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Sandeep89

Gas Engineer
Nov 18, 2020
60
4
8
Member Type
Heating Engineer (Has GSR)
Just serviced a Vaillant Ecotec Plus 824 and after putting all back together and filling up got some issues.

The burner keeps modulating between high and low ever few seconds when running hot water. I checked the inlet pressure and all is within parameters per MI.

Heating came on for few seconds and then burner cut out and boiler went into pump overrun. After this heating has stopped working, shows S.0 no heat demand even with the stat linked out and running heating from the boiler. The heating symbol is displayed on the boiler but the symbol just stays solid.

Its had a new gas valve fitted few months back and a refurbished PCB. Could it be that the PCB has gone again.
 
Did you remove or unplug anything while servicing?

Removed ignition lead, fan connector and gas valve connector but have double checked and all connectors are back in securely.

Other than the service and isolation the gas service valve on the boiler didn't do nothing else
 
How old is it? Sticky diverter? Plug not fully home?
It is around 6 years old has recently had a new gas valve and a refurbished pcb board.

When you say plug not fully home do you mean the ignition lead plug?
 
Sounds like no flow? Did you isolate the flow and return? Is there a filter fitted?
 
Sounds like no flow? Did you isolate the flow and return? Is there a filter fitted?
Yes I isolated the flow and return and then unisolated before filling up. There is a Magnaclean pro 1 which I isolated the valves and then unisolated after cleaning the filter.
 
It is around 6 years old has recently had a new gas valve and a refurbished pcb board.

When you say plug not fully home do you mean the ignition lead plug?
No, meant the one to the diverter motor. It normally makes a noise on start up, to listen out for.
 
Did you open both flow and return? I’ve done that by mistake before now. Or close them off again?
 

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