A climate that works both halves of the system
Reno asks a lot of a heating and cooling system. The high desert brings large swings from afternoon to night and from summer to winter, so many homes need real heating capacity for cold nights and real cooling capacity for hot afternoons, sometimes in the same week in spring and fall. A system sized only for one season tends to struggle in the other.
Sizing for Reno's winters
Washoe County's residential design criteria use a 17°F winter design temperature, and a contractor's load calculation for a Reno home should use the local figure rather than a generic one. That matters most if you are considering a heat pump. Many modern heat pumps keep working well below freezing, but their capacity drops as it gets colder. Ask any contractor quoting a heat pump to show the unit's rated capacity near Reno's design temperature, and what provides backup heat on the coldest nights, whether that is electric resistance strips or a gas furnace in a dual-fuel setup.
Gas furnaces remain common in Reno. On older furnaces, have the heat exchanger, venting and flue checked each fall, along with a carbon monoxide test. Furnaces in garages and attics are exposed to the cold themselves, so condensate lines on high-efficiency furnaces should be protected from freezing.
Dry air and cooling
Reno's dry air helps air conditioners: with little humidity to remove, a correctly sized system cools efficiently. Evaporative coolers are also used in parts of northern Nevada because they rely on dry air to work. If you have one, it needs seasonal service and winterizing to keep its water lines and pads from freezing and scaling. If you are adding central air to a home that has only had a swamp cooler, the ducts may be undersized for refrigerated air, so ask the contractor to check them.
Nevada falls in the Department of Energy's Southwest region, so any new central air conditioner must meet that region's efficiency minimums.
Snow, roofs and outdoor units
Snow loads in Washoe County vary by site and elevation. Outdoor heat pump units should sit on a stand high enough to stay above typical snow and to let defrost water drain away, and rooftop or wall-mounted equipment should be checked after heavy storms. Clear snow away from the outdoor unit and from high-efficiency furnace intake and exhaust pipes after a storm, because blocked vents can shut a furnace down.