Cost of furnace replacement in Hawaii (HI)
A 40,000 BTU furnace installed
$3,400to $5,000
That is a standard 80% AFUE model, the federal minimum and what most replacements are. A 96% condensing furnace runs $4,400 to $6,600.
Is the efficient one worth it here?
Costs more
$1,300
Saves a year
$0
Pays back in
Never
Hawaii's heating season is short enough that the efficiency has little to work with — 0 heating degree days at $6.34 a therm. The cheaper furnace is usually the better buy here, and the difference is worth putting into insulation instead.
Before you replace like for like
A furnace is not the only option. A heat pump does the same job using electricity, and in some states costs less to run — it depends on the gap between gas and electricity prices where you live, which is not the same everywhere.
Compare both in HawaiiCommon questions
How much does it cost to replace a furnace in Hawaii?
Between about $3,400 and $5,000 installed for a standard 80% AFUE furnace, or $4,400 to $6,600 for a 96% condensing model. A 1,800 square foot home in Hawaii needs roughly 40,000 BTU of output.
Is a high-efficiency furnace worth it in Hawaii?
No. It does not repay its extra cost here.
What size furnace do I need?
About 40,000 BTU for 1,800 square feet in Hawaii's climate — roughly 22 BTU per square foot, which reflects 0 heating degree days a year. Colder states need more output for the same house.
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Sizing from Hawaii's heating degree days for a 1,800 square foot home. Gas price from the US Energy Information Administration, 2026-07. Installed costs are a national estimate spread ±20% — ductwork, venting runs and your region move real quotes more than the furnace itself does. Get three.