Valiant boiler and controller not working as expected

[stinkybagpipes]

I recently moved into a house that has a Valiant ecotec plus 415 boiler, gravity fed with an hot water tank. To get the boiler to heat the hot water I have to manually set the heating flow temperature (which is the central heating setting) on the boiler itself. The controller we have downstairs by the thermostat does seem to do anything. The DHW temp is set at 50deg

If i turn the heating flow temperature to 0 then it turns off the central heating and doesn't heat the water. The heating controller has options for heating and hot water but none of the functions seem to do anything on the boiler. It was recently serviced (before I moved in) and it came up with a clean bill of health. Any suggestions on what to do next?

 

[Johntheo5]

The DHW temperature is normally set on a thermostat, called a cylinder stat, strapped on to the HW cylinder, a 50C HW temp means the Boiler Flow temp, the CH temp, should be left set to 60C or higher, if HW only requested, then the boiler should fire up and when the HW temp reaches 50C then the boiler should shut down.

 

[Mottie]

AFAIK, unless you have the dedicated Vaillant controller that fits on the boiler, the only setting available for hot water and heating is the flow temperature. I set mine at 62°.

*With the Vaillant controller you can set different flow temperatures for heating and hot water.

 

[fixitflav]

The controller we have downstairs by the thermostat does seem to do anything.

Which thermostat is that?

Is there a roomstat, or does the boiler just fire when called by the controller?

Is there a 3-port valve or two 2-ports, or what?

It was recently serviced (before I moved in) and it came up with a clean bill of health. Any suggestions on what to do next?

Sounds like he checked the boiler was OK but took no interest in the overall system.

 

[stinkybagpipes]

@fixitflav There is a room thermostat, when I turn it up the central heating comes on and the rads get warm. When I turn it down the boiler still heats the hot water even though the controller has heating and hot water set to off.

The controller is Sunvic SELECT 207 XLS.

 

[fixitflav]

@fixitflav There is a room thermostat, when I turn it up the central heating comes on and the rads get warm. When I turn it down the boiler still heats the hot water even though the controller has heating and hot water set to off.

The controller is Sunvic SELECT 207 XLS.

Any valves?