Multifuel stove with back boiler keeps tripping RCD

[Deputydigdog99]

Soon as I light the multifuel stove Arada 10.8kw,that runs 8 radiators and hot water.
We had it installed about 10 years ago, by a registered Hetas builder. Had no problems since then until now.
We are getting hot water, that runs on that backboiler,but when the control switch is on, it trips. So we switch the switch off,and use the hot water up.
Hubby who is a engineer, we have changed the thermostat, the pump Wilo Yonus Pica , but onto the same wilo connector ,so haven't changed that connector. It's getting frustrating now, house is getting real cold.Any advice would be welcome.

 

[cross thread]

Check for heat damage to wiring if it’s near any heat areas

 

[Deputydigdog99]

Thank you for your suggestion, hubby is also thinking along those lines, wiring,he's checked the switch,that seems to be the one tripping the RCD. Will check the wiring, that is runs along the chimney line, under some plywood,bit decorating involved. He also going to check the electrical connector to the pump, as he never replaced that as it was a straight swap over for the pump,but didnt come with the new pump.
Thank you so much for your suggestion and time to comment.