# Oil to Heat Pump Conversion in Seattle

> Oil to heat pump conversion in Seattle: air handler, panel, permits, tank decommissioning and Clean Heat rebates planned in the right order. See your next step.

URL: https://seattleheatpumpco.com/oil-to-heat-pump-conversion/

Updated: 2026-10-21

Oil to heat pump conversion replaces an oil furnace with an electric heat pump on your existing ducts, usually with an electric air handler where the furnace stood, and then retires the oil tank. [The Seattle Heat Pump Company](https://seattleheatpumpco.com/) plans oil conversions across Seattle and King County, sequencing the heat pump, the tank decommissioning and the rebates so nothing is lost along the way; licensed and insured contractors carry out the installation.

Oil heat is a shrinking but stubborn part of Seattle's housing. Census data from 2020 to 2024 shows about 2.9% of Seattle households, roughly 10,600, heating with fuel oil, and the city estimates 7,000 to 10,000 oil-heated homes remain, down from about 18,000 in 2018, with a goal of none by 2030. Several programs now help pay for the switch, and the order of the steps decides how much of that help you keep.

## What happens on the first visit

An oil conversion visit covers everything a gas conversion does, plus the tank and the chimney.

**The house and ducts.** A Manual J load calculation sets the size of the new system, because an oil furnace's output says little about what the house needs. A static pressure test shows whether the ducts can carry a heat pump's airflow. An oil furnace delivers very hot air, so its ducts, and especially its return, can be undersized for a heat pump that delivers warmer air at higher volume. Houses whose ducts started life on a gravity furnace get a closer look; the [older homes page](https://seattleheatpumpco.com/heat-pump-older-homes/) covers what changes there.

**The electrical service.** An oil furnace draws little electricity. A heat pump plus electric backup heat in the air handler draws a great deal more, so the panel size and existing loads decide whether a new circuit is enough or the service needs an upgrade. The [panel requirements guide](https://seattleheatpumpco.com/guide/heat-pump-electrical-panel-requirements/) explains how that is worked out.

**The tank.** Where it is matters: a basement tank, a buried tank in the yard, or one under a deck, driveway or side path. Fill and vent pipes on the outside wall are often the only visible sign of a buried tank. The visit notes access, any sign of leaking, and whether the city's records show an earlier tank on the property.

**The chimney and other appliances.** When the oil furnace leaves, its flue goes unused. If a gas or oil water heater shares that chimney, removing the furnace changes how the remaining appliance vents, and the venting has to be evaluated before the job closes. Older oil furnaces and duct wrap can also contain asbestos. The Puget Sound Clean Air Agency requires an asbestos survey before renovation, and an owner-occupant of a single-family house may do their own.

## Air handler or coil: why most oil conversions go all-electric

A heat pump's indoor coil can sit on top of a furnace, which is how [dual fuel systems](https://seattleheatpumpco.com/dual-fuel-heat-pump/) work with gas. With oil, that path rarely makes sense. Keeping oil backup means keeping the tank, the deliveries and the leak liability, and Seattle Clean Heat pays to move off oil, which requires the tank to be decommissioned.

So most oil conversions replace the furnace with an electric air handler, a cabinet that holds the indoor coil, the blower and electric backup heat strips. It usually goes where the oil furnace stood, which keeps the duct connections short. The backup strips are sized to the load and controlled tightly: Seattle's energy code keeps supplemental heat off above 40°F and requires the lockout set to 35°F or lower at final inspection. A heat pump sized to the house carries it through nearly every hour of a Seattle winter, where the design temperature is 24°F and Sea-Tac averages about one night a year at 20°F or colder, so the strips should run rarely. The [backup heat settings guide](https://seattleheatpumpco.com/guide/heat-pump-backup-heat-settings/) explains how to tell if they are running too much.

The [air handler replacement](https://seattleheatpumpco.com/air-handler-replacement/) page covers placement, coil matching and the cabinet options in more detail.

## The order of operations

Most of the money lost in oil conversions is lost to sequencing. The steps below are the order that protects your eligibility and keeps the house heated.

1. **Check PLIA before anyone touches the tank.** The Pollution Liability Insurance Agency's Heating Oil Loan and Grant Program offers up to $75,000 per project and is not income-limited, but PLIA must approve the work before it starts and does not reimburse work already done. Decommissioning first forfeits that money. PLIA takes applications in a limited window each year, usually in late fall, so check PLIA's site for the current dates.
2. **Confirm your rebate path.** Clean Heat's $2,000 rebate needs a qualifying Mitsubishi Electric heat pump and a participating contractor, and the $4,000 moderate-income bonus needs income verification. Income-eligible households should check HomeWise before getting quotes, since it covers the whole conversion.
3. **Measure and design.** Load calculation, duct test, panel review and tank assessment, then a scope. The [cost estimator](https://seattleheatpumpco.com/tools/heat-pump-cost-estimator/) gives a rough range before this step.
4. **Pull permits.** Refrigeration, electrical and mechanical permits for the heat pump; the decommissioner obtains Seattle Fire Department permit 6103 for the tank.
5. **Install and commission the heat pump** while the oil furnace still works, so the house is never without heat.
6. **Remove the oil furnace and decommission the tank.** An ICC-certified decommissioner pumps out the remaining oil and either removes the tank or fills it in place, then files the report with the fire department.

The [oil tank decommissioning](https://seattleheatpumpco.com/oil-tank-decommissioning/) page covers the tank side in full, and the [PLIA grant window post](https://seattleheatpumpco.com/blog/plia-heating-oil-grant-window/) tracks the current application cycle.

## What a conversion costs, and what comes off

There is no single published price for an oil conversion, and it is better budgeted as two parts. The heat pump side follows the ducted installation range: about $6,700 to $20,000 for Seattle-area projects on usable ducts. The tank side adds about $700 to $3,000 to fill a tank in place on a clean site, plus the $184 Seattle Fire Department permit per tank. These are budgeting ranges, not quotes.

Tank removal costs more than filling in place and depends on depth, size, access and restoration, so it is priced from the site rather than from a published range. A leak changes everything: the City of Seattle says cleanup can exceed $10,000, and PLIA says most completed cleanups exceed $60,000.

Other drivers sit on top of the base:

- a panel upgrade from 100 to 200 amps, typically about $1,333 to $4,500 in the Seattle area
- duct work where the return or trunks are too small
- the air handler's location and the line-set route to the outdoor unit
- chimney or venting work for an appliance left on the old flue
- asbestos abatement if the survey finds it

Incentives take a large bite. Seattle Clean Heat gives $2,000 off for oil-heated Seattle homes on qualifying equipment, plus $4,000 more for households at 81% to 150% of area median income, for installs completed within the program's current funding period. The Seattle Office of Housing's HomeWise program offers free conversions to income-eligible households. City Light's contractor discount of $300 or $600 is a separate program, so ask whether it can appear on the same invoice. The federal 25C credit ended for equipment placed in service after December 31, 2025. The [oil conversion cost guide](https://seattleheatpumpco.com/guide/oil-to-heat-pump-conversion-cost/) works through the numbers, and [a typical oil conversion](https://seattleheatpumpco.com/blog/typical-oil-to-heat-pump-conversion/) shows how the pieces fit on one house.

## Running costs: what can and can't be said

Washington has no official heating oil price series, so any precise oil-versus-heat-pump savings claim rests on numbers no public source backs. What is clear: City Light's current Seattle residential rate is 13.38 cents per kWh, a heat pump delivers several units of heat per unit of electricity through most of a Seattle winter, and the tank stops being a liability you carry. The [heat pump versus oil furnace guide](https://seattleheatpumpco.com/guide/heat-pump-vs-oil-furnace/) compares the two on cost, comfort and risk.

## Oil conversions outside Seattle

Clean Heat and HomeWise are City of Seattle programs, so they stop at the city line. That matters because some suburbs have higher oil shares than Seattle: Census data shows about 9.0% of [Burien](https://seattleheatpumpco.com/service-areas/burien/) households, 6.5% in Lake Forest Park and 4.1% in Shoreline heating with oil; the [Shoreline and Lake Forest Park page](https://seattleheatpumpco.com/service-areas/shoreline-lake-forest-park/) covers that area's details. Those cities are on City Light electricity at the suburban rate of about 14.64 cents per kWh, so the operating math still favors a heat pump, but the rebate stack is thinner. PLIA's program applies statewide. Tank permits in Shoreline and Lake Forest Park go through Shoreline Fire, and Bellevue issues its own. On the Eastside, PSE's published heat pump rebates cover electric resistance and gas heat rather than oil. The [Seattle permit guide](https://seattleheatpumpco.com/guide/seattle-heat-pump-permit/) covers the heat pump permits inside the city.

## What's included

- Load calculation and duct assessment for the house
- Electrical service review for the heat pump and backup heat
- Electric air handler in place of the oil furnace, with a matched outdoor unit
- Backup heat sized and locked out per Seattle's energy code
- Removal of the oil furnace and its oil supply line
- Review of the chimney and any appliance that shares it
- Coordination of tank decommissioning by an ICC-certified decommissioner
- Rebate paperwork sequenced so eligibility is not lost
- Permits, inspections and startup commissioning

## How an oil conversion usually takes shape

|  | Air handler on existing ducts | Air handler plus duct work | Heat pump with a panel upgrade |
| --- | --- | --- | --- |
| What changes | Oil furnace out, electric air handler and outdoor unit in, tank decommissioned | The same, plus added returns, sealing or replaced runs | The same, plus a larger electrical service |
| Typical situation | Ducts test as usable and the panel has room | Ducts sized for a hot oil furnace, too small on the return side | Small or full panel and electric backup heat in the design |
| What the assessment checks | Air handler location, backup heat size, tank location | Static pressure, return area, leakage | Service size, existing loads, backup heat draw |

## Questions

### Is Seattle's Clean Heat rebate only for low-income households?

No. The $2,000 Clean Heat rebate is open to oil-heated Seattle homes regardless of income, on a qualifying Mitsubishi Electric heat pump through a participating contractor. Households at 81% to 150% of area median income can add $4,000 for installs completed within the program's current funding period, and income-eligible households can get a free conversion through HomeWise.

### Do I have to decommission the oil tank when I convert?

Yes, in practice. Seattle's fire code requires a tank out of service for a year or more to be decommissioned, and Clean Heat requires the tank to be decommissioned under Seattle Fire Department rules. The work is done by an ICC-certified decommissioner under a $184 permit, either by removing the tank or filling it in place.

### What happens to the oil left in my tank?

Leftover oil and sludge are pumped out as part of decommissioning and handled by the decommissioner or a used-oil recycler. Running the tank low before the switch reduces how much is left, but keep enough to heat the house until the heat pump is running and commissioned.

### Can I keep the oil furnace as a backup?

Technically a heat pump coil can sit on an oil furnace, but it defeats the purpose of most conversions. Clean Heat pays to move off oil, which requires the tank to be decommissioned, and keeping oil means keeping the tank and its liability. Most conversions use an electric air handler with backup heat strips instead.

### Can I still get a federal tax credit for a heat pump?

No. The federal 25C credit ended for equipment placed in service after December 31, 2025, so a conversion today does not qualify. The federal IRA home energy rebates had not launched in Washington. Local programs such as Clean Heat, HomeWise and City Light's contractor discount are where the savings are now.