The heat pump looks like a big fridge – i.e.  Approximately 1.8 meter high and 800mm square. 

It never gets installedin the roof like a geyser but on ground level. The heat pump cannot rest on the roof rafters

because the weight of the het pump when full of water, will weigh at least 450 Kg to 500 Kg and is too heavy to rest on the rafters.

The heat pump also cannot lie on its side because of the refrigeration in the top of the unit.