Since the weather turned colder a couple of weeks ago we have been unable to have heating without the hot water being on. Once the hot water reaches the desired temperature, the boiler shuts off and the only way to get heating again is to use the hot water up or to manually override the motorised 2 way valve.

I have tested the motorised 2 way valve on another system and it works fine.
I already had a spare programmer originally changed for visual reasons which I swapped back but no change.
I have rung approximately 15 local plumbers and all seem too busy to come out!

Full spec is as follows:

Potterton Promax 24 HE
Heatrae Sadia Megaflow Boiler
22mm Honeywell 2-Port Zone Valve V4043
Danfoss Randall HPA2 2 Port Valve Actuator
Invensys Drayton Lifestyle LP112 24 Hour Digital Dual Channel Programmer

Any pointers would be appreciated.

Neil, November 2009

sean???????

good answer below though vvvv

ste, November 2009

Turn off power.Disconnect the orange wire of heating m/ valve and put it in a connector.
Turn back on power and turn on time clock for heating
make sure stat is turned up to call for heating
Now take a phase tester and check to see if you have power at the brown wire of heating m/valve???
If so then check if you have power at the orange wire you put in connector for heating m/valve???
Let us know your out come!!!

Raffelect, November 2009

its a diverter fault the system isnt going over to heat and is leaking through heating get the diverter changed it will work then

sean, November 2009

quote: The motorised valve doesn't turn at all when the system starts.

does m/valve get power to brown when stat to max? yes and m/valve dont do nothing? m/valve head fault.

m/valve does not get power to brown, stat fooked. try wire stat out

ste, November 2009

grey= perm live to one side of end switch
orange= switched live from other side of end switch
(made when motor closes switch)
brown=live from timeswitch/programmer to valve motor.
blue=neutral
g/y=earth

ste, November 2009

Where are the grey and orange wires fed from? I've proved the 22mm Honeywell 2-Port Zone Valve so does this just leave the electronic panel in the boiler?

Neil, November 2009

The heating motorized valve is faulty
What is happening is when you turn on your heat and hot water the heating motorized valve is opening (on brown wire) but its taking the hotwater valve to start boiler because the axillaries in heating valve is jammed (grey and orange wires) leaving it cant call boiler
Its a very common fault with motorized valve to fix you need to replace motorized valve head
Hope this helps.

Raffelect, November 2009

The stat clicks when you turn it above room temperature but it doesn't fire the boiler up. The motorised valve doesn't turn at all when the system starts but if you turn it manually then everything kicks in. the hot water is getting to scalding temperatures though!

Neil, November 2009

it has to be motorised valve head not making end switch, maybe spindle on your system not turning that little extra bit to allow head to make switch where on tested system it does?????????

all its not getting is the final power down to ignite so needs the hot water switch to fire boiler which gives heating cos hw's made the switch and valve is opening for heating as your rads heat up.

since your rads heat when you draw hw making boiler fire i would guess room stat is working as the valve to allow heat to rads must be opening.

only guessing without being there with a multi meter to see whats got power and when but why not try borrowing head from the system you tested yours on?????

ste, November 2009

Do you have a stat controling your heating! If so is the light on in it when time clock is on?

Raffelect, November 2009