Heat pump installation in Mercer Island typically costs between $8,520 and $40,000+, depending on the size of the home, whether one or two systems are needed, equipment tier, electrical work, and available rebates. Most single-system installations range from $19,000 to $28,000 before rebates, while larger homes requiring two systems can exceed $40,000.
The house on Forest Avenue Southeast had been theirs for only a few months. Christopher and his partner had bought it, 8,110 square feet, two stories, four bedrooms, a 2009 build on one of the quieter residential corridors on the island, and walked straight into their first Western Washington winter with an HVAC system that was telling them, in the clearest possible language, that it was done.
Both heat pumps were original to the home’s construction. Both were 17 years old. Both were Carrier systems serving separate zones of a house too large for a single system to handle correctly. One of them had stopped producing heat entirely by the time Christopher called Product Air on December 30. The other was still running, but running in the way old equipment that’s been ignored runs, not failing outright, but offering nothing anyone could rely on.
Eli came out the same day. He walked the house, assessed the systems, and asked the questions he always asks before reaching for a price sheet. “I heard you when you said that you just bought this home,” he told Christopher and his partner after the diagnostic. “I heard that you said it would be nice to never have to cross this situation again. I heard that you said your comfort is important to you.” That framing shaped everything that followed.
They replaced both systems: two Resolute by Trane inverter heat pumps with matching variable-speed air handlers, one at 4–5 tons for the downstairs zone and one at 2–3 tons for the upstairs zone. Four HVAC technicians and two electricians completed both installations in a single coordinated day on January 8. Permits were signed off the following morning. Final cost after $1,900 in PSE rebates: $40,292.49.
That is the upper end of what Mercer Island heat pump installations look like. For the full breakdown of pricing across every equipment tier and installation type in Western Washington, our guide on heat pump installation costs in Seattle covers the complete picture. What this article covers is what changes when the address is on Mercer Island.
What Does Heat Pump Installation Cost in Mercer Island?
Heat pump installation on Mercer Island in 2026 runs from $8,520 for a straightforward entry-level add-on up to $40,000+ for a dual-system full replacement on a large home. Single-system replacements for the more typical Mercer Island housing stock (larger homes, often aging systems, often multi-zone) land most commonly in the $19,000 to $28,000 range before rebates.
| Scenario | Typical Range |
| Entry-level add-on, no electrical work | $8,520 – $10,420 |
| Mid-range single-system replacement | $13,532 – $19,003 |
| Premium Mitsubishi single system | $17,672 – $22,664 |
| Two-system full replacement (large home) | $30,000 – $45,000+ |
| PSE and Energy Smart Eastside rebates (qualifying systems) | Reduce total by $1,500 – $10,000+ |
How Pricing Breaks Down
Equipment accounts for roughly 45% of a typical installation budget, labor around 30%, permits and materials the rest. What moves the total on Mercer Island is almost always the equipment tier and scope because the homes are larger, because multi-zone systems are common, and because the owners here tend to buy a system once and stay with it.
A home over 5,000 square feet with two independent zones needs a different answer from a 1,500-square-foot bungalow with one. The larger the home, the more likely the estimate reflects that scope and the more important it is to see both systems quoted together before committing to either one separately.
Why Are Heat Pump Installations More Expensive on Mercer Island?
Mercer Island homes are not like the neighborhoods we work most frequently in Seattle, and those differences shape every estimate we write here.
The homes are larger. Three thousand to eight thousand square feet is common, and at that size a single system rarely handles both floors cleanly. Multi-zone setups are standard. Any major replacement means assessing two systems at once, which is why the right approach, the one we took with Christopher and with Connor on West Mercer Way, is to quote both systems together, at more than one equipment tier, before the homeowner commits to anything.
The equipment that fits these homes skews toward the upper-mid and premium tiers, and not because of the address. It is about the load. A 3.5-ton Mitsubishi Hyper Heat on a 3,000-square-foot home that’s well-insulated provides meaningfully better comfort and longer service life than running a single-stage system at the edge of its capacity. Variable-speed, modulating equipment ramps to match demand continuously rather than cycling between full blast and off, which is the difference between a home that holds a temperature and one that swings around it.
Noise is a real variable here in a way it is not on a dense Seattle block. Outdoor units on Mercer Island sit close to neighboring properties, often in setback conditions where sound profiles and sightlines both matter. The quiet side-discharge design on the Trane Resolute and the Mitsubishi Hyper Heat line runs significantly quieter than older single-stage equipment under load, and that difference is audible from the yard.
Do You Need a Permit to Install a Heat Pump on Mercer Island?
Heat pump installation on Mercer Island requires permits through the City of Mercer Island’s Community Planning and Development department, filed through the state’s MyBuildingPermit.com portal. Mechanical permits cover the heat pump and air handler work; electrical permits cover any panel or circuit modifications.
Product Air handles all of it as part of every installation: research, application, inspection scheduling, and final sign-off. Neither Christopher’s job nor Connor’s required either homeowner to manage any part of the permit process directly.
Which Heat Pump Systems Do We Recommend?
| Tier | Brand / Model | Add-On, No Electrical | Add-On, With Electrical | Full System, With Electrical |
| Entry | Runtru by Trane, 14 SEER2 | $8,520 | $10,420 | $14,660 |
| Mid | Midea EVOX G3 / Trane Resolute, 15–19 SEER2 | $13,532 – $13,870 | $14,392 – $14,715 | $18,195 – $19,003 |
| Premium | Mitsubishi PUZAK / SUZAK Hyper Heat, variable speed | $16,532 | $17,672 | $20,400 – $22,664 |
Two full systems at the upper-mid tier run at a different scale: $40,292.49 after rebates for a 4–5 ton and a 2–3 ton system replacing a combined 17-year-old setup in a house over 8,000 square feet.
Product Air is a Mitsubishi Diamond Elite Contractor. On Mitsubishi equipment, that certification extends the manufacturer warranty from the standard 10 years to 12. Connor’s install on West Mercer Way used the PUZAK42NLHZ, which carries that 12-year coverage.
What Heat Pump Rebates Are Available on Mercer Island?
Mercer Island is PSE territory. Seattle City Light rebates do not apply here.
PSE rebates. Base PSE rebate: $300 for systems at SEER2 15.2, $600 at SEER2 16 or higher. For hybrid installations, a heat pump paired with a gas furnace, PSE’s program pays $1,500, or $2,400 for income-qualified households. PSE also offers midstream rebates tied to efficiency thresholds above HSPF2 8.5 and 9.5, which applied as separate line items on both jobs below.
Energy Smart Eastside. This is a program that applies to Mercer Island and a handful of other Eastside cities such as Issaquah, Bellevue, Kirkland, Redmond, Sammamish and does not apply in Seattle. The program offers $1,000 to $10,000 depending on household income. An installation on Mercer Island can draw on both PSE’s rebates and Energy Smart Eastside simultaneously when the household and the equipment qualify, which is the rebate combination that applied on Connor’s job.
On Christopher’s two-system replacement: $1,500 PSE hybrid rebate and $400 PSE midstream rebate reduced the final cost from $42,192.49 to $40,292.49.
On Connor’s Mitsubishi Hyper Heat hybrid on West Mercer Way: the PSE hybrid program, the PSE midstream rebate tied to the PUZAK42NLHZ’s HSPF2 9.5+ rating, and the Energy Smart Eastside rebate combined to reduce the total from $21,412.34 to $18,312.34, a total reduction of $3,100 applied at the invoice stage before Connor signed anything.
The federal Section 25C tax credit expired January 1, 2026. Christopher’s installation fell on January 8 if you have an install that landed close to that boundary, confirm eligibility directly with a CPA rather than assuming it applies.
We handle all rebate paperwork. The customer sees the reduced final number on the invoice, not a reimbursement check arriving months later.
Two Real Mercer Island Jobs
Christopher, Forest Avenue SE, Mercer Island 98040, Two-System Trane Resolute Replacement, $40,292.49
New owners, cold house, December 30. Eli came out the same day. Two 17-year-old Carrier systems serving a home over 8,000 square feet, aged and ignored, one no longer producing heat at all. The diagnostic pointed in one direction: both systems needed to go.
Eli laid out four options across two equipment tiers, Trane’s upper-mid tier and Trane’s top-of-catalog, covering both systems together. Christopher and his partner chose the upper-mid tier for both zones.
The Resolute by Trane line: fully inverter-driven and modulating, a meaningful step up from the fixed-stage Carrier systems coming out. Downstairs zone: 4–5 ton heat pump (5HCL5060B1000A) paired with a 5-ton variable-speed air handler (5TDM5D07AC51SA).
Upstairs zone: 2–3 ton heat pump (5HCL5036B1000A) paired with a 3-ton variable-speed air handler (5TDM5C04AC31SA).
Four HVAC technicians and two electricians, one day on site, both systems commissioned and running before the crew left. Permits signed off the following morning. PSE hybrid rebate: $1,500. PSE midstream rebate: $400. Final cost: $40,292.49, paid half by check and half by Visa. Ten-year manufacturer warranty, three-year Product Air labor warranty.
Connor, West Mercer Way, Mercer Island 98040, Mitsubishi Hyper Heat Hybrid, $18,312.34
Connor found Product Air by walking past a crew working on his father’s house on West Mercer Way. He stopped and talked to Dima and Nate on site, and asked to be scheduled for his own estimate.
The 1989 two-story at 3,260 square feet had a 12-year-old Coleman two-stage furnace that was operational but had never been serviced. No air conditioning. Connor had compared three contractors: Belred, Gene Johnson, and Product Air and had a baby arriving in a couple of months, which made the timing matter more than it usually does. Robert came out, assessed the furnace and the electrical, and put together a hybrid option: the Mitsubishi PUZAK42NLHZ, a 3.5-ton Hyper Heat unit, paired with the existing furnace through a Mitsubishi Intelli-HEAT dual-fuel evaporator coil. Central air conditioning the home had never had, plus the Mitsubishi’s heating efficiency through the milder months, with gas backup for deep cold.
Robert’s note on how the estimate was built: “Once we sat down with Connor it was important to get higher efficiency, a good quality system, and the maximum amount in savings.” The Mitsubishi Diamond Elite certification extended the PUZAK42NLHZ’s warranty to 12 years instead of the standard 10.
PSE hybrid rebate, PSE midstream rebate on the PUZAK42NLHZ’s HSPF2 9.5+ rating, and the Energy Smart Eastside rebate combined for a total reduction of $3,100. Final cost: $18,312.34, paid by check. Five-year Product Air labor warranty. “Customer loved how we did the work and helped in rebates.”
What to Know Before Calling
Mercer Island estimates take longer than a standard Seattle visit because the scope question ( one system or two, what zone needs what, how the electrical supports the new load) takes more time to answer correctly on a larger property. We spend that time at the estimate so the quote you receive reflects what the house actually needs. The estimate is free and includes written options at three to four tiers.
Why We Post Real Prices
Connor compared three contractors. He had specific numbers from each, at each tier, across rebate programs. That is the only way a homeowner makes a real decision rather than a pressured one. We gave Christopher and Connor real numbers before either of them committed to anything. That is how we intend to work.
Get a Free Heat Pump Installation Estimate in Mercer Island, WA
Call (425) 340-3710 or reach us through the website. We serve Mercer Island, Issaquah, Seattle, Marysville, and the surrounding area from our warehouses in both Marysville and Seattle.
Frequently Asked Questions
Is Mercer Island served by PSE or Seattle City Light?
PSE. Seattle City Light’s rebates do not apply to Mercer Island addresses.
Does Energy Smart Eastside apply on Mercer Island?
Yes. Mercer Island is one of the covered cities. The program offers $1,000 to $10,000 depending on household income and can stack with PSE rebates on the same installation.
Does a large Mercer Island home need two heat pump systems?
Often yes. A home over 4,000 to 5,000 square feet with two floors typically needs two separately zoned systems, each sized for its load, rather than a single oversized unit trying to condition both floors from one output. We quote both options so you can see the full picture before committing to either.
How long does a Mercer Island installation take?
A single-system replacement runs one to two days depending on electrical scope, with permits signed off the following morning. A two-system replacement, staffed correctly, can still be completed in a single coordinated day.
What is a Mitsubishi Diamond Elite Contractor and why does it matter?
Diamond Elite is Mitsubishi’s highest certification tier, held by a limited number of contractors. It requires ongoing technician training specific to Mitsubishi systems. The practical benefit: a 12-year manufacturer warranty on Mitsubishi equipment instead of the standard 10.
Does Product Air handle permitting on Mercer Island?
Yes. We handle research, application filing, inspection scheduling, and final sign-off on every job. Neither homeowner manages any part of that process.
Is the federal Section 25C tax credit still available?
The credit expired January 1, 2026. Installations completed close to that date should be confirmed with a CPA, not assumed eligible based on when an estimate was written.
Disclaimer
This article is current as of June 2026. All prices are based on Product Air’s real installation experience with equipment and labor costs current as of publication. This is not a binding quote. An accurate price for your specific home requires a free in-person estimate. Rebate program terms, amounts, and eligibility are controlled by the issuing utility or agency and subject to change; verify current terms directly before making purchase decisions.
— Serge Nikolin, Co-Founder, Product Air Heating, Cooling and Electric
Marysville · Issaquah · Seattle · Western Washington