Leaking Vaillant ecoTEC plus and pro Diverter Valves

Firstly, in our experience (covering North West England since 1992) a leak on a Vaillant Diverter valve ecoTEC plus or ecoTEC pro boiler, is actually quite a rare fault or failure to have, taking into consideration just how many ecoTECs there are actually out there!
This is contrary to what we are led to believe.

Now, I know, if your own boiler is suffering from this concerning problem and water is dripping out of the Diverter valve down on to your work surface, well you will probably, find this very hard to understand.
There are possibly many hundreds of thousands of Vaillant ecoTEC combi boilers out there, and only a very small fraction, of these excellent boilers actually ever develop a leaking fault from the Diverter valve!

Vaillant ecoTEC Diverter Valve

We here at Glowcare, being Vaillant’s North West service agent for Gt Manchester, Cheshire and surrounding areas for over 20 years, have found that approximately over 95% of the ecoTEC boilers, never develop a leak on the Diverter valve, confirming that the valve itself is not the real cause of the problem. So if the valve is fine under normal circumstances, what’s causing these few to leak?

In our experienced opinion, it is more or less always the case, that dirty, contaminated water in the heating system causes a brown coloured staining to appear on the piston rod in the Diverter valve.
This allows system water over time to drip past the small O-ring seal in the valve resulting in the leak.

Sometimes, when carrying out an Annual Service on a Vaillant ecoTEC plus or ecoTEC pro boiler, if the water in the customer’s heating system is contaminated or contains very dirty water, the brown staining marking on the Diverter valve piston rod, may well have already begun to show, but not have yet started to leak past the valve O-ring seal.

In our opinion, the black plastic-bodied ecoTEC Diverter valves (out of the two different types of valve) probably get more leaking problems with them, than the brass valves do. The plastic-bodied valves are mostly fitted in the Vaillant ecoTEC pro 24 and ecoTEC pro 28 boiler models, with the ecoTEC plus using both types of valves, on different models within the plus range. The plastic valve typically being on the smaller ecoTEC plus 824 and ecoTEC plus 831, with the brass valve being used on the bigger kW outputted ecoTEC plus 837 and ecoTEC plus 937. There are some other variations to this, but basically that’s pretty much it.

As a Vaillant ecoTEC owner, one of the main reasons you may have chosen to buy Vaillant, is that they are rated about the best domestic brand of boiler you can possibly purchase, hardly ever suffering any problems or breakdowns throughout the life of the boiler.

In our experience and for whatever reason, lots of people don’t actually ever bother going down the route of system water investigation!
This could be because they just can’t be bothered to do so, or they just might be very busy people, not having any spare time to get a plumber in to quote for a system flush. It also could be that they are planning to move house in the next couple of years, and will just leave it!


Intermittent ecoTEC Leaking Diverter Valves explained

Occasionally a customer will say that they have had dripping or leaking water before, from the area underneath where the boiler’s Diverter valve is positioned, but now it all seems to have cleared up and is not leaking anymore.
It would be great if the leak had permanently gone, but alas, unfortunately and in all probability, the problem with the faulty leaking Vaillant ecoTEC Diverter valve has just gone away for the summer!
This is because in summer, when the heating is not being used and the boiler is mainly in hot water mode, this puts the position of the piston rod in the valve, in a new or different position.
In this other position, a different cleaner part of the piston rod (which has no brown staining on it) makes a good clean watertight seal with the O-ring seal. This results in no water being able to leak out, but this of course is only temporary!
When the heating is put back on again in the Autumn, the piston now moves back to it’s more normal position, and unfortunately, the Diverter valve will almost certainly start leaking again, resulting in a new Diverter valve still needing to be replaced to resolve the leaking issue.

The good news is, if you prefer to, you can just change the Diverter valve in the ecoTEC plus or pro boiler, without investigating the dirty system water issues (ideally though you really should think about getting the dirty system water issues checked out). This is because with a brand new Diverter valve fitted, you should get a good few years down the line (time wise) before, any signs of leaking problems, show up on the Diverter valve piston rod again.

So, if your choice is to just replace the leaking Diverter valve, we here at Glowcare can carry out the replacement for you.

We cover most areas in North West England. Glowcare are Vaillant Group’s dedicated service agent for the North West of England, Est. 1992. We carry both the brass and plastic versions of the Diverter valve, both with a 1 year guarantee.

Glowcare can be contacted for a Fixed price Repair to replace your leaking Diverter valve, on 01244 880725 or 07789018775 or Email info@glowcare.co.uk

Thanks for reading!


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