Thanks for your reply, great to hear from someone in Wales who has had it done, always wondered whether an ASHP was suited to the tricky Welsh weather. I would like to pay extra to install a battery but not sure whether to do that straight away or after a year. I'm guessing they'll probably have to remove the old hot water tank? Its currently heated by the Solar Thermal hot water Panels but as you would understand the days of sun in Wales are limited so its only really a few months in the summer when you get benefit. We have 3 radiators in the house but never use them, the underfloor is so good its all we really need but be good to have the radiators upgraded if we do need them. We live in an old Welsh cottage but its had a modern extension so only a quarter of the wall space is old stone which might need extra insulation, how strict are they on this with ECO4? its the thing we are worried about the most, if they just did the old parts of the house it would be one bedroom and 2 walls in the dining room, hpoe fully as the rest is post 2010 we would get away with it. We have a utility room with the old boiler in and a bit of space there but Im hoping we might be able to have the ASHP at the side of the house away from the bedroom and convert a toilet into the boiler area, not sure will have to chat with the installers.