The Ideal internal flue tube is suitable for Ideal W 100, Ideal W 45, Ideal W 45 P, Ideal W 60, Ideal W 60 P, Ideal W 80 and Ideal W 80 P boilers, as well as Imax W80 and P gas appliances. A boiler flue is the outlet through which steam and toxic gases resulting from the boiler's normal operation are safely expelled. Different models of flue are chosen to suit the type and location of the appliance.