Vaillant VCW 242e

[Waterworxsw]

Hi, got a little problem with a VCW 242e. And after speaking to Vaillant tech guys I'm even more in the dark.

Basically, I got called to look at this boiler due to the central heating being very temperamental, if it wouldn't fire up then the tenant would turn the hot tap on then off and this would then fire up the heating. I spoke to Vaillant and did some pin testing with the tech guy over the phone and he came up with the diagnostic of a faulty motherboard. This was replaced.

Since then the boiler will overheat and go to lock out when running on '9', run the boiler on '6' and it works fine, modulates as it should do. spoke to the Tech guys after checking the NCT and overheat stat and the came up with 'sticky gas valve'.

Just wondering if anyone has any suggestions as to the solving the problem, I don't really want to replace the gas valve if it's not faulty, and to get various different answer from Vaillant Tech regarding the same problem is a little disheartening.

And just to add a little spanner in the works, the timeclosk, it seems that with the mechanical timeclock connected the boiler even overheats and goes to lockout when set on '6'.

Many thanks

Al.

 

[chrishutt]

"Sticky gas valve" sounds an unlikely explanation. I'd be more inclined to expect some scaling up of the main heat exchanger - these boilers are getting on a bit. If the overheat only arises on the highest thermostat setting then just run it at no.6. It's not dangerous since the overheat will protect the boiler.

As for the time clock, there's a good chance that this is wired up incorrectly, which might be contributing to the problem. The load switch on the timer should be connected to terminals 3 and 4. Quite often the switched live will be taken from the permanent live (e.g. supplying the timer motor) which by-passes the boiler controls.

 

[Waterworxsw]

Cheers, I tested it and left it running on '6' for a good couple of hours Friday and it was running ok, the tenant knows not to wack it upto '9'. Just seems odd getting 3 different diagnoses from Vaillant tech.

 

[Agile]

I really think that it is the boiler engineer who should be capable of diagnosing the fault on site without having to call the manufacturers three times to ask them what they think is wrong.

Its very difficult to diagnose a fault over the telephone, particularly for most manufacturers who dont use experienced boiler engineers on their help lines.

Tony

 

[Waterworxsw]

Tony, I just thought it was odd to get 3 different answers from a boiler manufacturers technical department, who in theory should know the ins and outs of their boilers. I appreciate it's not the easiest to determine a fault over the phone hence why I was stood in front of the boiler 'testing for them'.

I've been in the trade nearly twenty years (obviously not as long as others) and can repair most faults with gas appliances and heating systems, I don't claim to be an expert on everything and the Vaillant 242 along with, for example, the Chaffoteaux Celtic FF are 2 that can sometimes baffle me. That is why I phoned Vaillant for advice and also why I posted here, hoping to get assistance from gas engineers with more experience of these boilers.

Cheers

Al

 

[bengasman]

Nothing wrong with calling the technical helpline, that is what they are for. Intermittent faults can be a real pain and very difficult to spot sometimes unless the client is willing to pay you to sit there for a day and watch what is going wrong.

 

[Agile]

An advert I saw for Potterton technical helpline operators in Leamington required "no previous experience".

They are not highly experienced boiler repair engineers and they are only trained a little in common faults like blocked heat exchangers and faulty NTCs. Anything more and they will not have any clue.

They are not CORGI registered and have mostly never ever repaired any boilers.

Thats not surprising when a typical salary is only £12k to £16k.

Tony

 

[Rob]

They are not highly experienced boiler repair engineers and they are only trained a little in common faults like blocked heat exchangers and faulty NTCs. Anything more and they will not have any clue.

I think thats a bit unfair. Most know their boilers pretty well. I use them for specific information rather than 'what do ya think the problem is'

No dis-respect to OP though. I avoid the VCW's although most faults are no different to most boilers. i.e block PHE, diaphragms etc