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Loud banging from airing cupboard when Hot Water is on.

Discussion in 'Plumbing and Central Heating' started by BoutTime, 10 May 2017.

  1. BoutTime

    BoutTime

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    Good morning all.

    We've just moved house and noticed that the HW Cylinder Thermostat was only set to 50 deg C and the hot water didn't last for long. I've raised the temp to 60 but now we are getting really loud noises coming from the airing cupboard when the heating has been on for about 1 1/2 hours. Lots of banging and it pretty much sounds like an old spitfire engine idling. I figured the water may be getting too hot (it is very hot now at the taps) and boiling off or just venting to the F&E Tank. For info the pump is set to the mid position and I've bled it already with no traces of air.
    I looked at the F&E tank and the water inside is warm. Interestingly there is no vent pipe but there is a vent pipe to the Cold Water Feed Tank. I understand some systems have a combined feed and vet pipe, is this correct?
    A replacement Thermostat is only about £17 so should I just give it a whirl or do you think the issue may lay elsewhere? I'll post a link to a video of the noise so hopefully it will work.

    Many thanks in advance!

    https://goo.gl/photos/tNpiCpbfSvk1baMT7
     
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  3. DP

    DP

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    Which thermostat did you alter?
    One that is strapped to side of the cylinder or the one that is inside the immersion heater.

    If the strapped one, then doubt that will be the issue.
    Where is the loud banging coming from? Check the boiler. Turn the thermostat on the boiler to a lower setting and see if that makes a difference after you have checked what is suggested below

    Run boiler in HW mode only and check noise. While boiler running, check header cistern. If there is surge of water randomly, turn down boiler thermostat to a lower setting and check again
     
  4. BoutTime

    BoutTime

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    Thanks for getting back to me DP.

    These noises have only occured when the Hot Water is on at the programmer and once the water is hot. I put the immersion heater on shortly after and these noises did nor re-occur so it seems it only happens when the hot water is heated by the boiler. They do not occur with just the heating on although to be honest we've not run the heating for too long in this weather. Th noise 'seems' to be coming from the pipe which the pump is on but I'll have to check again if/when it re-occurs. It wakes us up and I only have a short time to get to the airing cupboard and check.

    When we moved in the boiler was set to 4 (scale 1-6). The Cylinder (strap-on) Thermnostat was set to 50 deg C. I turned the Cylinder thermostat up to 65 and then down to 60 deg C, and the boiler up to 5 (scale 1-6). Should I turn the boiler back down to 4? The hot water is now bloody hot!

    Just for further info, we had the aweater programmed to come on for 2 hours in the morning and 2 1/2 hours late afternoon. Is this too long as we are used to a combi-boiler?

    Thanks again.
     
  5. DP

    DP

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    Restore the boiler thermostat to lower setting
    Noise might be there during HW because water will have heated very quickly with boiler now cycling and burner staying on well past the shut off stage due to thermostat being 'out of tolerance' and not shutting the burner off at set temperature or slight lag in doing that.

    Get the system checked by someone who will do a proper system check including proper service.
    Post you location here, might get some real engineer respond to assist you.

    Improve the controls on present system, avoid the combi route
    Periodically switch the immersion heater on to keep it in good order
     
  6. BoutTime

    BoutTime

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    Cheers. Just ran a downstairs tap and the hot water is far too hot so I've turned the boiler setting back to 4. We are having a Nest Thermostat installed tomorrow but by an electrician rather than a heating engineer. But he is approved by Nest. The boiler itself was serviced prior to us moving in.

    The flat drive for adjusting the HW Tank thermostat is in a right mess so someone has obviously been fiddling with it before.

    We are in Trowbridge, Wiltshire.
     
  7. Hi,
    55 degree c on the cylinder stat.
    Boiler thermostat at 3.

    If the adjusting screwdriver slot is all munched up then thats a clue,best change it for same manufacture type as will have same wiring.make sure there is positive contact between the cylinder stat and bare cylinder.

    The previous owners may have run the boiler at a lower setting ie 2 in the summer months.
     
  8. BoutTime

    BoutTime

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    Thanks, just out of interest.....I'd read the minimum temp for storing the hot water is 60 deg C in order to kill bacteria. Which is one of the reasons I turned it up. Is this true?
     
  9. BoutTime

    BoutTime

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    So what are the optimum settings for cylinder and boiler temps, and programmer?

    How long should I have the HW on for at the programmer roughly?
     
    Last edited: 10 May 2017
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  11. depends on the hot water demand,many just leave hw on 24 hours,
     
    Last edited by a moderator: 4 Jun 2017
  12. BoutTime

    BoutTime

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    Just a bit of feedback....the tank thermostat appears to be working, just not sure it's that accurate. I just turned the HW on to heat and the boiler fired up. I also switched on the immersion heater to speed things up. Shortly after the boiler turned off. I then turned off the immersion heater and increased the cylinder thermostat until it clicked. The upper two port valve moved over and the boiler came back on. I then turned the stat back down until it clicked and the valve moved back over and the boiler turned off.

    But the pipework is bloody hot to touch. The only thermometer I have is for our barbecue. If I can find it I'll put it on the cylinder and pipework and take a reading.

    Thanks again for your help.
     
  13. Alec_t

    Alec_t

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    There's a thought.... barbecueing on the pipework.:D
     
  14. BoutTime

    BoutTime

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    So I ran the hot tap through after the HW turned off via the thermostat. 56 Deg C donut seems to be calibrated. Will see how it is in the morning as I've turned the boiler down.
     
  15. Mark Oliver

    Mark Oliver

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    I know this is an older post but did you solve this problem? Ours is making the exact noise but having no luck in solving. Pump has been changed and now has the boiler thermostat.
     
  16. BoutTime

    BoutTime

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    Try turning the hot water cylinder thermostat to a maximum of 55-60 deg c. Then turn down your boiler thermostat. Another thing I did was slightly open the tap on the bypass valve adjacent to the hot water cylinder if its a manual valve like on our system. This will send hot water through a bypass and back to the boiler like an idle circuit when the control valves close. I'm no expert and just going from memory.

    It seemed to be caused by the system kettling. The water in the system got too hot and with the heating off it had nowhere to go hence the banging.
     
    Last edited: 3 Oct 2019
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