i let mine tickover for 3-4 mins (first job so from cold) then i start cleaning cleanest parts of room, as they dont require all the heat to clean, its pretty much coming through hot as i get to dirtier bits, course bit slower the more lenghs of solution im using, but hot before i've finished first room, i honestly could'nt complain about the heat, it's supprised me just how good it is considering its a heat exchange.
maybe it's been improved, redesigned? since yours?