A Salt Lake City customer in a 1908-built Avenues bungalow contacted us about adding cooling capability to their historic home. The home had operated on hot-water boiler heating with cast-iron radiators since original construction (multiple boiler replacements over the decades, most recent in 2015). Summer cooling had been managed through window units and fans, but the customer wanted modern central cooling without compromising the home’s historic character or undertaking destructive central AC retrofit.
This case study documents the multi-zone mini-split installation that delivered modern cooling and supplemental heating while preserving the home’s architectural character.
Customer Situation
- Home: 1908-built Salt Lake City Avenues bungalow, approximately 1,650 sq ft on two levels
- Existing heating: 2015 modulating condensing boiler with cast-iron radiator distribution (excellent condition)
- Existing cooling: Window units and fans only
- Architectural constraints: Historic plaster walls, exposed wood trim, original wood floors, period architectural details to be preserved
- Customer priorities: Modern central cooling, preserve home character, supplemental heating capability for shoulder seasons
Why Central AC Wasn’t the Answer
Central AC retrofit was discussed and rejected:
- Would require significant duct chases through finished interior spaces
- Plaster wall demolition for supply registers
- Loss of architectural character through soffits and bulkheads
- Major construction project disruption
- Estimated cost: $35,000-$50,000+ with extensive interior work
Mini-split solution:
– No ductwork required
– Minimal interior impact (wall-mounted indoor units)
– Independent zone control per area
– Modern technology with proven reliability
– Heat pump operation provides supplemental shoulder-season heating
– Estimated cost: $15,500 (less than half of central AC retrofit)
System Design
4-zone Mitsubishi Diamond Contractor system:
- Outdoor unit: Mitsubishi MXZ-4C36NAHZ (36,000 BTU multi-zone heat pump)
- Indoor units (4):
- Zone 1 — Main living room: MSZ-FH09NA (9,000 BTU wall-mount)
- Zone 2 — Dining room/kitchen area: MSZ-FH09NA (9,000 BTU wall-mount)
- Zone 3 — Master bedroom: MSZ-FH09NA (9,000 BTU wall-mount)
- Zone 4 — Second bedroom + small office: MSZ-FH09NA (9,000 BTU wall-mount)
Indoor unit placement coordinated with customer to minimize visibility while maintaining functionality.
Installation
Crew: Travis Hollings (lead installer), Mike Reyes, Cole Bennett
Duration: 3 days
Carefully routed line sets through wall cavities and along exterior walls with line set covers matched to home color. All penetrations sealed and trimmed to match existing architecture. No damage to historic plaster work.
Commissioning
All four zones commissioned individually with manufacturer-specified procedures. Wi-Fi adapter installed for Mitsubishi Kumo app control. Customer trained on operation across both cooling and heating modes.
Final Cost and Rebate Filing
Customer’s cost: $15,500
Rebates filed:
– Federal 25C tax credit: $2,000 (heat pump qualifying)
– Rocky Mountain Power Wattsmart heat pump rebate: $400
Effective net cost: $13,100
Customer Outcome
First summer: All four zones maintained comfortable temperatures during peak heat. Boiler heating retained for primary winter heating; mini-split heating useful for shoulder seasons (spring and fall) when running the boiler would heat the whole home for a few cool rooms.
Customer assessment: “Best HVAC decision I’ve made on this house. The home looks the same but is comfortable year-round.”
What This Case Study Demonstrates
- Mini-splits as preferred solution for historic homes vs. destructive central AC retrofit
- Multi-zone configuration delivers independent room control
- Coexistence with existing boiler heating — best of both technologies
- Cost advantage — half the cost of central AC retrofit
- Federal heat pump tax credit ($2,000) applies to qualifying mini-split installations
Historic Home?
If you have a historic Salt Lake City home and want cooling without compromising character, call (385) 250-0687.
- Phone: (385) 250-0687
- Address: 4454 Manhattan Ct, West Valley City, UT 84120