Hot Water Coming On With Heating

[Fayecb]

Hi,
We've just moved in to a property that has an Ideal Mexico 2 Boiler downstairs, a water tank in a cupbaord upstairs and in the loft 2 water tanks, a large one and a smaller one. When we moved in they had both the heating and water on constantly and the thermostat turned down for the radiators when not required. We had an electrician upgrade the old thermostat with a Nest but now when we put the heating on the radiators get boiling hot and can't be controlled. If we just have the heating on then we can control the temp ok. We called the electrian back who then said it was the boilers fault and an issue with a valve. We've had someone to look at the boiler and no valve can be found. Well and truly stuck and don't know where to turn. Any help would be much appreciated. Thank you

 

[king of pipes]

As Shaun says it needs a re pipe and controls upgrade to a s plan you cannot separate the heating and hot water the way it is now . Kop

 

[Timmy D]

As Shaun says it needs a re pipe and controls upgrade to a s plan you cannot separate the heating and hot water the way it is now . Kop

I agree that it should be s-planned.

Have a look at the link I posted. If you connect the cylinder stat inline after the “2” tee on the “L” to “6” wire, you get control of the system. Heating or hot water wouldn’t back feed.