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Boiler keeps turning on and off, house not getting to temp

Discussion in 'Plumbing and Central Heating' started by danoid, 25 Nov 2014.

  1. danoid

    danoid

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    So our boiler keeps turning on and off.

    I set the house stat to 20oc, then turn the boiler on at the controls, few seconds later it clicks and it's firing away.

    Few minutes later and I can feel heat in the radiators, lovely jubly but then the boiler will turn off! Then maybe 5 mins later and it's back on, eventually after almost 3 hours the radiators are quite hot, I can hold the front of my hand on them for a while but not the back of my hand.

    Our house is 1994 (same boiler) semi, well insulated but never gets to the temp that I set the stat at.

    Something is wrong but don't know what and was hoping for suggestions as to what it could be and how much for part and fitting roughly

    Thanks[/b]
     
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  3. 45yearsagasman

    45yearsagasman

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    Crystal balls at the ready chaps. Mine is broken. You've probably got a circulation fault, buts that's all I'm prepared to guess at. All we know is that you have a boiler.
     
  4. Plumber90

    Plumber90

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    If the rads don't feel like they're getting that hot check what the temperature dial on the boiler is.
     
  5. scoobydo123

    scoobydo123

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    Also possibly very relevant is the room stat.
     
  6. ALCPlumbing

    ALCPlumbing

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    The hint when crystal balls where mentioned is that it might, just might, help if you told us what boiler you have. We're good but not that good. I've booked up to get my mind reading ticket next week.
     
  7. Agile

    Agile

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    We just need the Scruff because he has X-ray vision and can see boiler models from 300 miles away!
     
  8. danoid

    danoid

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    It's called Ideal classic, then says Stelrad Ideal Rs30.

    The setting on the boiler is 5 out of 6.

    The radiators do all get very hot eventually, need to balance them as upstairs is very hot whilst downstairs is just getting warm, but the on then off isn't helping downstairs heat up
     
  9. Scarum

    Scarum

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    Is this the answer to your problem?
     
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  11. danoid

    danoid

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    Well that's just the thing.

    Would an unbalanced system keep turning the boiler on & off?

    It's usually on for 15minutes, then off for 5, then back on etc, but when I look at a thermometer the house is only at like 14oC from 12oC.

    In my mind, if the room stat is turned to 20oC, and the house is 14oC, the boiler should heat up the radiators until it gets to 20-21oC, then turn off.

    But instead it's on off, for hours slowly creeping up a 0.5 of a degree each time it seems, and time the house gets to 17oC, I'm usually fed up as it's been doing not alot for hours
     
  12. danoid

    danoid

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    Also some more information may or may not be helpful, but in the airing cupboard is the pump and 3 way valve. Which is ACL, diverter valve is it?

    If I turn the hotwater on a little spindle turns to W, then if I turn that off and put the heating on, it turns to H. So guessing that bit is working?

    The pump sounds good, extremely hot to touch on the outside though. Bit like what I think our radiators should feel like! But it all sounds good from what I can hear
     
  13. Gasguru

    Gasguru

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    Just a few options to start with in no particular order....

    The radiators need to be balanced otherwise the water returning to the boiler will get hotter quicker and the boiler thermostat will operate sooner than it should and the property will take longer to heat as the boiler shuts down more often.

    You should also check let-by on the 3 way valve. Allow the system to cool (and preferably the cylinder cold too). Run just the heating and check the temperature of the pipe from the diverter (mid-position) valve to the cylinder. If it's getting appreciably hot the valve may be letting by meaning water will be returning to the boiler again operating the boiler thermostat.

    Poor circulation due to wrong pump speed/weak pump/ blocked pump/blocked pipework/lack of water in the system etc.

    Bypass open too much (if fitted)

    Boiler thermostat out of calibration...on maximum the water will be around 80 degrees c.

    Feel the temperature across the flow and return pipes off the top of the boiler...if there's a significant difference it indicates poor flowrate.
     
  14. danoid

    danoid

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    Thanks for that.

    I have a question regarding balancing the radiators.

    When checking which ones heat up first. Is that fully heated up, or as soon as I feel heat on the pipe?

    Thanks
     
  15. Agile

    Agile

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    So your boiler is only on for 75% of the time, that's not helping!

    Whats in your mind is not the case! The boiler turns off as soon as the flow reaches the set value and goes into anti cycle delay.

    If only you read their FAQ on this site before posting then you would read all about it and how to balance the rads!

    Tony
     
  16. danoid

    danoid

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    Radiators not balanced correctly and the house is warmer, so I thought job done.

    However I thought I'd put the house stat to max 30oC and guess what!? The boiler is still turning on and off after x amount of times. I've turned the pump from setting 2 to 3 and not made a difference.

    All radiators hot, have no trvs and boiler still kicking on and off automatically.

    What does this sound like now?

    The flow pipe is much hotter on boiler than the return.

    Or are you saying the boiler on off is fine and meant to turn on and off? And not what I thought, which is it constantly on until it gets to my desired temp
     
  17. JohnD

    JohnD

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    "not?" or "now?"
     
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