Hi I have a customer who has the tank and cylinder in the loft. The problem they have is that they only have a small cylinder in position and they are not getting enough hot water. I cannot fit a bigger cylinder in due to the height of the header tank (And it cannot go up any more). I have suggested a horizontal cylinder then we can gain double the literage but the price is a bit step. Dont mention a combi because they have just had a new boiler installed. They have asked me to add another cylinder on to the system so they would be working side by side. Does anyone have any info on this set up and if it can work as I cannot see how. Antother plumber has quoted to do this set up. I cant see how it would work.