worcester hiflow 3.5 ch not working

[cornerwaysuk]

Hi, I have a worcester 3.5 hiflow. The hot water side runs great and the central heating side did do until yesterday when it failed to heat the rads in the morning.
On looking at what is happening i found that the burner ignites ok but doesn't stop on long enough to heat the rads. the pump seems to be working, the out pipe to the rads does get hot the return pipes remains cool. The rads do get warm but don't heat up. eventually the system remains cold cos the boiler does not come on at all.
The heating temperature dial on the front of the boiler when cold is set low, each time the boiler fires up and then goes off its in line withe the setting on the heating temperature dial. if i then move the dial it clicks and the boiler fires up and then stops, i then have to move the dial till it clicks again and the boiler fires up. This goes on till i cant do it any more then it takes ages for it to start agan thus no heating. As i said the hot water works fine.
Can anyone advise me as to what parts i might need to replace or how i can check for parts not working? Is it likely to be the heating temp switch? motorised valve? thermocouple? Any help is appreciated! Cheers Eric Clegg

 

[PEDANTICVINDICTIVEMAN]

Not particularly familiar with these, is there a room stat fitted and got accidently turned down, check the diverter valve, is the heating full of water and all valve turned on.

 

[cornerwaysuk]

Hi, The system does not have a room stat it is all rad stats. There is water in the system all rads have been bled. don't know how the diverter valve works or how to check it. any assistance would be appreciated. cheers eric

 

[doitall]

only got the book for the hi-flow 400 so would be guessing.

are the lights doing anything like flashing fast/slow.

 

[cornerwaysuk]

There are no lights to flash! the only visible thing that has any lights at all is the timer display. The pilot is on no problem the boiler fires up for water no problem, it fires for heating but wont stay on its like the boiler is getting hot and it switches off, then cools down and will switch on again, it doesnt stay on anytime to heat the rads. cheers eric

 

[corgigazza]

this boiler has a 3 port valve on the middle L hand side. check this open when ch selected if not check power to it and replace syncron motor or valve complete. note; valve is three way diverter not mid position

 

[COG]

As Corgigazza said but tru to replace only the motor its only two screws ,a bit tricky but a lot simpler than replaceing the complete valve as the replacement supplied is differant from the original and can be a sod to fit.

 

[cornerwaysuk]

Thanks for the info, i know this will seem stupid but how do i check the valve is open? There is a lever that i can move manually but i don't know what happens when i move it? any help please? it is getting current! Cheers eric

 

[ollski]

when you move the lever across it will open the ch port and your heating should work, if it does you will need a new synchron motor, if not new head.

 

[cornerwaysuk]

Well i have moved the valve manually and the heating now works. so i guess that means it needs a new motor! Does that mean that the hot water wont work as i have held the valve open so the heating works? Thanks for everyones help just one more thing where is the cheapest place to get a motor from for the valve? and are they all the same? cheers eric

 

[jogger321]

I have exactly the same problem ..apart from the fact the diverter valve mechanism is clicking..it looks like a brass toothed sprocket has worn on the mechanism...How do you replace the valve on this boiler...I'm worried about flooding the place..Are there any drain valves on this boiler or what is the procedure for replacement???

Thanks