Air-source heat pump vs. Propane furnace
Heat pump vs. propane furnace: the foothills and north-county question
Where there is no gas main — Deming, Kendall, Custer, Point Roberts — the real choice is a heat pump against propane. Propane wins on outage-free cold snaps; the heat pump wins on the bill.
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The short answer
The heat pump wins on running cost almost every year, because propane is delivered fuel at delivered-fuel prices. Keep the propane furnace as the backup stage rather than the primary, especially above 500 feet. Go propane-only if the site cannot take an outdoor unit or your power is genuinely unreliable.
Air-source heat pump vs. Propane furnace, line by line
Where one option is genuinely better for a Bellingham house, the cell is marked. Where it is a wash, we say so.
| What you are comparing | Air-source heat pump | Propane furnace |
|---|---|---|
| Fuel cost | PSE electricity, metered, at a heat pump’s multiplier. Rates change but the multiplier does not. better | Delivered propane, priced by the tank fill and the haul. It is the most expensive common heating fuel in Whatcom County. |
| Heat output at 13°F to 19°F | Reduced, and a cold-climate unit is not optional up the Mount Baker Highway. | Full rated output regardless of the weather, which is why propane furnaces persist where the design temperature is 13°F. better |
| Cooling | Included. better | None. You are adding an air conditioner or living with the summer. |
| Fuel logistics | Nothing to schedule. No tank, no minimum fill, no driveway the truck cannot make in February. better | A tank on your property, a delivery route, a minimum fill and a supplier relationship. Real friction on a rural road. |
| PSE rebate | A propane-heated house does not qualify for PSE’s $1,500 rebate, which requires existing electric resistance heat. No conversion rebate applies. | No PSE rebate either; PSE does not incentivise propane equipment. |
| Outage performance | Nothing runs without power. | Nothing runs without power either, since the blower and controls are electric — but a propane furnace pairs easily with a small generator, and many rural Whatcom homes already have one. better |
| Existing ductwork reuse | A ducted heat pump reuses the same ducts, so the conversion is mostly outdoor equipment plus a coil or air handler. | Swapping furnace for furnace is the cheapest single move if the ducts are sound. better |
| Combustion safety | No combustion appliance, no flue, no CO. better | A vented combustion appliance that wants annual inspection, and a CO detector that is not optional. |
Rows with no mark are close enough that the difference will not decide your project.
Choose Air-source heat pump if
- You are staring at annual propane fills and want the heating bill to be a metered number instead of a delivery invoice.
- You have ducts already and want cooling as well, which makes the heat pump close to a two-for-one.
- You are building or re-siding and can get the electrical and refrigerant runs in cheaply while the walls are open.
- The property is in the north-county farmland — Custer, Everson, Nooksack — where the design temperature is closer to Bellingham’s 19°F than to Glacier’s 13°F and a heat pump carries almost the whole season.
Choose Propane furnace if
- The furnace is young and working, and the propane tank is already on site and paid for. There is no local rebate to subsidise the switch.
- You are up the Mount Baker Highway where 13°F design temperatures and long outages are normal, and you already run a generator that a furnace blower can live on.
- The site cannot host an outdoor unit within reach of snow-clear ground, or you have no legal, level spot with clearance.
- You want the propane furnace retained as the second stage of a dual-fuel system, which is often the best engineering answer in the foothills even though PSE’s all-electric rebate programs do not permit dual-fuel.
What changes this answer in Bellingham
Propane is not a legacy oddity in Whatcom County, it is the consequence of geography: there is no gas main in the foothills or in much of the farmland, so those areas run on propane, oil and wood. Point Roberts is the extreme case, a US exclave reachable only through Canada or by boat, which shapes both fuel delivery and service scheduling. The rebate picture is bleak and worth stating outright. PSE’s $1,500 conversion rebate requires existing electric-resistance heat, so propane-heated homes get nothing from it, and PSE’s gas-side conversion rebates require PSE natural gas service, which no Whatcom address has. What remains is the PSE midstream equipment discount of $300 to $600 by SEER2 and HSPF2 tier, PSE weatherization instant rebates, and income-qualified help through the Community Energy Challenge or Washington HEAR administrators. Size the equipment against the right design temperature for your elevation, not against Bellingham’s.
Washington's energy code puts Bellingham's outdoor heating design temperature at 19°F, against 24°F at Sea-Tac, in climate zone 4C (marine). We size from a load calculation against that number, not from the square footage of the house.
Money that moves this decision
-
Midstream HVAC Equipment Discount
Puget Sound Energy (with ICF)
$300–$600
Available nowTier 1 $300 (SEER2 ≥15.2 / HSPF2 ≥8.1, retrofit only) · Tier 2 $400 (SEER2 ≥15.2 / HSPF2 ≥8.5) · Tier 3 $600 (SEER2 ≥16 / HSPF2 ≥9.5).
Bellingham note: Whether this discount can be combined with the $1,500 conversion rebate is unconfirmed: PSE’s conversion page says its rebate "cannot be combined with any other rebates except where noted", while PSE’s heating hub tells customers to ask their contractor. We quote it separately and confirm with a PSE Energy Advisor before counting it toward your total.
- Paperwork:
- Comes off the equipment price
- Deadline:
- No published end date
- Verified:
- 2026-09-04 · source
-
Weatherization Instant Rebates
Puget Sound Energy
$0.20–$2.50 per sq ft
Available nowAttic R11-or-less → R49 $1.75/sq ft up to $3,500 · wall R0 → R13 $2.50/sq ft up to $5,000 · floor → R30 $2.50/sq ft up to $5,000 · air sealing $0.20/sq ft up to $400 each for attic and floor · duct sealing up to $1,000.
- Paperwork:
- We file it
- Deadline:
- No published end date
- Verified:
- 2026-09-04 · source
-
Washington State HEAR — Home Electrification and Appliance Rebates
WA Dept. of Commerce via local administrators
Varies by administrator
Income-qualifiedCommerce awarded $39.3M across 40 local administrators with no statewide schedule. Whatcom-relevant awards: Sustainable Connections $731,250, Opportunity Council $500,000, Lummi Nation $950,500. Per-household amounts are not published.
- Paperwork:
- The program files it
- Deadline:
- While administrator funds last
- Verified:
- 2026-09-04 · source
-
Community Energy Challenge — moderate income
Sustainable Connections + Opportunity Council
Up to $2,000
Income-qualifiedFor a ductless heat pump upgrade. Weatherization incentives average roughly 45% of project cost. Stated by CEC to be in addition to utility rebates.
- Paperwork:
- The program files it
- Deadline:
- Ongoing
- Verified:
- 2026-09-04 · source
-
Low-Income Weatherization
Opportunity Council (Whatcom, Island, San Juan)
No cost to qualifying households
Income-qualified- Paperwork:
- You file it
- Deadline:
- Ongoing
- Verified:
- 2026-09-04 · source
Questions Bellingham homeowners actually ask
- Will PSE pay me to switch from propane to a heat pump?
- No. PSE’s $1,500 conversion rebate requires your existing primary heat to be electric resistance, and its gas-conversion rebates require PSE natural gas service that does not exist in Whatcom County. A propane-to-heat-pump project can still pick up the PSE midstream equipment discount of $300 to $600 and weatherization instant rebates, and income-qualified households should talk to Sustainable Connections or the Opportunity Council.
- Is a dual-fuel propane and heat pump system a good idea here?
- In the foothills, frequently yes. The heat pump handles the 35°F to 55°F hours that make up most of the season and the propane furnace takes the deep cold, which is where propane’s constant output earns its price. The trade-off is that PSE’s all-electric heat pump rebates do not permit dual-fuel systems, so you are buying comfort and fuel savings rather than an incentive.
- Can I keep my propane tank for the water heater and range?
- Yes, and many households do. Converting space heating to a heat pump does not require abandoning propane for cooking or hot water, though it will shrink your annual usage enough that you should re-check your supplier’s minimum-fill terms before you commit.
- How cold is too cold for the heat pump at my elevation?
- Use the code number for your area rather than a guess. WAC 51-11C-80100 lists Bellingham at 19°F, Blaine at 17°F and Glacier at 13°F, and those differences change equipment selection. A cold-climate unit with published capacity at low ambient, plus a backup stage sized for the design day, is the configuration that holds up.
- Do you service propane furnaces?
- We service and repair furnaces, and we install heat pumps and ductless systems. Any gas-piping or propane-piping work that requires a plumbing or gas-fitting licence we do not hold goes to a licensed contractor, and we will say so before the visit rather than after.
Next steps on this decision
Get this priced both ways
We will quote the option that fits your house and tell you what the other one would have cost, so the comparison is yours to make, not ours.
Ready for a straight answer on your house?
Tell us what you have now and what you want it to do. We will tell you what fits, what it costs, and which rebates you actually qualify for — before anyone comes out.
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