The one on the right was leaking, been fitted just under 2yrs, removed insulation on secondary H/E (condensing) leak was from S/S to cast join.
Call to Grant Tech ..... new boiler required, and they will honor warenty.
Their service guy came out to confirm and wanted a price for me to change it.
Couple of days later pallet turned up with new boiler minus burner for us to change.
Got it changed in 4hrs fired up, but pressure gauge all over place lots of air in oil!!
Re-made all compression joints in line to tigerloop, both boiler fire valves fitted wrong way so altered so waterproof side up.
Long run to oil tank 50m+, one boiler piped in 8mm the other in 10mm (10mm the one with air in oil) fired up and still air in line, ran for 10-15 mins to clear but no luck.
Connected both boilers to 8mm line capped off 10mm both boiler ran great no fuctuation in pressure, 10bar at both oil pumps when running one or both, sorted.
Dont think it had ran right from day one. 😉