I am in the process of getting my loft ready for (and doing some of the fitting of) a multi-phase process. An extension is being undertaken and the current heating and hot water system is being significantly changed.   Currently we have an vented heating and hot water system, with heat coming from a regular 'heat only' boiler in the ground floor kitchen. An expansion / feed tank in the  middle of the loft for this system, a pump in the airing cupboard on the first floor on the opposite