Hot water/heating type.

[barrowfordred]

I have a boiler which heats the central heating radiators and the domestic hot water in a cylinder. The heating can be controlled by a thermostat on the wall. But I can't figure out how the hot water is controlled?
There isn't a stat on the water cylinder.
There is a Honeywell valve after the pump outlet pipe (I think) has split. One to the water cylinder and the other ,with the valve on it I assume goes to the radiators.
I can only have the radiators on if the water is also on.
I can have the water on alone.
I assume the honeywell valve stops the pumped water from reaching the radiators if the heating is off, but what stops the boiler continually heating up the domestic hot water?
There is a dial on the boiler (can't find a makers mark) which can be set to off and has a varying scale on it to suggest as it is turned heat increases. Altering this turns the boiler on and off.

 

[sime10]

Doesn't sound right not having a cylinder stat

 

[Gas2Air]

Your system is C plan the valve you mention only energises under the roomstat and brings the pump on only, It's a glorified gravity system. Your only HW control is via the boiler stat. I suggest you update it.

 

[barrowfordred]

Definately can't see one. Only thing it has is an electric emersion heater.
It looks like this -
http://www.gasman.fsbusiness.co.uk/images/sppic.jpg
but without the top 2 port valve Just the bottom one.

 

[barrowfordred]

Your system is C plan the valve you mention only energises under the roomstat and brings the pump on only, It's a glorified gravity system. Your only HW control is via the boiler stat. I suggest you update it.

Thanks very much for that. Sounds expensive

 

[barrowfordred]

Could the system I describe above be simply updated by adding another valve to the DHWS to the cylinder and a thermostat to the water cylinder?
And then link this into the controls?
My heating & water control unit is a new programmable one.