Drayton Lifestyle Lp722 not turning heating off

[Pod1972]

I have a problem with our combined central heating and water heater system, it runs from a drayton LP722 controller using a three position sunvic valve to control heating/water/both.

When the water is turned on often the heating also comes on even when it is not turned on itself, I think that this happens when the room thermostat requires heat as the water comes on, and does not happen when the rom thermostat is set low and the water comes on.

The sunvic valve seems to go all three positions when it is told to, but the controls seem to be telling it to go to the wrong place... has anyone seen anything similar, or know any more about this??

 

[45yearsagasman]

The 1st thing I would check is the valve spindle. Remove the powerhead and check that the shaft can be moved by hand and observe that the powerhead does actually move correctly to its 3 positions.

 

[Pod1972]

I have checked the valve and can move it by hand, the powerhead moves to all three positions, but for some reason when just water is asked for it moves to the half way setting for water and heat...

 

[45yearsagasman]

You will have to check that the white wire to the valve does not energise when hot water only is selected, and also that the room stat receives no signal.

 

[Pod1972]

The white wire is being energised when hot water only is turned on, but not via the room stat.
I suspect some internal short in the valve, the valve also seems to be defaulting to the fully operated position, i.e. for the heating only, when nothing is switched on in the controller, but in this state the white wire is not energised...

 

[Pod1972]

hmmmmm...

Not a short in the micro switches, or in fact any fault I can find inside the sunvic valve, all components test out as they should.

But the heating is still activated in some instances where water only is supposed to be on .... Help....!!!

 

[Pod1972]

Fixed


Turned out to be the valve after all... perhaps the voltages i used with my meter to test the compnenets do not acurately represent the in use voltages and something was breaking down under load

Valve head replaced system now working