Cooling a Buffalo double

How doubles are usually set up

A typical Buffalo double has a lower flat and an upper flat with separate entrances, often with an attic above the upper. Heat is commonly one furnace or boiler per flat in the basement, sometimes one shared. Check which you have before asking for quotes, because it decides what can be added.

The common options

• Two central systems. If each flat has its own furnace and ducts, each gets its own coil and outdoor unit. Ducts to the upper flat usually run up through a chase or closet from the basement.
• Attic system for the upper, coil for the lower. The upper flat is the hottest. An air handler in the attic can cool it from above while the lower flat uses its furnace ducts.
• Ductless heads. In a radiator-heated double, one or two heads per flat on separate outdoor units, so each tenant controls and pays for their own. Ductless mini splits.

Where the outdoor units go

City lots are narrow. Two outdoor units in a side yard can end up close to the neighbor's windows. Ask the installer where each unit will sit, how far the line sets run, and how it will be kept above snow in winter. Some doubles put the upper flat's unit on a wall bracket or a flat roof.

If you rent out one flat

• Separate systems on separate electric meters keep the cooling cost with the tenant who uses it.
• A heat pump on one flat can qualify for NYS Clean Heat incentives through a participating contractor. National Grid says amounts vary with the job, and a two-unit building may be treated differently from a single-family home, so ask. Heat pumps.
• Get the contract in writing. New York's home improvement law covers installing air conditioning and requires a written contract for jobs over $500.