Both hoses rise up from the engine through the bulkhead and down to the connections on the tank. There are no bleed valves anywhere, I disconnected the return pipe/hose at the engine end at the weekend started it up and there was a decent flow of hot water coming from the hose, I also topped the coolant level back up with antifreeze afterwards but it still took forever to get hot water.
I was thinking it may just be that tanks built 12+yrs ago may not be as efficient at heat transfer as modern ones, I assume its just a coiled pipe with no exchanger fins like a surecal type???