Furnace Installation in San Rafael

Sizing a furnace for this house starts with understanding what the burner and ignition system are actually asked to carry. Homes in Marin County, CA run heat about nine months a year, from October through June. A contractor doing a load calculation here cannot treat duct layout or equipment capacity as secondary details, because a system that cycles through that many heating months exposes every weak point in the install. Heat exchangers and igniters that might hold up through a brief season will degrade faster when they spend the better part of the year working. A contractor who skips a proper Manual J and installs by rule of thumb leaves the homeowner with a furnace that either short-cycles or runs long, and either failure mode compounds across a season this length.

Ductwork laid in for an earlier generation of equipment is what a furnace installer encounters in a large share of Marin County homes. Half the homes in Marin County, California were built in 1967 or earlier (2020-2024 ACS 5-year). That matters because the ducts, not the new unit, are where an installation either works or stalls: sheet metal sized for a smaller system may not move enough air, and a contractor has to measure what is actually there before any equipment decision holds. The electrical side follows the same logic. What is already in the house sets the real scope, and the furnace itself is priced after that picture is clear.