have needed valves with a total of three ports, or outlets. But, on re reading I realised that the one stat was in the hall, and one in the lounge. This led me to the conclusion that I outlined - but it is not impossible to have a lounge on the first floor.

    Anyway, the clicking does not indicate that the stat is live or otherwise. Does the Satchwell have a knob, or is it a slider with a red line as the indicator? If so, this is ancient, and is probably left over from the old system. But beware, it is possible, but unlikely, for it to be still connected to power. It is more likely to be disconnected bot left in position to avoid damaging decor. Or laziness.

    How DIY are you? can you confidently use a multimeter? And please post the requested pics - it makes life a great deal easier. Of the valve(s), room stat and airing cupboard arrangement.
     
  17. RosieC

    RosieC

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    Thanks for the reply.
    Will get pictures shortly and upload them ☺️
     
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