HVAC in Montana is a no-heat problem with more than one machine behind it. Boilers in older towns, furnaces in basements, propane on rural places, and heat pumps in milder western valleys that still hit a hard snap are not interchangeable. Chinook swings make condensate lines freeze after a thaw and make a system short-cycle when the night returns. Say the town and what the equipment did on the last swing. A burner that will not light is not the same as rooms that never catch up.
Combustion air, the flue, and the heat exchanger come before any talk of comfort. If you smell trouble, stop running the unit. Intake pipes on high-efficiency equipment ice or drift over, especially where wind stacks snow on one wall. Filters in a dusty plains house and filters in a smoky valley season are different kinds of plugged. Ask what was ruled out. Ducts in a cold crawl under a mountain house lose the heat before it reaches the room that needs it.
Elevation and a wide daily swing mean a brochure size is a guess. Ask whether the load was figured for this house, this glass, and this wind, or copied from the old label. Matched equipment matters if cooling is part of the change. Many valleys need cooling for a real stretch of hot afternoons even though the nights fall hard. Efficiency labels compare a test. They are not a promise about your fuel. Wood stoves and shop heaters are not a substitute for saying the main system is down.
Replacement is saner in a shoulder season, and a dead system does not offer that choice. Say if the house is cold now. Garages, additions, and rooms over unheated space are the rooms that expose a lazy duct design. A thermostat in a sunny south room will lie about the north bedrooms after a chinook glare fades. Mention that if it is your pattern.
Say heat or cooling, the town, and whether the unit is dead or only losing. Mention ice on a termination or a swing that froze the drain. If the house is cold, say so. Montana nights do not negotiate with a waiting list. Call the number on this page.