Issue with vaillant plus 630

[I-kal]

hey guys a customer called me up and asked me for my help on a peculiar job, he has a vaillant ecotec plus 630 which always stays on so there’s a demand even though controls are off and non of the motorised valves are sticking , he says it was installed like this from day dot. The boiler only has zone valves for the underfloor heating, before I go there I was wondering if someone could shed some Light on the matter. Maybe it’s been wired incorrectly ? Maybe a simple thing as link wire has been left in the boiler ? Any other ideas I should look for. Thanks

 

[Harvest Fields]

Wired in wrong? 2 ports? UFH wiring? Timer?

 

[Burger]

https://www.vaillant.co.uk/download...d-maintenance-0020244997-02-1-pdf-1413953.pdf And lookup the wiring - for underfloor heating it mentions the burner off on the pcb. Also check the live monitor status code, it might tell you which demand is being created.

 

[EvilDrPorkChop]

Has the 24v link been removed? If this is still in it'll just fire all the time (You know this by the radiator symbol on the front) Remove the RT 24v link and it'll just use the 240v RT switch live as a demand.

 

[I-kal]

Hey guys just a quick update, so went to the property and it looks like the hot water cylinder stat was keeping the boiler on because it was wired directly to the programmer ‍♂️. I can’t imagine why someone would do this. After a little rewiring it’s sorted. Appreciate the help. Many thanks

 

[I-kal]

Oops seems like a spoke to soon, customers calling me up today saying boiler hasn’t fired up it worked all day yesterday but today morning hasn’t fired up. When I initially wired everything up the boiler didn’t fire up I then took readings with multimeter to make sure it was wired correctly and the boiler when flipping the Pcb up worked. I recon you the boards dodgy ? I don’t want to second guess my wiring as it worked several times on and off on tests last nights

 

[Burger]

Oops seems like a spoke to soon, customers calling me up today saying boiler hasn’t fired up it worked all day yesterday but today morning hasn’t fired up. When I initially wired everything up the boiler didn’t fire up I then took readings with multimeter to make sure it was wired correctly and the boiler when flipping the Pcb up worked. I recon you the boards dodgy ? I don’t want to second guess my wiring as it worked several times on and off on tests last nights

It might be something in that area then, loose connection to the board? - double check your wiring, and check the voltage. Is the flex tight? If it is it might be enough to work a connection loose.

 

[I-kal]

Ok will check for loose connections etc. I was thinking if I wired out the control side of things on the boiler and it fired up it would more or less rule out Pcb board if it fired up? Then I would have to look at loose connections etc especially if it was working properly all day yesterday.

 

[Burger]

Ok will check for loose connections etc. I was thinking if I wired out the control side of things on the boiler and it fired up it would more or less rule out Pcb board if it fired up? Then I would have to look at loose connections etc especially if it was working properly all day yesterday.

Not necessarily, I’ve had, esp Vaillants, fault codes that are resettable, which firs up then goes off, but is usually indicated with a fault code, eg F61.

 

[I-kal]

So went back to the house, checked to see if the controls were sending 230 v to the boiler which it was, then looked at the boiler but it still wasn’t firing up, I was about to leave the property as it seemed the Pcb was faulty and it came back on again so surely
Has to be a intermittent issue on Pcb

 

[Burger]

So went back to the house, checked to see if the controls were sending 230 v to the boiler which it was, then looked at the boiler but it still wasn’t firing up, I was about to leave the property as it seemed the Pcb was faulty and it came back on again so surely
Has to be a intermittent issue on Pcb

It could be, but could also be another wire, microswitch, etc. Let’s be honest, you don’t want to fork out approx £245 for a pcb, when it could be something else?