Central heating Electrical Problem

Discussion in 'Plumbing and Central Heating' started by NigelC, 15 Oct 2016.

  1. NigelC

    NigelC

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    System - Gravity fed basic CH system, Rad Stats (no room Stat) , 2 motorised valves (one for Hot water and other for CH) Grundfos UPS2 Pump (fairly new 2-3 years old).
    Went to turn Hot Water on and the controller (Honeywell ST699) was dead, evetually found a 3 amp fuse in the boiler electrical switch which had blown, replaced this and controller came on again, I reset the time and then turned the Hot Water on and the fuse blew again, rather than going round checking all the wiring thought I'd try a 5 amp fuse which worked, boiler kicked in but stopped after about 5 mins (there was electrical power still) noticed that rad in the bathroom that is on the Hot Water system was still cold, Boiler wouldn't start even with turning boiler temp control up to 90 degrees. I'm now guessing the water is not circulating out of the boiler, checked both motorised valves and they seem to be working however looks like no power to the pump (pump has 3 lights on it to show what speed its set to).
    Could this be the Controller ? it is about 19 years old and the Led display is not showing all the digits nowadays. As mentioned I only fitted the new Grundfos UPS2 pump about 2-3 years ago, is there a seperate fuse for the pump. Don't want to splash out nearly £90 for a new controller/programmer if thats not the problem.
    Any help would be appreciated
     
  2. oilboffin

    oilboffin

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    First mistake never put a larger fuse in than you take out you can cause more damage and if you don't know don't touch,get an electrician for safety.
     
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  4. picasso

    picasso

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    Grundfos had a problem with some of their ups2 pumps , the inrush current was frying the contacts on the programmers, might be your problem.
     
  5. chivers67

    chivers67

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    If the pump is failing, it's likely to be drawing more electric current which is why the fuse could be blowing and as Oilboffin mentions by placing a larger fuse the wiring is no longer being properly protected.
     
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