Well good news, the water heater gas system and auto igniter works just fine. Bad news, the boiler has rusted on the left side resulting in a gas leak at the end of the boiler which results in a flame where there shouldn’t be one.
Boilers (the rectangular stainless part with the gas jets in it) are around £50 and standard off the self spare parts. The entire brains of the system can be removed from the roadside and the boiler replaced easily.
The rust problem is due to heat, the proximity of water and exposure to the elements as this all faces the roadside. I am going to try a repair initially as the boiler box is not under any pressure, just heat. If the patch I am going to try with some exhaust epoxy and spare metal sheet doesn’t work I’ll bite the bullet and buy a new one.
The water tank needs to be pressure tested, the wax thermostat that acts as a safety preventing overheat also needs testing and then she needs a clean up and can be installed into the van side ready for the pipework.