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Mar 23, 2023
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London
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DIY or Homeowner
If the hot water is on, hot water is running round the CH system, even if CH is switched off.

Vaillant tell me that you control the temp of the HW at the tank. And indeed I can’t adjust the water temp at the boiler.

But if I increase the temp of the CH, the HE gets hotter.

Also, if I turn the CH off at the boiler, there is no HW, even if switched on.

Any ideas?
 
Sounds like motorised valve failure. I’m guessing you have a heat only/system boiler? The central heating water is used to heat the hot water cylinder independently from the heating as it has its own circuit, controlled by motorised valves.
 
Sounds like motorised valve failure. I’m guessing you have a heat only/system boiler? The central heating water is used to heat the hot water cylinder independently from the heating as it has its own circuit, controlled by motorised valves.
Thanks where would the motorised valve be? We’ve changed something, I think it was called a 3 way valve, twice. No dice from that.
 
3 port valve might be what you’ve changed, don’t think there’d be one in that boiler. It would be near the hot water cylinder. Did you cnahge the full valve or just he motor head?
 
3 port valve might be what you’ve changed, don’t think there’d be one in that boiler. It would be near the hot water cylinder. Did you cnahge the full valve or just he motor head?
3 port valve might be what you’ve changed, don’t think there’d be one in that boiler. It would be near the hot water cylinder. Did you cnahge the full valve or just he motor head?
Yes , it’s by the cylinder. And I’m pretty sure ve changed the valve (twice) and it didn’t fix it. If that’s the one you’re talking about, do you have any other ideas?
 

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