I want to convert a 5 family building from oil fueled steam heat to a more sustainable system. What do you suggest?

Dona,

I have found good results converting to mini-split air-source heat-pumps when moving from central boiler systems with through wall or window air conditioning.

I recommend Mitsubishi's Citi-Multi system.

• It has a central roof top mounted condensing unit, with individual indoor units that would be installed in the bedrooms and living areas.
• You can manage the indoor units from a single networked PC.
• And it enables you to bill the calculated HVAC electricity consumption per tenant. If tenant #1 wants it hot and tenant #2 wants it cooler, this system can handle each request on a room-by-room basis.

6-16 ton units meet ENERGY STAR Commercial Requirements and will exceed the 2010 ASHRAE 90.1 efficiency ratings. This system can provide 100% heating capacity at 0˚ F and 84% heating capacity at -13˚ F.

In the summer there will be condensation produced at each indoor unit. I recommend finding a route, if not inside a wall, then through a small chase (fire-stopping at each floor/ceiling penetration) in a closet or corner, so the water can gravity feed down to a floor drain or utility sink in the basement.

I also recommend that other energy saving improvements like adding attic insulation be completed before any new system is designed, so it can be right-size d to your new thermal envelop.

Good luck with your project,

Edward

For more information:

Read Randy Potter's Q&A "I can't afford geothermal. Is an air-to-air heat pump my best option for heating?"

Also, check Richard Parker's Q&A "Can you help me select a high efficiency furnace?"