Most AO Smith residential water heater installs are within reach of a handy homeowner — except Voltex hybrid (heat pump), ProLine Tankless, and Cyclone Xi commercial. Those are pro-only.
Before you start
Almost every US jurisdiction requires a permit for water heater replacement. Gas installs always require permit + inspection; many jurisdictions require licensed plumber. Electric installs usually allow homeowner DIY in homeowner-occupied properties. Voltex and tankless typically require licensed installer.
Standard electric tank install (Signature 100 / ProMax electric)
- Shut off power at breaker, verify with voltage tester
- Shut off cold-water inlet
- Drain tank via drain valve to floor drain or hose
- Disconnect electrical conduit, note wire colors
- Disconnect cold inlet and hot outlet
- Slide old tank out, set new on drain pan, verify level
- Connect cold inlet and hot outlet with new flex hoses
- Connect electrical (black-red-white-ground per wiring diagram)
- Install new T&P discharge tube routed downward within 6" of floor
- Open cold inlet, fill tank (open hot faucet to vent air)
- Verify no leaks
- Restore power AFTER tank is full
- Schedule inspection
Standard gas tank install (Signature Premier / ProMax gas)
Same general procedure plus:
- Shut off gas at supply, wait 10 minutes
- Disconnect gas line, install new flex gas connector (NEVER reuse old one)
- Use yellow gas-rated Teflon tape
- Disconnect and reconnect flue or vent — atmospheric must slope upward at 1/4" per foot minimum
- Leak-test every gas joint with bubble solution before lighting
- Light pilot per AO Smith instructions (see our pilot lighting page)
Voltex hybrid install (pro recommended)
- 1,000+ cu ft ambient air at install location
- Condensate drain or pump (2–4 gallons/day)
- 30-amp 240V dedicated circuit
- 7+ ft ceiling clearance (Voltex is taller than standard electric)
- Verify circuit panel capacity — older homes with 100-amp service may need upgrade
ProLine Tankless install (pro recommended)
- 3/4" gas line required
- PVC venting up to 100 ft
- 120V outlet near unit
- Condensate drain
- Service valves for annual descaling
- Permit and licensed installer required in most jurisdictions
Bottom line
Standard like-for-like tank swaps: DIY-friendly. Voltex and ProLine Tankless: pro. For specific AO Smith models see our AO Smith lineup. For installer-network info see AO Smith dealers.