Vaillant Ecotech Plus 837, now it's the hot water!

[rbalsil]

Must be something about Valentine's day.

Our Ecotech Plus 837 has just developed a fault. The 'stat is demanding heat, the boiler is kicking-in, pump circulating and I feel heat at the very start of the flow pipe. I can also see the zone valve opening. The flame symbol comes on for about 5 sec's then back out. Zone valve closes again.

Does that sound like a diverter?

 

[muggles]

The diverter is in the middle at the bottom on the inside of the boiler. I think they're easy to change, takes me an hour tops, but I've done them before. Check your manual for the part number for your boiler, but plastic ones are 0020020015, around £60, or you can upgrade to a proper reliable brass one for around £100, part number 178978. Beware the Internet, some places might look cheap but might not send the o-rings as part of the pack.

 

[rbalsil]

that's the problem! An engineer came whilst I was at work. He found a stuck 'valve', which he freed up. He reckoned that should be the problem fixed, but has ordered a replacement anyway and will come back to fit it when it arrives.

So, I come home from work to find the house nice and cosy....but now we can't get the how water to heat up. I've checked the temperature setting at the boiler and it's same as it has always been. Best we can get is a 'warm' shower.

So is that part 2 of the same problem...or a brand new one?

 

[The831Bunny]

Was the old DV leaking? If so its more than likely to have taken the PCB out as well. Common fault.

Have your engineer check he's not disconnected the motor from the body. If all OK check the motor action when turning on the mains electric to the boiler. It should motor in then out. If it just buzzes, new pcb needed.

 

[sootydog123]

I had to change both the diverter valve and the pcb on mine. with the front off you can see if the valve moves. Mine didn't just buzzed. When I Changed the diverter valve still just buzzed.When i checked the valve position on the lcd display it was reading as though it was in the correct position,so I made the assumption that the pcb was not sending a signal to the valve. changed the pcb and all is rosy. The pcb has had about 4 revisions and each of the revisions were available on the bay of e for substantially less than retail which is about £200.

 

[rbalsil]

I've no idea what exactly the engineer did. I can say that the heating is now working fine, but we can't get proper how water. I wouldn't have thought it's the pcb as the water is heating up enough for a shower.

Put it this way. I used to be able to fill the kitchen sink and not be able to put my hands in 'cos it's too hot. Now, it's not hot enough. I've checked the hot water temperature 'knob' on the front of the boiler, which is in the '2 o'clock' position it has always been in.

So why the reduction in temperature? I guess I'll have to report it as another fault.