# What a typical oil-to-heat-pump conversion looks like, start to finish (illustrative) > An illustrative walkthrough of a typical Seattle oil-to-heat-pump conversion: tank records, rebates, sizing, permits, install and tank work. Plan yours. URL: https://seattleheatpumpco.com/blog/typical-oil-to-heat-pump-conversion/ Updated: 2026-10-21 *A composite, illustrative example of how a Seattle oil conversion usually unfolds, step by step. It is not a real customer's project, and it shows no real results.* > **Note:** This is an illustrative walkthrough, not a real project. The house, the decisions and the sequence are a composite of how a typical Seattle oil-to-heat-pump conversion runs under the rules and programs in place. No real customer, outcome or savings figure is described. A typical oil-to-heat-pump conversion in Seattle replaces an oil furnace with a ducted heat pump on the existing ducts, then decommissions the oil tank under a fire department permit. Done in the right order, it also captures the rebates the house qualifies for. [The Seattle Heat Pump Company](https://seattleheatpumpco.com/) plans and manages these projects, with the work carried out by licensed and insured contractors, and this walkthrough follows one illustrative house from the first call to the tank report. ## The example house Picture a 1950s single-story house in north Seattle with a daylight basement. An oil furnace sits in the basement, connected to ducts that reach every room through floor registers, with one central return in the hallway. A buried oil tank sits in the side yard, its fill pipe poking up near the foundation. The furnace still runs, but it is old, and the owners want cooling for summer too. That profile is common for a reason. Census estimates put about 10,600 Seattle households on oil heat, and the city estimates roughly 7,000 to 10,000 oil-heated homes remain. ## Step 1: The first call and the tank record The first conversation covers what heats the house, which rooms run cold or hot, the electric service size, and whether the owners know anything about the tank. Before the visit, the tank gets looked up in the Seattle Fire Department's residential decommissioning records, which go back to 1996. In our example, no record turns up, which means the tank has never been decommissioned under a permit, or was handled before 1996. The fill pipe says the former. ## Step 2: Deciding the money before anyone touches the tank This step comes early because the order matters: - **Seattle Clean Heat** takes $2,000 off a qualifying Mitsubishi Electric heat pump installed by a participating contractor in an oil-heated Seattle home. Households at 81% to 150% of area median income can add $4,000 for installations completed within the program's current funding period. Income-eligible households below that range can get a no-cost conversion through the Office of Housing's HomeWise program. - **City Light's contractor discount** adds $300 or $600 depending on the equipment tier. - **PLIA's Heating Oil Loan and Grant program** can fund up to $75,000 per project, with no income limit, but PLIA must approve the project before any tank work starts. In this example, the owners have no sign of a leak and plan to fill the tank in place, so they decide not to wait for a PLIA application window. Owners who suspect a leak, or want PLIA's loan for the conversion, would apply first. The [PLIA grant window post](https://seattleheatpumpco.com/blog/plia-heating-oil-grant-window/) explains that decision, and the [rebate guide](https://seattleheatpumpco.com/guide/heat-pump-rebates-seattle/) keeps the current amounts. ## Step 3: The assessment The assessment is a measurement visit: - **Load calculation.** Room by room under ACCA Manual J for Seattle's 24°F design day. The house has had attic insulation and newer windows since the furnace went in, so the heat pump it needs is smaller than the furnace's rating would suggest. The [Manual J sizing guide](https://seattleheatpumpco.com/guide/heat-pump-sizing-manual-j/) explains why. - **Ducts.** A static pressure reading with the blower running. The single return is small for the airflow a heat pump needs, so the plan adds a second return. Everything else measures fine. [Using a heat pump with existing ductwork](https://seattleheatpumpco.com/heat-pump-existing-ductwork/) covers what the readings mean. - **Electrical panel.** The panel has room for the heat pump circuit but not for large backup heat strips, so the design uses a modest strip size that fits. A house with less panel room would need a service upgrade. - **Outdoor unit location.** The rear yard keeps the unit well under Seattle's 45 dBA nighttime limit at the property line, avoiding a side-yard noise review. - **Asbestos.** Puget Sound Clean Air Agency requires an asbestos survey before renovation. The owners, as owner-occupants, may survey themselves; they hire an inspector to test the old duct wrap near the furnace instead. ## Step 4: The quote The quote lists equipment model numbers, the added return, the air handler, the line set, the electrical work, permits and the tank decommissioning as separate lines. Using Seattle-area budgeting ranges a ducted heat pump on usable ducts typically runs about $6,700 to $20,000, filling a clean tank in place about $700 to $3,000 plus the $184 fire permit, and Seattle permits for a typical job about $192 to $556. These are ranges, not quotes, and this walkthrough assigns no price to its example house. The [oil conversion cost guide](https://seattleheatpumpco.com/guide/oil-to-heat-pump-conversion-cost/) shows how the pieces combine. ## Step 5: Permits Inside Seattle, a licensed refrigeration contractor obtains the refrigeration permit for the split system. An electrical permit covers the new circuit, and a mechanical permit covers the furnace replacement. The tank permit is separate: the Seattle Fire Department issues it to the ICC-certified decommissioner, and no work starts until the application is stamped approved to proceed. The [Seattle permit guide](https://seattleheatpumpco.com/guide/seattle-heat-pump-permit/) lists each one. ## Step 6: Installation The oil burner and furnace come out. An electric air handler goes in where the furnace stood, connected to the existing supply plenum and the new return. The outdoor unit sits on a pad in the rear yard, and a line set runs through the basement wall. The line set is pressure tested with nitrogen, pulled into a deep vacuum, then charged. Inspectors check the work at cover and final. ## Step 7: Commissioning Commissioning verifies airflow at the air handler, refrigerant charge, defrost operation and the backup heat controls, which Seattle's energy code requires to keep electric strips off above 40°F outdoors. The owners get a walkthrough of the thermostat and filter. ## Step 8: The tank With the heat pump running, the oil system is shut down for good. The certified decommissioner pumps out residual oil and sludge, cleans the tank, fills it with an inert material and caps the fill and vent pipes. Seattle doesn't require soil sampling for either removal or fill in place, though owners can request it. The decommissioner files a report with the fire department within 30 days, and the owners keep the permit, report and receipts for any future sale. The [oil tank decommissioning](https://seattleheatpumpco.com/oil-tank-decommissioning/) page compares removal with filling in place, and the [oil to heat pump conversion](https://seattleheatpumpco.com/oil-to-heat-pump-conversion/) page covers the full service.