Vaillant ecoTec DHW is actually DCW!

First a confession. This boiler was installed 2.5 years ago. And we've never had it serviced. Yes, I'm a plonker and deserve any trouble I'm having (could I have caused any permanent damage?)

It's a Vaillant ecoTEc plus 831.

Just a few days ago I noticed the shower was a bit cool. Even more so today. Just spent the last hour tinkering and experimenting. No DHW from any taps. The actual DHW pipe from the boiler itself isn't warming up beyond tepid, to the touch.

The various diagnositic codes don't report a fault, and the one indicating the position of the diverter valve reports that it's where it should be for the mode it's in at any particular point.

But the actual water is practically cold, as is the pipe, and the diagnostic code that reports the temp of the DHW says 19/20 deg C.

I've tried various combinations of CH and DHW. There's a hot tap close to the boiler so I can turn DHW on and off and see what gives. Cold pressure is the same as ever, and actual flow from the hot taps is fine.

I've tried various things to do with turning off/on and what not. But no joy.

Searches of this forum point pretty squarely to a stuck diverter valve. Even though the diagnostic code says it's in the right place. I assume that means the solenoid (or whatever) is getting current but the actual thing ain't moving. Certainly the temp is being reported for what it is.

Questions:

1. Am I on the right track?

2. How much for a new one? Fitted, that is, I ain't opening up something with gas in it.

3. Any short term fixes to free it up till I can get somebody out to it? Running things hot/cold, in/out shake it all about it, hit it with lump hammer (well, it used to work for starter motors on transits).

You dont say if your heating is working or not?

Assuming it is then it sounds as though your flow turbine has failed

plate h/e probably, 5 minute job to take it out and have a look inside/flush it out.

Be aware this boiler was subject to a recall...I suggest you contact Vaillant first.

Stuck diverter: when you turn on hot tap there would be some heat to the rads.

Does the boiler actually fire when you turn on the tap??

Yes, the boiler fires, the little flame lights up and I can hear stuff that sounds like a fire! I can also hear something that sounds like a valve. But that could be anything though.

So if I wait for the CH to cool down, leave it off, turn on the DHW, if the the diverters stuff the flow pipe for the CH should get warm, yes?

I meant if the diverters stuck, obviously.

Though it might be stuffed too!

OK, with the heating off, and plenty of time to cool down, when I open a hot tap almost immediately the CH flow pipe gets hot, whereas the DHW pipe stays the same temperature.

So is that pretty inconclusively the diverter valve?