Vaillant TURBOmax problems

Sladester100

Hi guys and girls

Hoping for some advice on my problem
We have a vaillant TurboMax (unsure if 242/1E or 282/1E as book says both!)

We had a problem before where it keeps dropping pressure and there was talk about diaphragm issues and diverter valve issues but we actually had a bad water leak from a tap water pipe a few weeks later so it was put down to that. Fast forward a year later (and a new kitchen bathroom and hallway carpet thanks to the leak!) and were having issues again.

It keeps dropping pressure and not firing and then as a result is locking out, needing a reset and fill up (using the metalmflexi pipe filling loop below). It's got to the point of having to do so nearly every day now.

In an effort to help diagnose here's some trouble shooting and ideas I've had;

I can't find any leak anywhere, the boiler pipes all seem water tight in all connections, there's no damp or moisture in the cupboard. I've checked all the radiators and all are heating completely without any obvious airlock and have no obvious damp or water leak around them anywhere.

A google and previous thoughts tells me the diaphragm could cause pressure issues or the diverter can cause ignition issues. Seems we have both - but not sure which is the cause and which the result or if both faulty?

For diaphragm a google tells me the pressure could skyrocket when fired; the pressure sat at 1 bar when cold today and then when I flicked the heating onto constant on it rose to just above 2bar within 10 min and has sat there with a gradual small rise of a quarter bar in another 10 so not sure if that's normal or not - doesn't appear to be skyrocketing

Thinking along diverter - when it water is demanded whilst the heating is on it appears to give what's in the system and can be heard refuting to maintain but the pressure of the flow drops noticeably and the temperature fluctuatates to the touch quite considerably whilst it tries to keep up with demand. Not sure if this would point towards a diverter issue or other?

(Incidentally the hot water temp is set to 9 on the dial where the advice in the book is 6 ordinarily yet the water is not scalding to touch and the heating temp also is 9 - the radiators are scalding to touch)

Hope someone can advise!

Alex1983

I would think expansion vessel and losing water out of your pressure relief pipe.

Set the pressure to 1.5bar and run the heating for a while, if the pressure rises up around 3 bar then you need to be looking at the expansion vessel.

macman

What he said. Once the PRV has lifted, they often will not reseat fully, and require replacement, Attach a plastic bag to the PRV overflow for 24 hours to see if it's discharging

Sladester100

Thanks for your replies

The pressure doesn't rise much and definitely not as far as 3 bar, I don't know where the PRV overflow is! I'll have to have a look. I imagine it will be brass/copper rather than plastic like a toilet cistern overflow

Le_Kirk

The PRV will be copper (should be anyway) and will go to the outside. It will just be an open ended pipe so look for that.

I had a problem with losing pressure and tried everything to sort it, no leaks detected, had the expansion vessel repressurised, tied plastic bag over PRV outlet, had PRV stripped cleaned and rebuilt. Finally saw a leak around my filling loop (it was coming from the crimped end) BUT the inlet was turned off and was not passing water from the mains. Turned out it was the non-return valve that was passing water and allowing the system to lose pressure. Replaced with new and all is well - so far!

macman

There are only two pipes venting to the outside: the PRV drain and the condensate drain (if a condensing boiler). The latter will be plastic, running to a drain or soakaway.