Was looking for a manual last night for you to clear up this flue issue. It seems their website only has the user manuals on their website. I think these are made by Ideal but there does not seem to be any literature on the Ideal website either. The Pro-Combi website is:
Home - Pro Range or telephone: 0116 256 7380 although these guys could just be a retailer I am not 100%
Got through and spoke to Pro they told me it shouldindeed have a horse shoe clamp on it and sealant is not recommended buy them.Spoke to Gas Safe they said as long as it’s not spilling and it’s not it’s anAR they are sending someone out as i suspect RIDDOR will as iv filled it withthem. Unfortunately for the customer one of the elbows above the boiler failedand dropped the hot water over the boiler this morning made a real mess. Outcomeis ive told them I won’t refit that boiler I want to but one in that I knowwhere it comes from ect good thing is they managed to stop payment to theprevious installer via bank So there’s plenty left in the kitty to pay me lol