I have 3 properties all with heat / recovery / ventilation systems.
One important point to note is the noise levels from the recovery unit itself.
I have used a company from the North for the last 2 systems
They supply everything as a kit for self install, very simple job if you are anyway handy, around 1 day to run ducting easy job in a new build and €1500 to supply all the kit and drawings.
All you need is a plumber to connect a drain pipe to the unit, and electrician for power supply. PM for any further info
jj