No hot water unless Ch is on?

[crookie247]

Just wondered if anyone could help?
We've a Worester 24i junior combi boiler. No sure if it's just a chance but took a rad out the other day and since then we can only get hot water from the taps if the central heating is on. Can anybody shed some light on the problem... Thanks very much.

 

[Agile]

Boiler water pressure at about 1.5 ?

Tony

 

[crookie247]

It varies between just under 1 to just over 1 depending if the heating's on. When i first took the rad off it dropped down to nearly 0 so i filled it back up only the reading took sometime to show so it ended up just over 3 so i released some pressure off.
Any help? Cheers

 

[ColJack]

don't know the boiler so it's only a guess but mine would be a stuck diverter valve..

some crud got loose when you topped up and may heve jammed the valve..

with the heating off, do the rads get warm if you run the hot tap for a long time?

 

[Tibbot]

If it's SE version (not Greenstar), it has no diverter. It has a flow turbine (like a switch but spins instead of clicks) which may be faulty. To check switch off CH and check if it fires up with tap on only. CH on will fire the only heat exchanger, as the cold main passes through same block you'll get HW.

 

[Agile]

In that case the DHW demand sensor is apparently failed.

The turbine rotor spins a magnet to induce a signal into the external pickup coils which is measured by the PCB.

If you are bold you could dismantle this and will probably find the rotor has become stuck.

90% of the time you dismantle it and find nothing wrong and it then works when reassembled.

Tony