No Central Heating - 2 port valve?

[RegPrescottDIY]

Trying to fix my Mum's heating (now it's getting a bit colder). After doing research on these wonderful forums, I found that if I used the manual override on the 2 port value the heating worked. So the 1st thing I replaced was the synchro motor......no change, no CH on auto but worked in manual position. So then I got a replacement actuator and still the same results. I am pretty sure everything else is working ok as when I turn the room thermostat right down and then move the 2 port to the manual position nothing happens until I turn up the room thermostat and then the rads get hot. I wonder if I have been unlucky and been sold a dead actuator because if the 2 port works in the manual position, doesn't it mean the valve must be working?

Here is the system info (if that helps)

Boiler - Suprima 40L
Hot water tank - Megaflo
2 Port Valve - Danfoss HPA2 (there are 2 of these)
Room Thermostat - Drayton Digistat 3
I couldn't find a central heating programmer but the room thermostat does let you input different temperature for different times of the day, so I guess this does away with the programmer? Wouldn't this then mean the hot water is on 24/7?

Any help would be greatly appreciated

 

[Boilerman2]

Have you got 240v accross the Brown & Blue wire to the heating Valve when heating on and room stat turned up? if so, does the valve lever move over and become free to move without spring pressure being felt?

if answer to these questions is NO, then you have a controls/wiring fault.

if answer to these questions is YES, check for 240v on the Orange wire on the Heating valve, if yes is it feeding the boiler Swl connection
if NO then the actuator head is faulty.

My money is on a Control or wiring fault tho

 

[D_Hailsham]

Was the system working OK last year? If so its unlikely to be the controls.

In normal use, turning up the room stat makes the motor work, which opens the valve, closes the auxiliary switch between the grey and orange wires and turns on the boiler.

Now this is not happening in your case, but the switch will close when you remove the actuator. This suggests that the actuator is not turning the valve shaft enough for the switch to close. This could be due to a sticking valve.

Remove the actuator and check that the valve spindle turns easily by hand (it's not a full circle only 45 degrees or so). If it is stiff, apply a small amount of WD40 to free it. If it's very bad, you may have to replace the valve body. Luckily Danfoss sell the body and actuator as separate parts, so you won't have wasted the money on your new actuator.

The part number should be on the brass valve body.

 

[Agile]

when I turn the room thermostat right down and then move the 2 port to the manual position nothing happens until I turn up the room thermostat and then the rads get hot. I wonder if I have been unlucky and been sold a dead actuator because if the 2 port works in the manual position, doesn't it mean the valve must be working?


Any help would be greatly appreciated

When the lever is moved it opens the valve but it does NOT close the switch ( usually ).

When the motor opens the valve it moves far enough to close the switch.

I have only skimmed throught your post and the replies but thought that may be helpful.

Tony