A Kearns customer in a 1958-built single-story home had operated on a rooftop swamp cooler since the home was built — original Kennecott-era housing with cooling adequate for the era but increasingly inadequate as expectations and conditions shifted. The swamp cooler was on its third motor and second pump over the years, and the customer was ready to commit to central AC after years of considering the conversion. Their existing 2015-installed gas furnace was still functional and could serve as the air handler for the new AC, eliminating one major equipment expense from the project.
This case study documents the swamp cooler to central AC conversion process from initial assessment through final commissioning — a project type common in older Kearns housing stock.
Customer Situation
- Home: 1958-built Kearns single-story, approximately 1,320 sq ft (original Kennecott-era housing)
- Existing furnace: 2015 Goodman 96% AFUE condensing furnace, 60,000 BTU input, still in good operating condition
- Existing cooling: Original rooftop swamp cooler (multiple repairs over decades, currently on third motor)
- Symptom: Inadequate cooling during hot summers; high humidity output from swamp cooler aggravating allergies; aging cooler showing signs of imminent failure
- Customer priorities: Complete conversion to refrigeration cooling, eliminate swamp cooler maintenance, reduce indoor humidity during summer
Initial Assessment
On-site assessment (60 minutes):
Swamp cooler condition:
– Original rooftop unit, multiple component replacements over years
– Current motor: third replacement, 8 years old
– Current pump: second replacement, 4 years old
– Pads: replaced annually
– Mounting platform showing roof deterioration around penetrations
– Water supply line acceptable, drain operating
Furnace condition:
– 2015 Goodman 96% AFUE, well-maintained
– Existing plenum has space for evaporator coil installation
– Blower CFM specifications adequate for 2.5 ton AC
– Electrical service to furnace adequate; AC requires separate 240V circuit
Electrical service:
– 100-amp main panel (typical for vintage home, not upgraded)
– Existing load: approximately 65 amps connected
– AC compressor addition: 16 amps at 240V
– New service load after AC: 81 amps — within 100-amp service capacity
– Available panel space for new 240V circuit: yes
Outdoor unit placement options:
– East side of house: shaded morning, good for compressor longevity, away from bedroom windows
– Customer selected east side placement
Project Scope
The conversion involved more than swamp cooler removal and AC installation:
Work scope:
-
Swamp cooler removal:
– Disconnect water supply line (cap at branch line below)
– Disconnect electrical (remove from circuit)
– Remove drain line
– Crane removal of rooftop unit
– Repair roof penetrations (3 penetrations: cooler base, water supply, drain) with new shingle work and weather sealing
– Remove cooler-specific ductwork branch from existing duct system -
Outdoor AC unit installation:
– Prepare concrete pad on east side of house (8″ gravel base, 4″ 3,500 psi concrete pad)
– Install Trane XR16 2.5 ton condenser (16 SEER2 two-stage)
– Install electrical disconnect at outdoor unit -
Refrigerant line routing:
– Cut 3″ diameter penetration through east wall above outdoor unit
– Route 3/8″ liquid and 7/8″ suction lines through wall cavity, attic space, down to furnace location
– Line set length: approximately 38 ft -
Evaporator coil installation:
– Cut and prepare supply plenum for evaporator coil installation
– Install Trane 4TXC matching evaporator coil
– Resize plenum opening if needed for proper airflow -
Condensate drainage:
– Install primary drain line from evaporator coil to existing floor drain (gravity drain available)
– Install secondary drain pan beneath evaporator coil with float switch for safety shutdown -
Electrical work:
– Install new 240V 30-amp circuit from main panel to outdoor unit
– Wire low-voltage control from furnace control board to outdoor unit -
Thermostat:
– Existing thermostat heating-only; upgrade to cooling-compatible smart thermostat
– Customer selected Ecobee Smart for proper two-stage AC configuration
Installation Schedule
Project duration: 2 days
Day 1 — Swamp cooler removal and rough-in:
– Swamp cooler disconnect and crane removal (morning)
– Roof penetration repair (afternoon)
– Concrete pad pour (afternoon, allowed to cure overnight)
– Penetration cut and refrigerant lineset rough-in
– Electrical rough-in to outdoor unit location
Day 2 — Equipment installation and commissioning:
– Outdoor condenser placement on cured pad
– Evaporator coil installation in supply plenum
– Refrigerant connections with nitrogen purge during brazing
– Condensate drainage installation
– Electrical connections finalized
– System evacuation to 425 microns held 30 minutes
– Refrigerant charge by weight
– Smart thermostat installation and configuration
– Complete commissioning measurements
Commissioning Measurements
After installation and 25 minutes of run-time stabilization:
- Outdoor temperature: 92°F
- Indoor temperature: 75°F (setpoint 74°F)
- Suction pressure: 136 psi ✓
- Discharge pressure: 372 psi ✓
- Subcool: 10°F ✓
- Temperature differential across evaporator coil: 21°F ✓
- Static pressure: 0.39″ wc ✓
- Compressor amp draw stage 1: 6.4 amps; stage 2: 10.8 amps ✓
- Drain line flow: verified by drain pan flooding test
- Float switch operation: verified by simulated drain blockage
- Smart thermostat: two-stage AC operation confirmed
Final Cost and Rebate Filing
Customer’s project cost:
– AC equipment and installation: $9,200
– Swamp cooler removal and roof repair: $1,800
– Smart thermostat: $250 (customer-supplied unit, install only)
– Total: $11,250
Rebates filed on customer’s behalf:
– Federal 25C tax credit: $600
– Rocky Mountain Power Wattsmart AC rebate: $150
Total incentives: $750
Effective net cost after incentives: $10,500
Customer Outcome
First-summer feedback (3 months after installation):
Comfort improvements:
– Indoor temperature consistently 74°F during peak summer days (vs. 80–84°F with swamp cooler)
– Indoor humidity averaged 48% (vs. 65% with swamp cooler)
– Customer reported significant reduction in summer allergy symptoms (associated with reduced indoor humidity)
– Sleep quality improved due to consistent cool, dry indoor air
Operating cost differences:
– Electric bill July-September averaged $85/month higher than prior year (refrigeration uses more electricity than evaporative cooling)
– Water bill: $25/month lower (no swamp cooler water consumption)
– Net summer operating cost increase: approximately $60/month vs. prior swamp cooler
– Customer assessed this as worthwhile given comfort and allergy improvements
Maintenance differences:
– No annual pad replacement
– No annual startup/shutdown service for swamp cooler
– No mid-season repairs for swamp cooler pumps or motors
– Annual AC maintenance through enrolled plan ($95 tune-up + $99 diagnostic if needed)
– Net maintenance cost reduction: approximately $200/year vs. swamp cooler service history
Long-term economic comparison:
– Higher operating cost during summer (~$240/year)
– Lower maintenance cost (~$200/year reduction)
– Net annual cost increase: ~$40/year vs. swamp cooler operation
– Customer’s assessment: comfort improvements and reduced allergy impact justify the modest cost increase
What This Case Study Demonstrates
- Swamp cooler conversion scope — proper conversion includes roof repair, electrical verification, refrigerant line routing, evaporator installation, drainage management, thermostat upgrade — not just outdoor unit installation
- Existing furnace utilization — leveraging 2015 furnace as air handler eliminated equipment expense; furnace replacement would have added $5,500–$11,000 to project
- Realistic cost comparison — refrigeration cooling has higher operating costs than evaporative, but comfort and humidity benefits often justify the difference
- Honest economic analysis — customer informed that summer electric bills would increase before installation; outcomes matched expectations
- Electrical service verification — 100-amp service sometimes accommodates AC addition; sometimes requires upgrade; calculation-based verification prevented mid-project surprise
- Comfort improvements quantified — temperature 6–10°F lower and humidity 17% lower than swamp cooler operation; specific allergy symptom reduction
Considering Similar Conversion?
If you have a swamp cooler in your Kearns home and are considering conversion to central AC, contact us or call (385) 250-0687. We perform complete project scoping including electrical service verification, furnace assessment, outdoor unit placement evaluation, and proper roof repair after swamp cooler removal.
- Phone: (385) 250-0687
- Address: 4454 Manhattan Ct, West Valley City, UT 84120