Maintenance of diverter valve.

[IanDB]

This is closely related to several posts. My motherin-law's Vaillant combi boiler (3 years old) heats the radiators when the hot water tap is turned on and there is only like warm water at the tap.

How maintainable is the diverter valve? I.e. can you do anything to it without taking it out, if you take it out what can be replaced on it? I believe this item retails at around £65 so I don't want to have to get a new one if I can help it.

this is the item I'm talking about.

Any advice would be greatly appreciated otherwise I'm just going to have to get in amongst it next time I see her. Thanks, Ian.

 

[weargas]

the diverter valve has a replaceable actuator that can be changed with the minimum of fuss. whoever manufactures these valves for vaillant tend to tighten the reatining ring on very tight so you'll probably need something to loosen it but hand tight should do for replacenment. the interior of the valve may be the problem though. it's basically a rubber ball fixed to the end of the shaft that blocks/opens ports.
the rubber may have hardened making it only partially block the ch port.
the shaft may have become stiff in moving up and down making it too difficult for the actuator to push/pull
the ports may have become blocked/fouled.
you can remove the actuator and with some needle nosed pliers pull and push the shaft to see how free it is.
when this boiler first came out i had tried to "service" a valve by stripping it down, cleaning and greasing the pin and cleaning the port faces. when i put it back together it was no better. changed the valve and it worked perfectly so i don't even bother trying to repair them. they're easy enough to change, 2nuts, 1 clip.


i remember talking to the vaillant rep at interbuild 2000 and he was so full of himself about this valve, how you'd never have to change the valve or drain it down, just replace the actuator.









bullshit. test a boiler before making claims.

 

[IanDB]

Weargas, thanks for the advice. I'll let you know what I find.

i remember talking to the vaillant rep at interbuild 2000 and he was so full of himself about this valve, how you'd never have to change the valve or drain it down, just replace the actuator.

Isn't it always the way!

Cheers, Ian.

 

[IanDB]

My mother-in-law is a pensioner on income support and had her system installed under grant a few years ago. When I wnt to visit her (she lives 150 miles away) I found that she'd been without hot water for 5 weeks. Despite repeated phone calls to the helpline no-one had come to see her. So I had a word with them and someone should be out today.

It turns out that she is covered for the replacement of the valve. I had a look at it and it was exactly as described. The actuator was working but the shaft was as stiff as anything and I expect that's where the problem lies. At least I got her some hot water for the weekend.

Weargas, thanks again for the advice.

 

[ChrisR]

I posted this elsewhere some tjme ago. I wonder if the "newer" DV's are in fact showing the same fault(s) as the earlier ones?:

>>Common problem on the model apparently, until the slightly later ones, where a different DV was fitted.
The top end of the DV has a motor in the black plastic part to operate the central shaft. On the earlier DV's, some have a number in white on the black plastic part which starts with an "A" (though this one didn't). Also on earlier ones there's a number stamped into the brass body of the valve which is visible from the front of the boiler when the valve is in place. (In my case its a 4 digit number in figs about 2mm high).
So if you can see the "A..." number on the head or a number stamped on the body it's an early one.

The later DV's have a number starting with a "B" on the BACK of the DV so you can't see it from the front when fitted.

The main problem is that the ball sticks. Typical symptom is that the rads get hot when the boiler does its hot water preheat - ie with no user activity at all. <<