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Because it needs to be fire retardant and expanding foam isnt.
Why ? says who ?Yea you can and thats ok but im saying if its already been done and installed. It would class as an AR? Fire retardant expanding foam is pink i think
How you going to slide a rear exit flue out the way to replace an expansion vessel... obviously the type of boilers that have them behind.
Go the part is obsolete route and get a new boiler lol
Reply to the thread, titled "Can you seal a flue with expanding foam?" which is posted in Central Heating Forum on Plumbers Forums.
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