Hi, I'm in the midst of renovating a ~5500 sq ft commercial building and converting it to a ~6000 sq ft multi-family residential. It'll have 6 resi rental units + 1 ground-level commercial space. The building currently has natural gas and uses radiator heating, there is no central cooling system. We currently have a small central boiler that provides hot water, but it's undersized once we add 8 showers, 7 dishwashers, 2 common W/D, 2 in-unit W/D, etc.

My question is what's the best strategy for adding heating/cooling to each unit? And what's the best way to improve the provision of hot water?

Our current plan is to install VTACs for heating/cooling, or vertical terminal air conditioners, in each unit (GE Zonline, see here http://www.geappliances.com/ge/zoneline.htm), sub-metered to each tenant's electric meter. Does anyone have experience with VTACs for residential rentals? Pros and cons? Is there a better way to do heating/cooling?

In terms of hot water, we were planning to install a Commercial High Efficiency Gas Water Heater in the basement (Rheem's SPIDERfire Water Heater, see here https://www.grainger.com/product/6FGU6), and use it to serve all 7 units. What do people think of this?

Thanks for your time & help

In my area the zoneline setup is used in basically all new apartment style condos (of which there are hundreds and hundreds). One in the living room, separate one for the master bedroom is the usual setup. They are effective and easy. If you’re doing anything studio style you could probably get away with 1 unit.

Not familiar with that specific hot water heater.

What about doing mini splits in the units?