Heating no hot water

[KingDoey]

Evening all, your thoughts please...

Friend of the family had trouble with heating last week. System is y plan. Went round no water in system.

Cleared blocked cold feed, filled system and tested all good.

Called today no hot water. Went to look. Call for hot water and mid position valve moves over correctly yet pump does not start.

Switch to heating, valve moves over and boiler fires all good. Put both on, valve moves to mid position, boiler goes out. As soon as hot water is selected regardless of what heating is doing the boiler shuts off.

Cant be cylinder stat or programmer could it? And have power off orange on mid position valve. So surely not that.

Stumped on this one anyone have any ideas?

Thanks in advance!

 

[Rob Foster]

check pump

 

[KingDoey]

check pump

Pump is sweet as stated comes on with heating?

 

[Aire]

I'd be testing power to and from tank stat. If I remember correctly, the 3 ports resting position is to feed hot water so when you call for hot water, no power is sent through the 3 port, it's goes from the programmer, through the tank stat and back to boiler and pump.

 

[KingDoey]

I'd be testing power to and from tank stat. If I remember correctly, the 3 ports resting position is to feed hot water so when you call for hot water, no power is sent through the 3 port, it's goes from the programmer, through the tank stat and back to boiler and pump.

Good shout Craig, I will check that. I overlooked it as assumed it was sound if valve moving over.

Would that affect it when calling for both though? So when heatings on, if you then put HW on aswell the boiler and pump go off

 

[Aire]

I think when calling for both, the programmer sends power to room stat, then to 3 port which motors it over to mid position, and thats it, a switch live back from the 3 port isn't necessary as the boiler is already powered by the tank stat. Its only when calling for heating only that the valve motors over fully and sends power down the orange wire.

 

[KingDoey]

I think when calling for both, the programmer sends power to room stat, then to 3 port which motors it over to mid position, and thats it, a switch live back from the 3 port isn't necessary as the boiler is already powered by the tank stat. Its only when calling for heating only that the valve motors over fully and sends power down the orange wire.

Cheers mate

Will try the cylinder stat tomorrow.

 

[SJB060685]

As Craig says. When calling for both the white wire is internally providing power to motor through a diode which is providing pulses of dc power to motor, enough to hold in mid position. Like he said for hot water only check feed from programmer to cylinder stat to boiler. What should happen is grey wire (HW OFF) de-energises, valve if not already will spring return to HW position, power from programmer goes through stat and to boiler, providing it’s all good.

 

[KingDoey]

Cheers chaps

Just to update it was a loose wire from the cylinder stat in the wiring centre. Wasnt obvious as still looked like it was in place.

All sorted