Vokera Linea 28 - no hot water instead radiators get hot

[kjmcdow]

When we turn on the hot water tap the boiler fires up but instead of water coming out of tap being hot (its lukewarm at best) the radiators start to get hot. I suspect that water heated in the combustion chamber is not being diverted to the secondary heat exchanger but instead circulating in the central heating. The boiler is not cutting out and then cycling back so I am pretty sure the heat exchanger is NOT blocked. Sounds like the diverter valve is not functioning properly. Thoughts on what and how I should check would be greatly appreciated. I image problem could be electrical as well as mechanical.

 

[muggles]

Sounds like a simple stuck diverter valve to me. @vulcancontinental may be able to assist

 

[Terrywookfit]

Remove actuator and check spindle is not sticking/ leaking due to a buildup of $hite. clean with a green pad.
Service kits do not include a new spindle.

 

[ianmcd]

you need a divertor valve service kit, you dont need a new spindle just clean the old one with wire wool or similar then grease it.

 

[kjmcdow]

Any chance it could be a sticking non return valve on the outlet of the primary return from the plate HE? Agile Tony has written for another thread that this could also give the same symptom. I'll start with the diverter valve first however. Thanks for all the replies. A grateful kjmcdow

 

[Terrywookfit]

It's a 2 minute job to unclip actuator and check spindle is moving freely.

 

[ianmcd]

Any chance it could be a sticking non return valve on the outlet of the primary return from the plate HE? Agile Tony has written for another thread that this could also give the same symptom. I'll start with the diverter valve first however. Thanks for all the replies. A grateful kjmcdow

Nope that fault gives completely different symptoms, it is the diverter valve and it needs a service kit, the actuator motor may be damaged by water ingress and as already advised its very easy to check this.

 

[kjmcdow]

It's a 2 minute job to unclip actuator and check spindle is moving freely.

It was indeed a simple enough job. The spindle is moving, but there is some water ingress so ordering a service kit for the diverter value.

 

[kjmcdow]

I am also ordering a diverter front section as apparently it can be very difficult to get out the old seal without breaking.

Read more: https://www.diynot.com/diy/threads/vokera-leaking-divert-valve.256475/#ixzz5FNbcnWK1

 

[kjmcdow]

Thanks for all the input already, but the problem continues and with autumn approaching needs to be fixed. The functioning of the diverter valve appears to be the root of the problem. The diverter valve has been serviced - the spindle now moves more freely. Although there was some water ingress, it does not appear to have been the root of the original problem. It remains that when we turn on a hot water tap the boiler fires up but instead of water coming out of tap being hot (its lukewarm) the radiators start to get hot. The water from tap is only hot if the CH is on.

The actuator works fine. When the CH is on the piston retracts, when the CH off it’s extended, and when the CH is on and a hot water tap is turned on, the piston retracts.

I can get hot rather than lukewarm water through the taps by depressing the spindle manually or by inserting the actuator with a five pence piece at the end of the piston housing so that the spindle is depressed fully. The latter is how we have been getting hot water for the last few months since we have not been using the central heating.

Thoughts on likely source of problem? A dodgy diverter service repair kit or replacement manifold? Crud on the valve seating? And if the latter, what’s the best way to clean?

 

[ianmcd]

when you fit the diverter valve service kit on these, there are two o rings that look Identical and can be fitted either way round but you must use the one with the blue O ring on the rear of the shuttle or you will get the problem that you have