Daniel Witherstone
Sounds like a plan Chris. Only make sure that you have adequate joist support in your attic to site a cylinder. A standard 120L steel cylinder could potentially weigh in excess of 140kgs once filled with water. For example, If I were to do it in my own house I couldn't as I have only 70mm x 70mm beams supporting my upstairs ceiling and would not be sufficient to support this weight safely. The other thing to consider when siting a new unvented cylinder is that you will need sufficient mains pressure or flow rate to supply the appliance and also a safety discharge pipe. You will need to seek advise from a qualified plumber/heating engineer who is qualified to install and maintain unvented hot water systems over 15Litres.
