I have been requested to make a design for the owner of an 8 unit townhouse building.

the building is a single row house of older design but is currently gutted out for remodelling.

the building suffered a flood and therefore was required brought up to code.

previously the building was heated by baseboard hydronic hot water heating system and had no Air-COnditioning.

To get decent rents these days one must have Air-Conditioning so thats why he contacted me..

he wants to have installed a hybrid gas / electric HVAC system.. with heat pump and A/C.. and the ability to adjust temperatures per floor with variable capacity.

this would mean 17 indoor units.. (2 for each apartment and 1 for the Lobby area..)

currently there is a mini split handling the Lobby area and that will probably stay so I need 16 additional indoor units..

I need 1.5 Tons per indoor unit and they need to be ducted..

I first suggested a Daikin VRV system for cool and heat pump.. with a Hydronic kit for aux heat.

that was shot down as he wants each tenant to pay for their own electricity.. each unit is metered separate.. so that limits me to having an outdoor unit for each apartment...

The central boiler will have 17 Zones fitted to it and he plans to bill the apartments based on the number of minutes that a zone is calling for heat from the boiler in times of cold weather when heat pump is not operable..

so somehow I need to find a system with ducted ceiling mounted indoor units that can also handle a hydronic coil as well.. and be able to communicate with a central controller..

I was willing to design a custom control system, but he wants me to fit industry standard controls in case i am no where to be found in a few years..

my second thought was to fit a Mitsi city-multi system with a computer interface that could centrally shut down all the heat pumps at a certain outside temperature.. however I still need all the apartments to be able to adjust their temperatures by one controller and not have to worry about 2 thermostats.

those setpoints and room temps need to be reported to the central system as well the unit fans need cycled (or stay in per user request).. and of course the hydronic valves get cycled based on heat call..

what a wild system but I do not see how to do it without custom controls and software...

so I figured id ask if some of the members in europe where boiler heat is common have ever fitted a combination heat pump / Air-Cond / hydronic system such as this?

-Christopher