Hot water not hot!

Discussion in 'Plumbing and Central Heating' started by kingkevbo, 7 Nov 2003.

This topic originated from the How to page called Problems associated with noises from the central heating system.

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  1. kingkevbo

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    I have a problem where the hot water does not get hot when you run a bath or open the hot tap on the kitchen sink. I have a combi boiler. The hot water is fine for a shower but it seems like the boiler cant cope with the demand of a large amount of water.

    Please help!

    Thanks
     
  2. oilman

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    Let's have some info then. Clever we are, clairvoiant were not.

    What boiler type, does it fire when you turn the tap on? does it get hot if the flow rate is low? What else do you know which you should tell us?
     
  3. kingkevbo

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    sorry oilman, i should have been more specific.

    The boiler is a combi; chaffoteaux at maury stirling PP, I dont know how old it is, I have just moved in to the house.

    The boiler does fire when the tap is turned on and the water does get hot if the flow rate is low i.e. the shower or a low flow from the tap.

    However, if you try to run a bath or put the kitchen sink hot tap on full blast, then the hot water temperature is only luke warm.

    The central heating works fine, the radiators get very hot, no problem there.

    Also whilst showing the hot water is very hot, but it sometimes fluctuates in temperature, I am not sure whether that is the boiler or the tap, as the shower is run off a rather cheap looking telephone type bath tap.

    Ok oilman, i think thats all. if you need anymore info, just say so

    Cheers, Kev.
     
  4. ChrisR

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    Guessing a tad, your combi should give you about 9 litres a minute of hot water with its temp raised through 35ÂșC. That will come out at about showering temp (38-40). So get a 10l bicket and measure the flow rate you're getting at the shower.

    Any decent tap full blast will give you tepid water! That's combis for you. The energy input is shared , as it were, by all the water.
    If the flow rate is lower than it should be, or the combi switches itself on and off a lot while you're drawing water , leading to the fluctuations, the problem is probably sludge/scale build up inside the combi. Cleanable.
     
  5. kingkevbo

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    I understand that the quicker the flow rate the less time the water will spend inside the boiler and the lower the temp will be, i mean any combi boiler should be capable of running a bath! even if it takes a long time but this boiler can not run a bath at any reasonable temp.

    I have lived in houses with combis before and never had problems like this, i am sure that there is something wrong with it

    the boiler does not switch off while it is running but i will have a look to see if there is any sludge. I think it is unlikely that anything has calcified because i live in stockport which has very soft water.

    If anyone has any ideas please help.
     
  6. Giblets46

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