Works proceeds apace. The heat-pump is being installed - no surprises so far.   Question. The internal unit of the heat-pump (DHW included) will sit in the following space. Formerly a small garage, it will now be a bike shed/storage space/technical room; we'll replace the outside metal door by a wooden door. Should we also put a small radiator in that space?     I imagine the heat-pump's internal unit and the water heater: - have a certain minimal ambient temp