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Thread: Central Heating but no hot water

  1. #1
    Automated Home Jr Member
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    Default Central Heating but no hot water

    Please help!!!!

    I have recently had a few more radiators installed in my home. Came to switch them all back on and they work fine, hot through out the radiator but I now cannot seem to get any hot water.

    I do not know the specifics of the system. I will find if required. Could it be the programmer which is located in the airing cupboard (sp), or a air lock in the system or the three way valve which I keep reading so much about on here. I am a complete novice so forgive me if the terminology is not correct.

    The programmer can be used to control the central heating and hot water separatley.

    The immersion heater now no longer works as well. I have checked all electrical feeds, so there is electricicty getting through but im not sure if it making it into the programmer/control switches. Any help will be much appreciated!!

    Paul

  2. #2
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    Default Re: Central Heating but no hot water

    Come on please guys, from the sounds of it your all experts on here - some one must know what the matter is ? If I can get this sorted by someone here, i'll send you some beers.... I work for a brewery!!

  3. #3
    Automated Home Legend TimH's Avatar
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    Default Re: Central Heating but no hot water

    Did you ask whoever installed the radiators for you to recommission the system afterwards? If so, did it work when he left? If it didn't work then I think your best recourse is to get the guy back to fix it himself :-)

    Do you have a 3-port valve, or two 2-port valves? A 3-way valve is sometimes located near your hot water cylinder (airing cupboard). If you look at the valve does it have 3 pipes coming up to it? If yes, then it will be a 3-way valve :-) Failure of the actuator is fairly common and the motor can usually be replaced without draining down. If the valve itself is sticking then you may have to pull it out & refurb / replace. How old is this system?

    Can you tell whether the valve is moving or not? Some have indicators on them (little bits of metal sticking out of the motor box on top) to show what position they are in. You can adjust the times on the time clock to force the water on - does the valve move, or make any noise at all? What if you turn the heating on & off, any difference to the valve?

    Have you tried bleeding air out of the system? There should be an auto air vent located at a high point, mine is near the hot water cylinder in the airing cupboard. Mine is screwed to the pipe and a quarter turn of the whole body is enough to tell whether air escapes or not. If it does, let it bleed out until you see water weeping fom the threads. Be careful though as you could end up with a large leak if you undo it too far, or pull it off :-(

    Re: the immersion heater. If you're measuring power at the heater itself then it sounds like the element or internal thermostat has failed. Fairly common and also cheap to replace, but you will have to drain your system down again. Immersion heaters are not usually fed by the time clock and may have a separate feed all the way from the house consumer unit (fuse box).

    HTH,

    Tim.

  4. #4
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    Default Re: Central Heating but no hot water

    Tim, thank you very much for your response.

    To be honest i ve had two people look at it now and neither can find any three way valves, does this mean i will have a two way valve or?? the system is perhaps pretty old, a gravity based one?

    I have located the 'tap' you are talking about but this is faulty and is being replaced today, a guy tried to bleed the air from the system via a t piece which goes into the hot water cylinder, but this is also faulty - so..... had the whole hot water cylinder replaced and necessary pipework (cylinder was a quarter full of sediment and scale - so heavy couldnt really lift it).

    The imersion unit on the wall was faulty, live signals coming out of it but not going into the immersion in the tank. So thats rectified.... so at least i can get hot water via the immersion now. Is there anything else i can check?

    Paul

  5. #5
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    Default Re: Central Heating but no hot water

    Ok, the guy has finished installing everything but still no joy - i.e using the thermostat to heat the water. The device looks very tired and knackered, the central heating switch works but doesnt fire up the hot water. How easy is it to replace a thermostat for the CH and HW? I just need to know if it is reasonably straightforward or do I need to get another guy in to do this for me?

  6. #6
    Automated Home Legend TimH's Avatar
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    Default Re: Central Heating but no hot water

    Paul,

    So I assume your immersion heater now works?
    Did you ever get hot water heated by the boiler, or was it always by the immersion?

    Replacing the thermostat on the hot water cylinder is easy enough, just make sure you isolate the power first, and then double-check it's isolated. If it's an old system like you say, the stat will be switching mains voltage electricity. I presume that you've tried testing the cylinder stat by itself?

    Replacing the wall thermostat for central heating is also fairly straightforward but you need to study the wiring diagrams carefully for the old & new units to make sure you connect it properly. As before, the same caution is required as this is also likely to be switching mains voltages.

    It will be quicker to get a guy in to replace these, but they are not difficult tasks if you're reasonably confident with a screwdriver and volt meter :-)

    You say it's an old system, is it oil-fired? does it have a pump?
    You can't find a 3-way valve, have you found any two-way ones? They should be reasonably accessible i.e. you *shouldn't* have to lift floorboards etc. to get to them, but they may be tucked away somewhere odd. Have a look at the wiring for your time clock. There is usually a wiring diagram on the back, you may be able to deduce whether you indeed have separate CH & DHW circuits / valves or not.

    This site is quite useful - lots of pictures and there's also some wiring diagrams on there too (follow the "Installation" link from the home page).
    http://www.sunvic.co.uk/motorised.html

    The only other think that I can think of at the moment is that you 've got a valve *somewhere* that is shut, either a failed motorised valve, dodgy time clock, or a manual isolation valve that is closed.

    HTH,

    Tim.

  7. #7
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    Default Re: Central Heating but no hot water

    Hi Tim, yes the immersion now works so thats good for the time being.

    The system is a back boiler located in the fire place in the front room, the pump is accessible via the cellar. I have had this checked and all seems to be working ok?? Could it be that the module in the airing cupboard that activates the CH and HW is only working on the CH for some reason. i.e not switching over properly, therefore a faulty module. I will get the name and make of it tonight, but it looks like it has had a tough life, the fascia is hanging off and there is no centre piece for the timing function??

    I really have had a good rummidge all over the place but cant seem to find any valves that your talking about, do you have a picture so I know what i'm looking for?

    We have only been in the property for a month or so, I am sure we have had the hot water working before via the terminal in the airing cupboard before we started to decorate and replace radiators.

    Thanks for your responses Tim, if you can get this to work for me i promise i will organise some Spitfire (kent ale) is sent your way!!

  8. #8
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    Default Re: Central Heating but no hot water

    Ah Tim, sorry I see the pictures of the valves erm... nope nothing like as far as i can see

    Paul

  9. #9
    Automated Home Legend TimH's Avatar
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    Default Re: Central Heating but no hot water

    Quote Originally Posted by Tank32
    if you can get this to work for me i promise i will organise some Spitfire (kent ale) is sent your way!!
    aww shucks... ops: thanks!

    This page may of interest / help too:
    http://www.miketheboilerman.com/pipeworklayouts.htm
    your system sounds a bit like the 1st diagram / description. Quoting from that page
    hot water alone can be selected but not central heating alone. Central heating can only be selected when hot water is also selected
    Also have a look at the Honeywell link on the same page, that has some info, and instructions for installers on how to upgrade semi-pumped systems.

    And another diagram. Similar to the above, but the text is a little different. It also seems to suggest that for semi-pumped systems there is no cylinder thermostat.
    http://www.gasman.fsbusiness.co.uk/g...ed_heating.htm

    The next step is probably to sketch out your system - aiming for a diagram that looks like those in these links. This will lead you to find & identify all the relevant components in your system.

    Just thinking aloud, when your DHW cylinder was replaced, did the plumber flush out all your pipework? I guess it's possible that the feed to the cylinder could still be furred-up / blocked. Does the pipe to the cylinder warm up at all?

    HTH,

    Tim.

  10. #10
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    Default Re: Central Heating but no hot water

    Tim,

    Hmmm, i'll check that out "the feed to the cylinder'. Should that get hot?

    Is there anything that can be put into the tank up stairs in the loft that will clean the system through? i.e de-fir the pipe system?

    I do have hot water now, through the immersion? Funny really though that the feed coming from the immersion controller was showing live, the feed to the actual immersion was showing live, yet re connected the immersion to a different socket and it worked fine, hot water?? So I am assuming the immersion controller was knackered? Maybe the same with the CH HW controller in the airing cupboard??

    Presumably the pipes arent firred up, as i can get water through the whole system, i.e to the taps and radiators seemingly without interference?

    I dont suppose you live near margate kent do you so you could over and have a look for me? And to collect your beer?

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