# What a gas-to-heat-pump conversion day looks like: an illustrative walkthrough > An illustrative walkthrough of a Sacramento gas furnace to heat pump conversion, from the first visit and permit to install day, ECC-Rater testing and handoff. URL: https://tulesacramentoheatpump.com/blog/gas-to-heat-pump-conversion-day/ Illustrative Walkthrough An illustrative walkthrough, not a real job: how a typical Sacramento conversion from a gas furnace and central AC to a ducted heat pump runs, from the first visit to the final inspection. > An illustrative walkthrough > > This post describes what a typical job looks like from start to finish. It is not the record of a specific completed project. > An illustrative walkthrough > > This post describes a typical conversion in general terms. It is not a record of a real job, a real house or a real customer, and timings vary with the house, the ducts and the panel. Picture a single-story Sacramento-area house with a gas furnace in the garage, a central air conditioner on a pad by the side fence and ducts in the attic. Both pieces of equipment are old enough that the owners want to replace them together, and they want one electric system instead of two. This walkthrough follows that kind of project from the first visit to the day the inspector signs off. ## Who plans and does the work [Tule Sacramento Heat Pump](https://tulesacramentoheatpump.com/) plans and installs gas furnace to heat pump conversions across the Sacramento region, with the work carried out by licensed and insured contractors (C-20 for HVAC, and C-10 for any panel work). The steps below follow how those contractors run a conversion; the [gas furnace to heat pump conversion](https://tulesacramentoheatpump.com/gas-furnace-to-heat-pump-conversion/) page covers the service itself. Key takeaways - The first visit decides the job: equipment ages, a Manual J load calculation, a duct and static-pressure check, the panel, the outdoor location and the utility - The permit is pulled before install day - Install day runs in a fixed order: refrigerant recovery, set, braze, pressure test, evacuation, charge and airflow check - An ECC-Rater verifies ducts, charge and airflow after the installation - The thermostat walkthrough at handoff matters as much as the equipment ## Before the day: the first visit ### What gets measured The first visit is where most of the decisions are made, so it takes longer than a quick look at the old equipment. In this kind of house it covers: - **System ages and model plates** for the furnace, the coil on top of it and the outdoor condenser. - **A Manual J load calculation** for the house (the [sizing guide](https://tulesacramentoheatpump.com/guide/heat-pump-sizing/) explains why), because the old furnace and the old air conditioner were rarely sized to the same load. - **A duct and static-pressure check** to see whether the existing ducts can carry the airflow a heat pump needs. Title 24 sets a minimum of 300 cfm per ton for the refrigerant charge check, and [heat pump ductwork](https://tulesacramentoheatpump.com/heat-pump-ductwork/) covers what happens when the ducts fall short. - **The electrical panel,** its size and its open spaces, since the heat pump circuit and any backup heat strips need room. - **The outdoor location,** whether the new unit can sit where the condenser did, with clearance and drainage. - **The utility.** SMUD, Roseville Electric or PG&E changes both the running cost and which rebate applies. ### What the quote then shows From those findings the quote names the equipment, the capacity, any duct sealing or replacement, any electrical work and how backup heat will be handled. If the owners are SMUD customers and want the heat pump rebate, the quote also says that qualifying equipment will be installed by a participating contractor in the SMUD Contractor Network. The [quote comparison guide](https://tulesacramentoheatpump.com/guide/how-to-compare-heat-pump-quotes/) lists what a complete quote should spell out, and the [conversion cost guide](https://tulesacramentoheatpump.com/guide/gas-furnace-to-heat-pump-conversion-cost/) explains the price ranges. ## The permit comes first Every installed heat pump in California needs a building permit. Inside the City of Sacramento a one- or two-family change-out goes through the online minor permit, and the standard web permit assumes the new unit goes in the same spot and is no more than 25% larger than the old one. In unincorporated Sacramento County, which includes Carmichael, Fair Oaks and Arden-Arcade, a residential heating and cooling permit is applied for online and issued once paid. A panel upgrade needs its own electrical permit. The [permit and Title 24 guide](https://tulesacramentoheatpump.com/guide/heat-pump-permit-title-24/) covers each office. ## Install day, in order ### Morning: the old system comes out 1. **Refrigerant recovery.** The refrigerant in the old air conditioner is recovered into a cylinder, not vented. 2. **Gas shutoff.** The gas branch to the furnace is shut off and capped, and the old flue opening is closed off so it cannot leak air or let water in. 3. **Removal.** The furnace, its coil and the old condenser come out, and the electrical supply to the old equipment is made safe. ### Midday: the new system goes in 1. **Set.** The air handler goes where the furnace stood, connected to the existing supply and return plenums or new ones. The outdoor unit is set on a level pad that drains defrost water away from the foundation. 2. **Braze.** The refrigerant lines are brazed at both ends. If the old line set is the wrong size or in poor condition, it is replaced rather than reused. 3. **Electrical.** The outdoor unit gets its disconnect and circuit, and the air handler its supply. Panel work, if the quote included it, is done under the electrical permit. ### Afternoon: proving it is sealed and charged 1. **Pressure test.** The new lines and coil are pressurized with nitrogen and watched for any drop that would mean a leak. 2. **Evacuation.** A vacuum pump pulls air and moisture out of the system before refrigerant is released or added. 3. **Charge and airflow check.** With the system running, the charge is checked against the manufacturer’s targets and airflow is measured at the air handler. 4. **Controls.** A new thermostat is installed. Title 24 requires a digital setback thermostat whenever a refrigerant component is replaced, and SMUD’s rebate requires a Wi-Fi seven-day programmable connected thermostat. A straightforward conversion in the same locations often fits in a day or two. New ducts, a panel upgrade or a new outdoor location add time. Planning a conversion? Tell us about the furnace, the air conditioner and the house, and a contractor will set up the first visit. ## After the day: verification and handoff ### The ECC-Rater visit Title 24 requires an independent ECC-Rater to verify a ducted heat pump change-out. The rater tests duct leakage against a target of 10% total or 7% to the outside, verifies the refrigerant charge and airflow, and registers the results on the CF3R form. Ducts that fail are sealed and retested. For a SMUD rebate the system must pass this verification. ### Final inspection The building inspector checks the installation against the permit. City of Sacramento change-out permits commonly note that carbon monoxide and smoke alarms are required, so it helps to check those before the visit. ### The thermostat walkthrough The last step is showing the owners how the system behaves. A heat pump sends milder air for longer than a furnace did. On foggy winter mornings it will run defrost cycles, with steam off the outdoor unit and a short pause in heating. Backup heat should be set to come on only when it is needed. The [installation process guide](https://tulesacramentoheatpump.com/guide/heat-pump-installation-process/) covers each stage in more detail, and the [electrical panel guide](https://tulesacramentoheatpump.com/guide/heat-pump-electrical-panel/) explains when the panel becomes part of the job. ### The rebate paperwork For SMUD customers, the participating contractor submits the rebate once the permit is closed and the verification has passed; SMUD also allows the contractor to offer the rebate upfront. The [SMUD rebate guide](https://tulesacramentoheatpump.com/guide/smud-heat-pump-rebates/) covers eligibility. ## Questions about this post ### Does the house stay without heat or cooling while a conversion is underway? For part of it, yes. The old furnace and air conditioner come out before the new system is running, so there is a gap between shutdown and commissioning. It is shorter for a straight swap in the same locations and longer when ducts or a panel are part of the job. Ask for the planned shutdown window in the quote so you can pick a mild week if the old system still works. ### Why does the installer pull a vacuum on the new refrigerant lines? Air and moisture left inside the lines can react with the refrigerant and oil and shorten the compressor's life, and a leak found later means a second visit. After brazing, the lines are pressure-tested to find leaks, then evacuated with a vacuum pump to remove air and moisture before the refrigerant is released or added. ### Do I need to be home for the ECC-Rater visit? Usually someone needs to let the rater in, because the tests run at the air handler, the registers and the outdoor unit. The rater tests duct leakage, refrigerant charge and airflow and registers the results. Ask the contractor who schedules the visit and whether the inspector and the rater can come the same day. Want this answered for your house? Call with your current system, the rooms that bother you and your ZIP code. ## Keep reading - Learn [What happens during a heat pump installation, step by step?](https://tulesacramentoheatpump.com/guide/heat-pump-installation-process/)The order a ducted heat pump job follows from the first look at the house to the final inspection, what each step depends on, and where Title 24 testing and the permit fit in. - Cost Guide [How much does it cost to convert a gas furnace to a heat pump in Sacramento?](https://tulesacramentoheatpump.com/guide/gas-furnace-to-heat-pump-conversion-cost/)What a furnace-and-AC to heat pump conversion typically costs around Sacramento, which parts of the job carry a public figure, what the gas side adds, and how SMUD's gas-to-electric rebate changes the net. - Learn [What does a heat pump permit in Sacramento involve, and what does Title 24 check?](https://tulesacramentoheatpump.com/guide/heat-pump-permit-title-24/)The permit office for each part of the region, what the City of Sacramento's standard change-out permit allows, every Title 24 test a change-out carries, and how SB 222 reshapes permits from 2027. - Learn [When does a heat pump need an electrical panel upgrade?](https://tulesacramentoheatpump.com/guide/heat-pump-electrical-panel/)What a heat pump adds to a home's electrical load, how a service-load calculation decides whether the panel can carry it, what an upgrade typically costs, and where SMUD's panel and circuit rebates fit. - Learn [How do you compare heat pump quotes in Sacramento?](https://tulesacramentoheatpump.com/guide/how-to-compare-heat-pump-quotes/)A line-by-line checklist for putting bids side by side, the questions that expose a missing scope, what the SMUD rebate wording should say, and how to use SMUD's published median as a sanity check.