Oil Fired Worcester Heatslave diverter valve gone duff

I apologise in advance if this has been covered before, but I've spent half an hour searching posts and havn't found anything yet.

I woke this morning to a relatively cold house, though still with hot water to taps. It appears that my Worcester Heatslave oil combi boiler has decided to break down 5 days before christmas, nice timing !

On investigation inside the boiler, with the first apparant thing being a strange buzzing noise, I pretty much decided that the diverter is not diverting anymore. I've manually pushed a lever accross that appears to have engaged the heating again. Which is where I become confused.

If setting the diverter manually to allow heating and apparantly hot water at the same time, what is NOT going to work properly ie what are the implications ?

I've also done some reading on the topics here and accross the web and it appears most diverters are fixed by replacing some rubber valve that controls the feed based on demand. Ok, I understand that, however, is my diverter completely different then ? It has an electric supply and was buzzing like a servo was about to fry !

I've contacted the guy that normally does repairs, but he's up to his kneck in it until well into January, so, I'm trying to figure out if I can repair this and to what extent, parts need replacing.

Cheers for any help in advance.

It's been covered before, but the search tool is useless. Admin please note.

The diverter is a Honeywell 3-port valve (4073A) and you probably need a new actuator, available from Plumb Center as a standartd part which you will have to join the cables, or Part Center which would be the pukka bit and you can plug it in to the circuit board. Expensive.

You might need the manual though, as it's a pain to get the bits apart to replace it.

Thanks for replying Oilman.

I take it, that the actuator is the silver box with the wiring coming out of it that sits on top of the valve assembly ?

Just to add some new observations.

Having got home from work, the heating had been on and was in the process of going cold. I've now discovered that the heating only seems to kick in if a hot water tap is running or the boiler is below the preset temperature ie after the hot water tap has been run for a while or the heating has initially kicked in.

I'm just adding here so if anybody reads this and it sounds familiar they can throw their tuppence in.

Is that with the lever moved over to the manual position?

Yes. I had pushed the lever into the manual position this morning and left it there.

It may be just the synchro motor in the actuator, but if diagnosing that is beyond you, you will have to replace the actuator complete. It's the heating side that's not workking. If you have a room stat (fat chance) put the lever in the auto position, and operate the room stat. The lever should be floppy for the full travel. If it is, then it's the complete actuator as a switch has gone, if it's stiff, then it maybe just the motor.