Location: SE Cedar Falls Way, North Bend, WA 98045
Call Date: May 13, 2026
First Visit: May 15, 2026
Work Start: June 8, 2026
Project Completion: June 11, 2026
Lead Technician: Eli, 10 years of experience, Seattle refrigeration certified, EPA 608, Mitsubishi Diamond certified
System Before: Ameristar 4-ton gas furnace and central AC, original 2016 builder installation, undersized and improperly ducted
System After: Mitsubishi MXZSM60NLHZ 5-ton heat pump, dual ducted air handlers (SVZAP36NL 3-ton downstairs, SVZAP30NL 2.5-ton upstairs), PAC-MKA33BC 3-port branch box, full crawl space duct replacement, all-new attic duct system
Final Project Cost: $53,226.50 after $400 PSE rebate (HVAC) + $4,525.12 Navien tankless water heater replacement
The House Was Nine Years Old. The Family Had Never Once Been Comfortable in It.
When Dan called Product Air on May 13, 2026, the complaint wasn’t a furnace that had finally worn out or a compressor that seized after 9 years of hard use. His home on SE Cedar Falls Way in North Bend (4,260 square feet, five bedrooms, two stories, built in 2016), was barely nine years old, and the Ameristar gas furnace and 4-ton central air conditioning system had been there since the builder handed over the keys. The equipment wasn’t at the end of its life. It had been wrong for the house from the day it was installed, and the family had been working around its limitations ever since.
The problem was consistent: not enough air coming out of the vents, especially upstairs, and temperature swings between floors that made the house feel like two separate environments. On a warm summer afternoon, the main floor would cool to something livable while the upper bedrooms stayed stuffy and hot. In winter, the dynamic reversed: heat would pool on the first floor while the master bedroom and the kids’ rooms ran noticeably colder. With five bedrooms spread across two stories, every degree of difference was something the family felt every day.
Dan found Product Air on Facebook and wasn’t looking for a repair quote. He had already concluded that what he had wasn’t going to get better. He wanted to understand what was actually wrong and what it would cost to fix it properly.
The original 4-ton builder-installed condenser at SE Cedar Falls Way, North Bend, WA 98045, set into a wood deck cutout, which restricts drainage and airflow. A telling sign of the installation standard throughout the house.
How a 2016 Home Ends Up With a Broken HVAC System
Eli arrived for the first visit on May 15, 2026. Ten years in the industry, Seattle refrigeration certification, EPA 608, Mitsubishi Diamond certified, Eli doesn’t walk into a house looking for the single thing that’s wrong. He walks in looking for the pattern: what was done, why it was done that way, and what it has cost the people living there.
What he found in Dan’s house told a clear story, and none of it was about age.
The Ameristar furnace ran at 96% AFUE on the data plate: the rating was fine. The air conditioning unit was 4 tons, which sounds adequate until you’re standing in a 4,260-square-foot, two-story home in North Bend with five bedrooms and a layout that spreads the thermal load across both floors. A 4-ton system at that square footage was undersized from the start, and whoever designed the duct system around it didn’t compensate for the shortfall.
They compounded it.
In the crawl space beneath the first floor, the original duct installation showed exactly the kind of workmanship that produces the symptoms Dan had been describing since move-in. Flex duct runs with inadequate support, insulation that had partially separated from the duct body and was no longer maintaining its R-value, and a layout that hadn’t been designed to balance supply air across the downstairs rooms: all of it contributing to the weak pressure at vents that Dan had noticed but had no real explanation for until Eli got underneath the house. The upper floor had no dedicated duct system serving it independently. Conditioned air had to travel from the downstairs equipment, through the crawl space and up through the walls, arriving at upper-floor registers with whatever pressure and temperature remained after that journey.
The original Ameristar air handler in the garage utility closet, SE Cedar Falls Way, North Bend, WA 98045. The equipment wasn’t catastrophically degraded. It was wrong for the house from the day it was installed.
Crawl space ductwork from the original 2016 installation, with insulation pulling away from the duct body. Runs in this condition lose meaningful efficiency and air volume before they reach the registers.
Eli’s read on the cause was direct: the contractor who built the system had prioritized completing the installation over ensuring the house would actually work. The decisions of undersizing the equipment, laying ductwork without balancing it, and setting a condenser unit into a wood deck cutout were the decisions of someone who knew they would never be held accountable for how the house felt on the inside.
Dan also mentioned that the Navien tankless water heater had been giving the family trouble. It wasn’t the reason for the call, but Eli noted it and added a replacement option to the estimate alongside the HVAC work.
The full crawl space under Dan’s North Bend home before remediation: original duct layout, inadequate support, and a vapor barrier that had seen better days.
Six Options, One Conversation, One Family Decision
Eli presented the full range of options on the day of the first visit. All six were designed and priced on-site, running from the most practical baseline to the most comprehensive solution available for a home of this size. The conversation didn’t start with price. It started with what the family actually wanted: an even temperature throughout the house, upstairs and downstairs, in every season, without managing which rooms were usable based on what the HVAC was doing that day.
- Navien 199k Tankless Water Heater Replacement: $4,525.12
- Trane 5-Ton Standard Dual Fuel, upgraded crawl space ductwork and equipment sizing: $33,465.68
- Trane 5-Ton Variable Speed Dual Fuel, upgraded crawl space ductwork and equipment sizing: $37,129.88
- Mitsubishi Single 5-Ton System, upgraded crawl space ductwork and equipment sizing: $43,668.77
- 2 Mitsubishi Indoor Systems with 1 Heat Pump, upstairs and downstairs split into 2 independent zones, upgraded crawl space ductwork, all-new attic duct system, upgraded equipment sizing: $58,123.34 (Chosen)
- Ideal Home Comfort, 2 completely independent systems: $67,121.47
The gap between option 4 and option 5, $43,668.77 versus $58,123.34, comes down to one structural question: do you put one system in charge of the entire house, or do you split the house into two independently controlled thermal zones? Option 4 would have replaced the equipment and fixed the crawl space ductwork. It would have been a substantial improvement. But it would have left the family with a single thermostat reading one location and one system trying to satisfy the thermal demands of two very different floors.
Dan said option 5 felt like the right balance of investment and what the family actually needed. He didn’t explain it in technical terms. Nine years in a house that had never been right was explanation enough.
Why One System Serving Two Floors Is Often the Wrong Tool for a Two-Story Home
The most consistent complaint we hear from homeowners with two-story houses in the Snoqualmie Valley, North Bend, Snoqualmie, Fall City, Issaquah, is some version of what Dan described: one floor is comfortable, the other never quite is, and nothing that gets adjusted on the thermostat or at the registers makes the difference go away. It is one of the most common HVAC complaints in the Pacific Northwest, and it has a structural cause.
Heat moves in predictable patterns. In a two-story home, this often creates a consistent challenge: the upstairs tends to run warmer than the rest of the house. In summer, the upper floor absorbs solar heat through the roof and sits above rising warm air, making it harder to keep comfortable. In winter, the opposite effect can occur: heat generated on the first floor rises and lingers upstairs, which can leave the lower level feeling properly regulated while the upper level becomes overheated. A single-zone HVAC system with one thermostat typically located downstairs only measures and responds to the first-floor temperature. As a result, it often cools or heats the lower level correctly while the upstairs remains out of balance.
The standard response from a builder’s contractor is to oversize the duct runs to the underperforming zone and rely on register damper adjustments to push more air where it’s needed. That’s a workaround, and in Dan’s house, it wasn’t even done competently: the duct system was undersized throughout, and the upper floor had no independent duct runs at all.
A two-zone ducted system is structurally different. The Mitsubishi approach here places a 3-ton SVZAP36NL air handler in the downstairs mechanical room and a 2.5-ton SVZAP30NL air handler in the attic, each serving its floor with a dedicated duct system, a dedicated thermostat, and its own refrigerant circuit from the outdoor MXZSM60NLHZ unit through the PAC-MKA33BC branch box. The outdoor unit’s modulating variable-speed compressor reads the demand from both zones simultaneously and adjusts its output in real time, running at partial capacity when one zone is satisfied, increasing when both are calling, and never short-cycling because one thermostat satisfied before the other. This is the mechanical reason the two-zone configuration solves a problem that a single-zone upgrade cannot.
The upgraded filtration built into both air handlers addresses something Dan’s family had lived with but may not have framed as an HVAC issue: the wildfire smoke that moves through the Snoqualmie Valley during late summer. The original duct system with its unsealed connections, separated insulation, and no serious filtration recirculated whatever made it into the air stream.
The new system, with sealed crawl space and attic duct runs and upgraded filtration media on both handlers, treats the air before it reaches the living spaces. For a family in North Bend, with five bedrooms and children in the house, that matters year-round and especially in August and September.
The PSE rebate of $400 applied here, through the Puget Sound Energy Mitsubishi program for systems rated above HSPF2 8.5 is a smaller number than you’ll see on some heat pump installs. The reason is the starting fuel type: larger PSE rebates of $1,200 to $4,000 are available for homes converting from oil or electric resistance to a heat pump, because those conversions produce the greatest emissions and utility demand reduction. Dan’s home was already on a gas furnace with central AC, so the fuel-switching incentive programs don’t apply at their full value. The $400 efficiency rebate for systems exceeding the HSPF2 8.5 threshold is the applicable program, and it was applied. If you’re comparing this case to others where rebates appear larger, that’s the difference.
What We Installed
The core of this system is the Mitsubishi MXZSM60NLHZ: a 5-ton, 60,000 BTU Ultra Quiet Side Discharge heat pump with a modulating variable-speed compressor. It doesn’t stage on at a fixed capacity and bang off when the thermostat satisfies. It runs at whatever fraction of its total output the combined zone demands, adjusting continuously, maintaining temperature with less swing and less mechanical wear than any single-stage system can produce.
From the outdoor unit, refrigerant runs to the PAC-MKA33BC three-port branch box in the attic, which routes independent circuits to each air handler: the SVZAP36NL 3-ton unit in the downstairs mechanical room, serving the main living areas through the fully rebuilt crawl space duct system, and the SVZAP30NL 2.5-ton unit in the attic, feeding the all-new upstairs duct system that now reaches every upper-floor bedroom and the bonus room. Two Mitsubishi Kumo Cloud wall controllers, one per floor, give the family independent setpoints on each level, accessible remotely and settable by room schedule if they choose to use that capability.
| Component | Detail |
| Outdoor Heat Pump | Mitsubishi MXZSM60NLHZ, 5-ton / 60,000 BTU, Ultra Quiet Side Discharge, modulating variable-speed |
| Branch Box | PAC-MKA33BC, 3-port multi-zone refrigerant distribution |
| Downstairs Air Handler | Mitsubishi SVZAP36NL, 3-ton / 36,000 BTU, modulating variable-speed, communicating |
| Upstairs Air Handler | Mitsubishi SVZAP30NL, 2.5-ton / 30,000 BTU, modulating variable-speed, communicating |
| Zone Controls | Mitsubishi Kumo Cloud wall controllers, 1 per zone |
| Crawl Space Ductwork | Full removal and replacement: properly sized, supported, and insulated |
| Attic Ductwork | All-new second-floor duct system, new runs and supply registers throughout upper level |
| Filtration | Upgraded media filtration on both air handlers |
| Navien Tankless Water Heater | Replacement unit, 199,000 BTU |
| Manufacturer Warranty | 12 years |
| Product Air Labor Warranty | 5 years, no strings, no fine print |
The Mitsubishi MXZSM60NLHZ 5-ton heat pump installed at SE Cedar Falls Way, North Bend, WA 98045, June 2026. Line set run in white conduit up the exterior wall: clean, serviceable, properly set away from the original deck location.
Installation Timeline
May 15, 2026 — Consultation and System Design
Eli walked the entire house, measured each room, assessed the crawl space duct condition in full, and identified the scope of the attic work needed to create an independent upper-floor zone.
All six options were designed and priced on-site. Dan reviewed them that day and made his decision before Eli left.
Product Air handles all permitting for projects of this scope. Mechanical and electrical permits for a heat pump replacement with full duct work and new system installation in King County typically run several hundred dollars depending on project valuation and scope. Permits were submitted the same week and were in hand within 24 hours.
June 8–11, 2026 — HVAC Installation (2 Technicians, 4 Days)
Day one of installation began with removal: the Ameristar furnace came out of the mechanical room, the old condenser was extracted from its deck cutout, and the original crawl space duct runs were pulled. The two-man HVAC crew then moved into the crawl space to lay new ductwork: properly sized metal and flex runs, correctly supported at proper intervals, insulated to current standards, and laid out to balance supply airflow across all first-floor rooms for the first time in the house’s history.
Simultaneously, the attic work began: the SVZAP30NL was staged into the attic and set on a support platform between the roof rafters, refrigerant line set was run from the outdoor unit through the PAC-MKA33BC branch box to the attic handler, and all-new duct runs were fabricated and connected to reach every upper-floor bedroom and the bonus room.
Airflow commissioning data from the bonus room: 388.53 cfm, 302 fpm flow velocity, 72.4°F supply air temperature. Measured at project close, SE Cedar Falls Way, North Bend, WA 98045.
Commissioning included individual room-by-room airflow verification. The bonus room, one of the harder-to-reach spaces in the attic zone and historically one of the most uncomfortable rooms in the house, measured 388.53 cfm at 302 feet per minute flow velocity at 72.4°F supply air temperature on the Testo 410i. The duct design delivered to spec.
The PAC-MKA33BC three-port branch box in the attic, the connection point that routes refrigerant from the single outdoor unit to both the upstairs and downstairs air handlers independently.
The Mitsubishi SVZAP36NL 3-ton air handler in the downstairs mechanical room, replacing the original Ameristar unit. SE Cedar Falls Way, North Bend, WA 98045, June 2026.
New supply register in an upper-floor bedroom — part of the all-new attic duct system that serves the second floor independently for the first time since the house was built.
June 8, 2026 — Electrical (2 Electricians, 1 Day)
A two-person electrical crew ran dedicated circuits for the outdoor unit and both air handlers, properly sized for the load and routed cleanly to the panel. The electrical work ran concurrently with the HVAC crew on the first day of the install.
June 11, 2026 — Inspection and Sign-Off
The King County inspector reviewed the mechanical and electrical work on the final day. Both permits (electrical and mechanical) were signed off the same day. The system was fully commissioned before the inspector left the site.
Price and Rebate Transparency
| Program | Amount |
| Puget Sound Energy: Mitsubishi Rebate, HSPF2 above 8.5 | $400 |
| Total Rebates | $400 |
HVAC Base Price: $53,626.50
Final HVAC Cost After Rebates: $53,226.50
Navien 199k Tankless Water Heater Replacement: $4,525.12 (separate project)
Payment: Credit card
The $400 PSE rebate is the correct number for this project, and we don’t want it to look bigger than it is. The fuel-switching rebates that can reach $1,200 to $4,000 from Puget Sound Energy apply when a home is converting from oil heat or electric resistance to a heat pump, those conversions produce the largest measurable reduction in energy demand and emissions on the grid.
Dan’s home ran a gas furnace with central AC, so the conversion rebate programs apply in a reduced form. The HSPF2 efficiency rebate at $400 is what this equipment qualifies for, and it was applied at the time of installation. If you’re doing this project from an oil furnace starting point, the rebate landscape looks meaningfully different, but that wasn’t the case here, and we don’t obscure it.
The Long-Term Picture
A Mitsubishi variable-speed ducted heat pump system of this specification carries a realistic service life of 15 to 20 years in the Pacific Northwest when properly installed and maintained. The MXZSM60NLHZ modulates its compressor speed to match the combined load from both zones, which means it operates at partial capacity the majority of the time gentler on the compressor, quieter from the exterior, and more precise in maintaining set temperatures without the swings that come from a system cycling on and off at full output.
The comparison to the Ameristar setup is concrete. A 4-ton single-stage gas furnace and AC running at a fixed capacity operates at the same output regardless of whether the house needs all of it: short cycling in mild weather, delivering temperature swings at the thermostat, and wearing the contactor and blower motor faster than a modulating system would. The MXZSM60NLHZ at 30% capacity on a mild spring afternoon delivers a slow, steady supply of conditioned air to both zones and virtually no temperature swing from setpoint. Over a 15-year service life, the difference in compressor starts and average amp draw is not trivial.
The 12-year manufacturer warranty on the Mitsubishi equipment and the 5-year Product Air labor warranty without fine print or exclusion clauses align with the expected service life of the system in a way that matters practically: the family is covered through the period when any installation issue, component defect, or commissioning oversight would show up. If something installed by our crew fails within five years, we return and fix it. No service call charge, no diagnosis fee, no argument about what’s covered. That’s what the warranty means.
For Dan’s family on SE Cedar Falls Way, the first summer with the new system will answer nine years of questions. Every room on two floors reaching and holding the same temperature. The bonus room, which measured 388 cfm of conditioned supply air at commissioning, compared to whatever was drifting up through the walls before, behaving like a room that belongs in the house. The air quality on the first smoke event of August. These are the things that don’t appear on a spec sheet but are the actual reason a family chooses the $58,000 option over the one that would have gotten them part of the way there.
Key Takeaways
- A home built in 2016 can have a completely dysfunctional HVAC system if the builder’s contractor undersized the equipment and improperly installed the ductwork. Age is not the issue, and nine years of discomfort in a newer home is not unusual when the original installation was wrong from the start.
- A two-zone ducted mini-split system places independent air handlers on each floor with separate duct systems and separate thermostats, which is structurally different from a single-system setup with register balancing and is the only configuration that can hold different setpoints on different floors simultaneously.
- The cost of a dual-zone Mitsubishi ducted system, MXZSM60NLHZ outdoor unit, SVZAP36NL and SVZAP30NL air handlers, PAC-MKA33BC branch box, full crawl space duct replacement, and all-new attic duct system, in a 4,260 sqft two-story home in North Bend, WA 98045 is $53,226.50 installed with permits, after a $400 PSE rebate.
- Replacing the ductwork is the core of the project, not an optional upgrade in a home where the original duct system was undersized and improperly laid out, new equipment in old ducts delivers a fraction of the improvement the new equipment is capable of.
- The PSE Mitsubishi rebate for systems rated above HSPF2 8.5 is $400 in 2026; the larger PSE rebates of $1,200–$4,000 for heat pump installations apply when converting from oil or electric resistance heat, not from a gas furnace and central AC setup.
- Mitsubishi’s 12-year manufacturer warranty on this equipment class, combined with Product Air’s 5-year labor warranty with no fine print, means a family installing this system in 2026 carries no uncovered risk on the installation or the core components through 2031 at minimum.
Product Air in the Snoqualmie Valley
Product Air Heating, Cooling and Electric serves North Bend, Snoqualmie, Fall City, Issaquah, and the communities along the I-90 corridor into Seattle and Bellevue. Dan’s home on SE Cedar Falls Way is exactly the kind of job that shows up regularly in this part of King County: newer construction, real square footage, and an original HVAC installation that was never designed to serve the people who actually live in the house.
The work in cases like this isn’t replacement in the conventional sense. It’s a redesign, figuring out what the home requires floor by floor, building a system around those real requirements, and doing it in a way that will hold for the next fifteen to twenty years. Eli did that here. The family spent nine years in a house that never felt right. That shouldn’t take another nine years to confirm was worth fixing.
— Serge Nikolin, Co-Founder, Product Air Heating, Cooling and Electric
Marysville · Issaquah · Seattle · Western Washington