vaillant 937

[hammers4spanner]

went to service one of these today and it had a no hot water fault ,

it was insatlled about two years ago but was not used for about 18 months of that time ,

heating works fine but have a s.20 flash up which is no hot water then this changes to a fault code of F.81 and alternates to F.91

pump is spinning fine , i have tried turning temp down then up and it will flash up on hot water for about 5 second sthen goes back to fault status

speaking to vaillant tech help they say its a blockage but the boiler although is two years old has been left unused for nearly all of that so i think blockage although not out question is unlikely????

anyone come across this before with these

 

[lolipop]

If it's only 2 yrs old it will be covered by warranty

 

[The Goose]

There is a housing on the left hand side which has a little screen filter inside. Its basically the return of the circuit from the diverter valve. Could well be this blocked. Also poss diverter valve stuck. If you unscrew the top and pull/push the pin (it hooks into the motor)
Cant remember the fault codes for the shunt pump etc but there is a manual here http://www.vaillant.co.uk/mediaarchive/2013/09/ecoTEC-plus-937-installation-service-manual.pdf

 

[Alex Pelton]

hate to say this, but been to one of these in the past customer saying it's not working properly. The installer had not connected half the wires up. the boiler comes in two parts with fiddily connections onto the pcb from one part to the other.

 

[justalex81]

As above. it's basically an 837 attached to storage vessels. loads of plugs to connect up. If you can't get it going, tell the customer to phone vaillant and tell him it just started happening. do not tell em it's been idle for a year!

 

[novicegas]

bet the diverter valve is stuck, has a cold feed filter been installed? Vaillant know that their dv stick hence the request for some sort of sesi put on the incoming.