How tankless actually works
Cold water enters the unit. Gas burners ignite. Water flows past a heat exchanger and heats to setpoint as it flows through. No storage tank.
Unit capacity is measured in GPM (gallons per minute) at a specific temperature rise. "5.1 GPM" usually means at a 70°F rise. In Utah winter, incoming water is 45°F. To get 115°F shower water, you need 70°F rise. Match.
In Utah summer, incoming is ~60°F. Same shower needs 55°F rise — unit can deliver more GPM because the rise is smaller.
Pros and cons
Pros
- Endless hot water within GPM capacity — back-to-back showers, no recovery time
- 15-25% gas savings vs standard tank (no standby losses)
- Space savings — wall-mounted, ~2 sq ft footprint
- Longer lifespan — 15-22 yr vs 10-14 for tanks
- Federal tax credit may apply on qualifying high-efficiency units
Cons
- Higher install cost. $3,800-$6,800 installed vs $1,400-$2,400 for a standard tank
- Cold-water sandwich — brief cold burst when restarting after a pause
- Limited simultaneous flow. Two showers + dishwasher may exceed unit capacity
- Hard water sensitivity. Utah's hard water requires annual descaling on tankless ($180-$280)
- Electric dependency. Power outage = no hot water (some tanks keep working briefly)
- Cold groundwater hurts capacity. Utah winter water is 45°F. Unit GPM rating drops vs warmer regions.
Two scenarios where we DON'T recommend tankless
1. Large family, peak demand
4+ person household, 3+ bathrooms, simultaneous morning routine (showers + dishwasher + laundry). Even a high-end tankless struggles. Tank water heater with high recovery rate, or tank + boiler indirect, handles peak demand better.
2. Low-use vacation home
Tankless makes sense when you use a lot of hot water. For a vacation home used 30 days/year, the savings don't justify install cost. Standard tank + insulation jacket is a cheaper, simpler answer.
When tankless is the obvious move
- Small to mid-size home, 1-3 person household
- Tight space — closet utility, condo, townhouse
- You take long showers or back-to-back family showers
- Replacement is overdue anyway — incremental cost over a new tank is reasonable
- You're OK with annual descaling maintenance
Utah-specific considerations
- Cold groundwater (45°F winter): derates tankless capacity. Plan for 80% of rated GPM in winter.
- Hard water: scale buildup on the heat exchanger is faster. Annual descaling is mandatory, not optional. Skip it and your tankless lasts 6 years instead of 18.
- Altitude (Park City, Wasatch Back): proper altitude commissioning required. Generalist installers often skip this; we don't.