Gas/Wet Under Floor Heating (UFH) - expensive to run ?

Pincher

Usually you get a central boiler to avoid supplying gas to the apartments, in order to sidestep a lot of safety requirements, not to mention the ducting nightmare of getting rid of the plumes.

If there is gas water heater for each apartment, they might as well put in a combi which supplies the UFH within the apartment as well. It localises the plumbing, the resident pays his own gas bill. It saves a lot on maintenance and admin on the distribution, metering and collection of heating bills.

In fact, I wouldn't be surprised if the leaseholders cut off the central supply, and put in a combi themselves.