Valliant VCW Sine 18T3

[Dabs]

The overheat reset on my valliant keeps kicking in.

The heating works fine but as soon as I turn on hot tap the reset kicks in almost immediately, no hot water delivered at all.

Had several plumbers come around and they all say 'could be this could be that, best to get a new boiler'. A couple said they can try changing some parts but can't guarantee the work as it's so old. Hve been quoted £150+ for trying.

(Had the whole system power flused about 6 months ago, after which the host water was working fine but was very very hot for about the 1st 15 seconds or so before stabalising. Plumber said 'It would be ok after some use'? Has never really got back to normal since but at least I had hot water then, now overheat just kicks in.

Anybody any ideas what it may be?

 

[Dabs]

Can anybody help please or recommend a heating engineer in UB2 (southall) area. Thanks

 

[ChrisR]

SOUnds like it's noticing the flow but the diverter valve isn't doing its thing.
I've got most of one of these complex boilers in my shed. I intended to really work out how it all works one day, but never got round to it, and there aren't many about now though parts are mostly still avaiilable (from conventional sources!).

 

[Dabs]

The temperature gauge is not working now either, but heating is still ok.
Problem with DHW still present, don't understand why cutoff is immediate?

 

[Agile]

Can anybody help please or recommend a heating engineer in UB2 (southall) area. Thanks

Sounds like a job for "ZK" !

As long as I know when he is going so that I can keep my phone off! ( Only joking! )

The diverter valve element is no longer sold on its own and the whole diverter has to be bought for nearly £200.

It sounds as if the calorifier may be blocked !

You will need a very charitable engineer to put in several hours work at this time of year for £150 when a possible part costs more !

A new boiler might be better value for money.

Tony

 

[DP]

Tony, how many diverter elements do you want? Two changed over three weeks.

OP, forget about replacing the boiler. Get someone who knows how the boiler operates. This is one of the very few boilers which now is about 25 years young, with many parts still available.

Chris rightly points out boiler is complex. Many plumbers and (young) heating engineers will not tackle this boiler.

 

[Agile]

Tony, how many diverter elements do you want? Two changed over three weeks.

Chris rightly points out boiler is complex. Many plumbers and (young) heating engineers will not tackle this boiler.

I would like about ten elements!

After I had worked out how it works I would not say that its complex, just a little different!

Tony

 

[ChrisR]

I would not say that its complex

That's because you let your desire to praise yourself cloud your objectivity! As usual!
Count the number of parts in a T3 and compare with, say a Vaillant turbomax plus.

 

[Agile]

Just brought back a PCB from a combi where it was not driving the fan!

That has four electro/mech relays, two SS relays, seven transistors, three 16 pin ICs and one 32 pin IC with four MB of on board ram.

That seems much more complex that the Sine 18 pcb with a 2N3055 and five bipolar transistors!

Now to find the fault on the new board! Probably bad contacts on the fan relay!

Tony

 

[namsag]

I think you will find the fault is quite an easy one . It will be a bit of bull sh#te between pins 7 and 8.

 

[Dabs]

Clearly this is one for the 'pros'. Problem is I can't find one who doesn't run a mile when he sees this thing.

Does anybody know a Heating Engineer covering the Southall area who is 'old enough' (or even a gutsy youngster) who is willing to check this problem. Thanks