hot water question



i'm hoping someone can offer me some advice with my central heating system. i've attached a picture of our airing cupboard. we have an old ideal boiler (not combi) downstairs with a thermostat in the hall

during the summer, we had the programmable timer set so that the heating was off and the hot water came on twice a day. this worked fine until we turned the hot water off for a week while we went on holiday. when we got back, we set the timer so the hot water came on twice a day as before, but the water refused to get hot. as a test, i set the hot water to constant and it still didn't get hot. the only way i could get hot water to work was by putting the heating on as well. it was almost like the water couldn't get hot on it's own and would only work if the heating and water were BOTH on at the same time. so we've been running with the heating is on constant (controlled by the thermostat downstairs) and the hot water comes on twice a day. this has been working ok, but yesterday the hot water stopped working again! even though the heating is still set to constant on the timer. i managed to fix this by turning off both hot water and heating on the timer, and switching the power off and back on to the small white box on top of the copper pipes in my picture. i then set the timer to heating constant and hot water twice a day again. it seems to be working ok at the moment, but does anyone have any thoughts/suggestions as to what's going on with the hot water?


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Do you have a multimeter and can you safely use it with mains voltages? I'm afraid you would have to venture into the wiring centre/junction box on the wall under the programmer to find out what's happening.

The programmer may not be reliably supplying the Hot Water ON (230V) signal, or the cylinder thermostat may not be switching the signal through to the boiler.
i'd rather not start playing around with the electrics if possible, but i've recorded this video to help explain the situation. i think it could be something to do with the actuator valve perhaps???....
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Yes, but to diagnose the fault you, or an engineer , will need to test with a meter on the wiring centre!

one other thing i forgot to mention, and i'm not sure if it's related, but our central heating has started to make some funny noises recently. for example, in our downstairs toilet you can hear water splashing about in the pipes or the radiator! it sounds like someone's chucking a small bucket of water about! also, sometimes there's a moaning/groaning sound as the heating or hot water kicks in. i've bled the towel rail in our main bathroom upstairs, and there was loads of air in it, so i'm going to go around the house this evening bleeding the rads in every room. could this potentially be the cause of the lack of hot water??

No there's an electrical problem stopping the boiler firing up when hot water is required. It's most likely going to be the cylinder thermostat or the programmer and associated wiring.
when the heating is on the boiler is firing up fine - the rads get hot but the water still runs cold. is this not likely to be the mechanical valve that's broken more than the wiring? i know nothing about this stuff, i'm just going on what i've read from old posts and other online articles

But when you set the programmer to hot water only, I gather the boiler isn't firing up.

That isn't the fault of the 3 port valve.

With hot water only the valve stays at it's rest position and the boiler/pump get the signal to run from the programmer and cylinder thermostat.
just to let you know, i managed to get the hot water working again last night. i basically turned off heating on the programmer/timer, and left hot water on constant. i then turned the thermostat on the tank right up to 80 degrees to see if it would make the boiler kick in. it didn't. so i put the heating and hot water back on. i had a little fiddle with the lever on the 3 way valve and it seemed to be ok. i also went in to the loft and moved the ballcock in the f&e tank and it did seem to feel a little stuck (even though there was some water in the f&e tank)

anyway, after all that, the hot water started working again? the next test is to put it on the timer, rather than constant, to see if it continues to remain hot


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