Most Rheem residential water heater installs are within reach of a handy homeowner — but a few configurations (gas valve work, tankless install, ProTerra heat pump) are pro-only territory. This page walks through the install procedure by unit type, covers permits and code, and lists the tools you'll need.
Before you start: permits and code
Almost every US jurisdiction requires a permit for water heater replacement. Specifically:
- Gas water heater installs: permit + inspection required nearly universally. Some jurisdictions require licensed plumber install (no DIY).
- Electric water heater installs: permit usually required; DIY accepted in most jurisdictions if homeowner-occupied
- Tankless installs: permit + inspection. Many jurisdictions require licensed installer for tankless due to gas-line resizing or electrical service upgrades typically involved.
- Sealed-combustion / direct-vent / power-vent: permit + inspection plus vent termination must clear setback distances from windows and intake vents (typically 4 ft minimum)
Check your jurisdiction at the city/county Building Department website before proceeding. Permits typically cost $50–$200 and inspection is scheduled within 1–2 weeks.
Tools needed (electric tank)
- Pipe wrench (14"+)
- Adjustable wrenches (2)
- Voltage tester
- Multimeter
- Garden hose for draining
- Pipe dope or Teflon tape
- Tubing cutter or pipe cutter (if any plumbing modification needed)
- Bucket and rags
- Drain pan
Tools needed (gas tank)
Everything above, plus:
- Gas leak detection solution (or bubble soap)
- Yellow gas-rated Teflon tape (NOT white plumber's tape — must be rated for gas)
- Flexible gas connector (new — never reuse the old one)
- Combustion analyzer (pro-level — for verifying complete combustion)
Electric tank install — step by step
- Shut off power at the breaker for the old unit. Verify with voltage tester at the element terminals.
- Shut off cold-water inlet at the supply valve above the tank
- Drain the old tank via the drain valve to a floor drain or hose to outside
- Disconnect the electrical conduit from the junction box on top of the tank — note wire colors (black and red are line; white is neutral; green is ground)
- Disconnect the cold inlet and hot outlet at the tank connections (flex hoses unscrew at the tank; rigid pipe requires unsweating or cutting)
- Slide the old tank out, set the new tank in place
- Set the new tank on a drain pan (required in most jurisdictions) and verify it's level
- Connect cold inlet and hot outlet — use flex hoses with new washers, hand-tight + 1/4 turn
- Connect electrical — pull the wires through the conduit into the junction box, connect black-red-white-ground following the unit's wiring diagram
- Install a new T&P discharge tube — must route downward, terminate within 6" of floor or to a floor drain
- Open the cold-water inlet and let the tank fill. Open a hot-water faucet in the house to vent air; close when water flows steadily.
- Verify no leaks at any connection
- Restore power at the breaker — only after the tank is full
- Schedule the inspection through the permit office
Gas tank install — additional steps
Same general procedure as electric, with the gas-specific additions:
- Shut off the gas supply at the main valve or unit valve. Wait 10 minutes for residual gas to clear.
- Disconnect the gas line at the unit. Apply leak-detection solution to any joint you didn't loosen to verify integrity before reuse.
- Disconnect the flue or vent at the tank top. For atmospheric units, the B-vent slides off; for power-vent, disconnect the PVC at the unit.
- After the new tank is set, install a new flex gas connector (never reuse) with yellow gas-rated tape on the threads
- Reconnect the flue or vent — atmospheric must slope upward at minimum 1/4" per foot
- Open gas supply, leak-test every joint with bubble solution — bubbles indicate a leak; tighten and retest
- Light the pilot per the unit's lighting instructions (see our pilot lighting page)
- Verify the burner fires when the thermostat calls for heat
- Schedule the inspection
Tankless install — pro recommended
Tankless installs typically require: gas-line resizing (1/2" to 3/4" — often involves new piping), PVC venting installation (40–100 ft to outside termination), 120V outlet near the unit, condensate drain. Most of this work is beyond the typical handy homeowner.
If you're committed to DIY, expect 8–16 hours of labor including gas line work and venting. Permit and inspection are mandatory. Several jurisdictions require licensed installer for tankless gas — verify locally.
ProTerra heat pump install — special considerations
- Verify 1,000+ cu ft ambient air at the install location
- Install condensate drain — floor drain or condensate pump for 2–4 gallons per day
- 30-amp 240V dedicated circuit (may require panel upgrade in older homes)
- Verify ceiling clearance — ProTerra is taller than standard electric tanks
For more on ProTerra-specific install, see our ProTerra line hub.
Common installation mistakes
- Powering up an electric unit before filling: destroys the elements in seconds
- Skipping the drain pan: code violation in most jurisdictions; leak insurance void
- Reusing the gas connector: aged connectors are a leading cause of post-install gas leaks. New connector every time.
- Not installing an expansion tank on closed-system plumbing: T&P will weep continuously without expansion tank in homes with backflow preventers
- Wrong T&P discharge routing: must terminate downward within 6" of floor or to a drain — capping or up-routing is a code violation and a safety hazard
When to call a pro instead
- Gas line resizing or rerouting
- New venting installation (tankless or power-vent)
- Electrical panel upgrade (typical with ProTerra installs)
- Any sealed-combustion direct-vent install
- If your jurisdiction requires licensed installer
Bottom line
Standard like-for-like electric tank replacement: $400–$700 in pro labor, ~$200 in DIY tools/permits. Standard gas tank replacement: $700–$1,200 pro / $300 DIY. Tankless and ProTerra: pro recommended. For specific Rheem models see our Rheem lineup.