THE SHORT VERSION
- Confirm what's included, permits, removal and timing in writing.
- Clear the route and the space around the heater.
- If you smell gas, leave first and call from a safe place.
Before you book
- The full written price, including labor, permits and removal of the old unit
- Who pulls permits and schedules the inspection
- Whether any gas or electrical work is subcontracted
- How long you’ll be without hot water
How long it takes
Rheem says most standard replacements take a few hours, while complex installations can take longer. ENERGY STAR notes heat pump installs may need time to order the right model and take longer than a standard swap.
Prepare the space
Clear stored items from around the heater and along the route from the door. Code requires the heater to be accessible for service and replacement, and installers need room to work safely. Photos of the existing heater and space help installers prepare; some quote from them.
Know what you have
ENERGY STAR notes that a 3–4 inch round flue coming out of the top usually means a gas (or propane) water heater. The label on the tank lists the model, capacity and fuel.
After the install
Keep the model and serial numbers, invoice, permit record and warranty registration together. Ask how to flush the tank or descale a tankless unit, and how often. An electric tank should be full before power is turned on; dry-firing burns out the elements.
If you smell gas
Leave the area right away and avoid anything that could spark, including light switches and phones, until you’re at a safe distance. Then call your gas utility’s emergency line or 911. Follow your own utility’s instructions.
Sources
Sources checked September 29, 2026. Prices, codes and rebates change. Check current details with your installer and local permit office.