Vaillant ecotec plus 831 problems

[Hobo128]

Called out to this boiler, turned hot tap on boiler fires up the modulates down then goes off and water goes cold. Im thinking diverter valve is on its way out. Took out plate just to check and seemed clean enough. Any ideas.

 

[bewsh]

Pump going ok?
You can go through the menus to see which position the d/v is in. They sit in h/w though, so unless its stuck in c/h mode, it should be ok,

 

[arran197]

Check the Ntc sensor resistance. Make sure the ch hasn't been on and feel the flow pipe, if when running the tap it gets hot the diverter could be passing, but generally this would cause the boiler to go to high rate rather than low.

 

[Millsy 82]

If it's modulating then I would say the ntc sensor. If it wasn't modulating then look for a blockage.

 

[Leo21]

There's two ntc,s on these, one to for the display. Swap them over and see what happens.

 

[Matt06]

Try turning cold into the boiler off and see if hot tap still runs

 

[bigads28]

There is a filter on the flow into the plate, if you take out the LWPS you can have a peek in.

 

[negas]

common fault on these is the rubber hoses fill up with rubbish and go hard this stops the water flow from the primary heat exchanger making it impossible to keep up with the demand on dhw heat exchanger causing cool or luke warm dhw. just gently squeeze hoses to check. The pipes can be removed from heat exchanger and cleaned out in a sink at no cost (no need to replace hoses etc).

 

[Sharp Point]

Boiler needs powerflushing, vaillants are an arse for collecting debris and collecting in them poxy little tubes. I wouldn't advocate squeezing the black rubber tube inside the casing to hard as i did this once and really shagged it up, took me a solid day using ds40 and a kamco powerflush to clear it.

 

[negas]

Boiler needs powerflushing, vaillants are an arse for collecting debris and collecting in them poxy little tubes. I wouldn't advocate squeezing the black rubber tube inside the casing to hard as i did this once and really shagged it up, took me a solid day using ds40 and a kamco powerflush to clear it.

Just to make sure it's that but I wouldn't power flush a Vaillant they leak everywhere to start with

 

[arran197]

What is the temperature displaying on the front When this problem is happening and does the boiler fire back up. I would do the simple checks first like the Ntc sensor and isolating the cold. I have had a customer do some plumbing before and the cold and hot were mixing, causing poor DHW temperature.

The rubber pipes are a pain in the bum. They split, get clogged up and leak.

 

[Sharp Point]

Just to make sure it's that but I wouldn't power flush a Vaillant they leak everywhere to start with

Really, I don't think I've ever had that problem and I have installed well over 1000 of them over the years, that's including power flushing them with 'scalebreaker' on various 'local authority' contracts. Mind you they were new boilers....

 

[jtsplumbing]

If Hoses are blocked , better to replace them with the upgraded copper ones.

 

[Leo21]

If Hoses are blocked , better to replace them with the upgraded copper ones.

There silly money, I just replace them with new rubber.

 

[Sharp Point]

There silly money, I just replace them with new rubber.

do you just make your own?

 

[Leo21]

do you just make your own?

No, genuine Vaillant replacements.

 

[jtsplumbing]

No, genuine Vaillant replacements.

Thought they had stopped doing the rubber ones !!

 

[Leo21]

Thought they had stopped doing the rubber ones !!

Ive got a set on the van, I got them about four months ago.

 

[dancinplumba]

Bought some last week

 

[Rabbitman]

Just order the ones from the ecomax range........

 

[Taffman]

Try turning cold into the boiler off and see if hot tap still runs

matt, what would this prove?

 

[arran197]

matt, what would this prove?

It would prove that there hasn't been a crossed pipe somewhere. If the cold and hot have been crossed somewhere, the boiler won't kick outside hot water very well. It's a bit like a thermostatic mixing valve you find in old folks homes. Could also be a faulty mixer tap, washing machine or something like that. If the cold inlet is turned off and the hot tap still run, you know the cold is making its way in somehow.

 

[Matt06]

If a shower valve/ mixer taps etc go faulty then the cold can mix with the hot after the boiler, so turning the cold inlet to the boiler off and run hot taps to check. like Arran says

 

[Hobo128]

Ok Cheers everyone, got to job early morning checked pump to see if it was OK, turns out seals have gone on the pump, changed pump, switch boiler on (purge mode) opened hot tap, boiler fires up then bangs like f#ck and goes off again, checked partical filter which was OK, removed copper flow and return pipes from primary heat exchanger(bit of dirt inside so cleaned out) removed primary heat exchanger from boiler and flushed through with x800 and hose, refitted back into boiler, put boiler into purge mode. Opened hot tap, boiler fires up then flame goes very low only giving luke warm water but no banging and this time stays alight, finally drained boiler down, removed plate heat exchanger and gave a generous tap with my hammer a few times and a flush through with the hose and some x800, refitted it, boiler into purge mode, open hot tap and thank f#ck boiler fired up and gave hot water. So in other word, the boiler was knackered and in need of a big service.

 

[Leo21]

What do you mean by the pump seals had gone? And how could you tell?