Heating acting up

Discussion in 'Plumbers' Talk' started by toil and trouble, Nov 13, 2017.

  1. toil and trouble

    toil and trouble New Member

    The system is a Honeywell Y plan comprising of Switchmaster 600 (multi function programmer), a Thorn Olympic 38/50 boiler, Honeywell diverting valve, Honeywell room stat.
    The heating and hot water are both set to constant but the programmer seems to have a mind of its own, it comes on and off when it feels like it.
    At one point for a few days running it seemed to follow some kind of pattern, it would behave perfectly all night on low temp setting and work fine all day until the evenings around 6pm and then nothing, dead as a door nail, until sometime after midnight when we've all turned in it would come back to life, almost as if the programmer was on timed.
    As I said that was at one point but as things stand at the moment we could loose the heating and hot water at any time for one or two hours and then it would suddenly decide to start working.
    My guess is the Switchmaster has blown a circuit but any other ideas from you guys would be appreciated.
  2. Does the 600 have any indicator lights on it? Ie to show when it's putting the CH and/or DHW 'on'?

    If so, does this go on and off as well?
  3. The first basic test would involve turning the 600 off and then observing the 3-port diverter valve as you turn on the 600, one channel at a time, and then also turn the relevant 'stat up and down beyond its 'click' points. (Ie the cylinder stat and the room stat, in turn).

    It could be any of these components at fault with dodgy connections. Process of elimination.

    Eg, if you cylinder is full of hot water, the stat on there should go 'click' at around 60 to 70oC. Does it? And if the 600 has the DHW 'on' at the same time, this should start up the pump and boiler. Does it?

    Ditto for the CH side - turn on the 600's CH, and then try the room stat up and down. Where does it click - is it close to expected room temp? And when you turn it up, does the motorised valve whirrrrr and 'click', thereby turning the pump and boiler?

    If these tests don't reveal anything, you really need a volt meter...
  4. The Teach

    The Teach Well-Known Member

    some parts of the installation could be defective but (as long as the system is installed correctly and the end user not expecting more than what the existing controls can do)

    However tests (visual and with instruments) can be carried out on how well the system is working,or the diy approach would to exch the 3 port valve and the room thermostat.

    Everyone has different heat requirements ;)
  5. toil and trouble

    toil and trouble New Member

    Hi Guys It is now Monday 13/11/17 the time is 16-30 and its the end of a really gruelling day for me. Believe me retirement is just another word for hard graft.
    Thank you for your replies and I will carry out further tests and try to get to the bottom of this strange problem.
    What I can say is the system was installed back in the 70s and it hasn't missed a beat until now.
    Logically if a component fails it should stay failed, but in this case what ever is causing the problem is an intermittent fault.
    Having said that today is a different ball game altogether, the heating died around mid afternoon and has not come back on as yet.
    At the moment I am up to my neck installing a complete new bathroom, plumbing, stud walling, tiling, etc but when I get five minutes I will conduct further tests on my CH hopefully with the help of an electrician.
    Thanks again for your replies, I will keep you posted as to the outcome.

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