Hot water heat recovery

What device(s) to put where to recapture as much of the heat from waste / grey water needs a decision.

The solutions from www.recoupenergysolutions.co.uk are clearly all very efficient and appear to be the same or similar to those that are well used in the US, where a lot of properties have their heating systems in the basement.

They are based on an “instant” transfer of the waste water heat to the mixer in the shower and also to the cold water feed to the water heating system.

BUT, the planned house will have clothes washing machines, a dishwasher and 2 showers on the ground floor. Being on the ground floor they wouldn’t work with all the recoupenergy solutions. Also a washing machine, dishwasher, bath (or hot tub) generates the waste water, some time after the hot water tank has been re-filled with mains cold water.

So in those circumstances, the www.esavep.com/products/hot-water-cylinders Heat Squirrel (scroll to the bottom) could be better and could provide a single (so a lot cheaper) whole house solution for all waste / grey hot water heat recovery. They are about £399 (not installed). The heat squirrel has a 120 litre capacity.

A key consideration / idea will be:

Can the waste water input be regulated so that only waste water that is warmer than the water in the heat squirrel is let in to it?

It seems that for a shower, the recoupenergy solutions will be the most efficient, but for the whole house, and the total cost, a single heat squirrel could be better than a heat squirrel and one or more recoupenergy solutions.

Heat Squirrel Schematic

Heat Squirrel - schematic
Heat Squirrel - installed