Whether your water heater has failed, you're replacing it proactively, or you're upgrading to a more efficient unit, installation in a St. Louis home involves factors specific to this market — basement depth, gas line sizing for tankless units, Missouri River sediment levels, and Ameren Missouri and Spire Energy rebate programs. If your current unit might be repairable, see our water heater repair service first.
What Type of Water Heater Should I Install?
Tank Water Heater Installation
The standard for St. Louis homes: a 40–80 gallon storage tank, most commonly natural gas. Quick replacement for existing tank units. Ameren & Spire rebates available on qualifying high-efficiency units.
View Tank Water Heater Installation detailsTankless Water Heater Installation
On-demand heating — no standby heat loss. Gas line upsizing is the most common installation barrier. Spire Energy rebates available on qualifying units.
View Tankless Water Heater Installation detailsHeat Pump Water Heater
Increasingly viable in St. Louis — Missouri's climate supports operation 8–9 months per year. Ameren Missouri offers rebates up to $300. Best for 2–3 person households.
View Heat Pump Water Heater detailsWhich Installation Is Right for Your Home?
"My gas water heater stopped working and I just need a replacement today"
→ You likely need: Tank Water Heater Installation — direct swap, same gas connection
"I want endless hot water and I'm willing to invest in the right setup"
→ You likely need: Tankless Installation — requires gas line assessment first
"I want the lowest operating cost over time and I have a large basement"
→ You likely need: Heat Pump Installation — best efficiency, Ameren rebate available
How Water Heater Installation Works
Assessment
We assess your existing setup: gas line size and BTU capacity, electrical panel availability, water pressure and sediment load from Missouri River supply, basement dimensions, and rebate eligibility under Ameren Missouri.
Installation
Tank: disconnect old, flush and remove, set new, connect gas/water. Tankless: plus gas line upsizing if required, combustion air and exhaust routing. Heat pump: electrical connection, condensate drain, clearance verification.
Test & Documentation
Full hot water draw test, pressure relief valve check, gas leak verification, and documentation for Ameren Missouri or Spire Energy rebate applications if applicable.
What Affects Installation Cost in St. Louis?
Tank (40-gal gas)
$900–$1,400 installed.
Tank (50-gal high-efficiency)
$1,200–$1,800.
Tankless gas
$1,800–$3,200 (varies by gas line work needed).
Heat pump
$1,500–$2,500 before rebates.
Gas line upsizing (tankless)
Upsizing ¾-inch to 1-inch gas line adds $400–$900 depending on run length — the most common hidden cost in tankless installations.
Removal and disposal
Removing and disposing of old unit: $75–$150.
Venting and exhaust routing
Direct-vent tankless units require dual-pipe exhaust. Additional routing adds $150–$400.
Rebate offset
Ameren Missouri: up to $300 on qualifying heat pump units. Spire Energy: rebates on qualifying condensing tankless.
What Our Customers Say
"Had a tankless installed after our tank failed. Plumber checked the gas line first, told us we'd need the line upsized. Whole job done in one day — haven't run out of hot water since."
"Replaced a 20-year-old tank with a heat pump unit. Plumber walked us through the Ameren rebate paperwork. Operating cost has dropped noticeably."
"Old gas water heater failed on a Friday. Called in the morning, had a new 50-gallon high-efficiency unit installed by early afternoon. Plumber explained the sediment flushing schedule for Missouri River water."
Related Plumbing Services
Water Heater Installation Across St. Louis
Water Heater Installation FAQ
Ready to Replace or Upgrade Your Water Heater?
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