DIY repair Vaillant VCW 180 XEU

[koala156]

Hi all,

(I don't live in the UK and English isn't my primary language; however I'm hoping I can get help here as this forum seems to be the best one for Vaillant-related DIY questions)

My story:
in the apartment which I own we have a Vaillant VCW 180 XEU boiler for both, hot water and CH. Last year we began to experience some troubles with the heating - the boiler would work very irregularly, sometimes heating-up, sometimes not. Hot water worked reliably.

A few days ago we tried using the CH again and it was a no-go. Hot water works just fine. We called a Vaillant-certified repairman who told us that we either need a whole new installation rounding up to 3k or a major repair of our boiler. BUT he also announced that Vaillant does not supply parts for VCW 180 anymore and that he won't be fixing our boiler using old/used parts (probably due to warranty/insurance issues).
He did however give us a list of broken/needing-replacement parts (the list is in German, I hope translation makes sense):

- Priority Switch Valve #12-684
- Servo Pressure Regulator #05-0164
- Electronic Regulator (PCB) #25-2947

[ to note here: the main pump was replaced 3 years ago ]

I was able to find all these parts on eBay and they are coming in a few days. As we aren't able to find anyone who'd install these parts for us I'm thinking of doing it myself. To be frank I don't have any formal engineering education but I know how things work and also that threading on gas pipes goes the other way. I have repaired car-engines, know how to weld and generally good with electronics. I have a good toolbox too

Now, can you please give me some hints and advices on how not to make things worse and to succeed in my undertaking? I know it is a risky matter, so I don't need to hear about it again; I wouldn't be doing all of this if I could cash-out for a new installation. I realize though that I can't be running a boiler from 1989 for that much longer, but during this winter it has to work!

- Do I need any special, Vaillant-specific tools?
- Do I need to care for torque specs when screwing things back together?
- Shall I be replacing seals when changing the above mentioned parts?
- How to properly refill the system after it's put back together?
- Any other parts which might be good to replace once I'm at it?

Greeting to all from Berlin!
Daniil

 

[Gasguru]

Your boiler model doesn't appear to have been sold in the UK but is similar to the CombiCompact VCW 242EH and variants. The main difference is your version is open flued so potentially far more dangerous that our fan flued and balanced flue models.

Forget repairing the boiler yourself, most in the trade haven't a clue how these work, although the basics are very simple...find someone that knows them, can't be that hard in Germany.

It appears you have your cowboys too. I'm doubtful the list of parts you provide have anything to do with the heating not functioning.

Vaillant still supply many parts for the UK equivelent models.

I suggest you have a look at the diverter valve on the right hand side of the boiler. Under the clear plastic cover check the diverter mechanism is moving suffiicient to activate the microswitches. Sometimes a little nudge will free up the valve since it has only been operating in hot water mode throughout the summer.

 

[koala156]

hi Gasguru,

Your boiler model doesn't appear to have been sold in the UK but is similar to the CombiCompact VCW 242EH and variants. The main difference is your version is open flued so potentially far more dangerous that our fan flued and balanced flue models.

Forget repairing the boiler yourself, most in the trade haven't a clue how these work, although the basics are very simple...find someone that knows them, can't be that hard in Germany.

It appears you have your cowboys too. I'm doubtful the list of parts you provide have anything to do with the heating not functioning.

Vaillant still supply many parts for the UK equivelent models.

I suggest you have a look at the diverter valve on the right hand side of the boiler. Under the clear plastic cover check the diverter mechanism is moving suffiicient to activate the microswitches. Sometimes a little nudge will free up the valve since it has only been operating in hot water mode throughout the summer.

thanks for the response,

actually 'diverter valve' is exactly what I roughly translated as 'Priority Switch Valve' - that's the part which I'm getting new. The repairman who looked at the boiler said that this valve is most likely causing the problems. I did try 'helping' it move already but it just stays disengaged at all times and there is no way I can push it back in.

I guess I will attempt to replace the valve tomorrow, it doesn't seem to be too difficult to do.

Any hints?

 

[Gasguru]

The diverter is very rarely a problem.

The servo valve directs differential pressure across the diverter diaphragm. If the diverter is sluggish it is normally due to the servo valve or control tube issues (blockages in the tubes, restrictor blocked etc)

 

[koala156]

The diverter is very rarely a problem.

The servo valve directs differential pressure across the diverter diaphragm. If the diverter is sluggish it is normally due to the servo valve or control tube issues (blockages in the tubes, restrictor blocked etc)

I'm getting a new servo valve too. By taking both off I will be able to check the tubes for any blockages, right?

 

[Gasguru]

Use the search...plenty of previous postings.

 

[Agile]

I am slightly amused that in the land of the Vaillant you are still unable to get your boiler repaired and just like the UK you are being told to get a new boiler!

Geoff has explained what is probably the cause of the fault. I would also take the view that your boiler is best repaired by a person skilled in mending them. Probably called Ein Boilermakenitwerkenheir or something vaguely similar.

I have never repaired a boiler in Germany so dont know about gas fittings but in the UK only bottled gas has left handed threads.

Tony