No hot water - but central heating works

[simoncollins48]

Hi. I have gas central heating and water and the water has stopped heating.

I have a cylinder in my airing cupboard and two 2-port motorised valves, one which seems to control the central heating and one which cntrols hot water. I've changed the thermostat on the cylinder and have checked that both valves are operating by turning on CH and HW separately and then moving the lever on the valves to "manual". Both times there was no resistance, indicating that the valves are opening with the motors.

I've tried turning the cylinder stat right down then switching on the HW at the electronic programmer. Then turn up the stat and when it clicks, the boilder fires. However it only seems to stay on for a few minutes then turns off - well before the water has got hot and the stat has kicked in.

Anyone got any ideas as to what might be wrong?

Thanks for any help or advice.

Simon

 

[kevplumb]

water in the header tank

 

[Boilerman2]

Does the pipe work at the motorised valve get hot?? if not check the header tqank in the loft (the small one) it should be about half full of water, are you sure that the circulating pump is working??

What make & model boiler do you have??

 

[simoncollins48]

I've checked the header tank and it's half full. My boiler is a Stelad Group Ideal Elan 2. (?)

I'm not sure what the circulating pump is, but if it's the central heating pump then that seems OK. All the rads throughout the house get hot when CH is on. It's just HW that's acting up!

 

[kevplumb]

try locking the hw valve open with the lever

 

[simoncollins48]

Thanks Kev. Have tried opening the valves manually but same problem - boiler stops after a couple of minutes. Any other thoughts?

Thanks

 

[kevplumb]

vent points near the cylinder View media item 11360