Replacing a water heater with the same type — tank-to-tank, same fuel source — is a relatively predictable, moderate cost. Switching fuel types (electric to gas) or converting from a tank to a tankless system costs meaningfully more, mainly due to the additional installation work involved, not just the unit itself.
What drives the total cost
| Factor | Effect on cost |
|---|---|
| Tank size (capacity) | Larger tanks cost more, both for the unit and sometimes for stronger structural/venting requirements |
| Fuel type (gas vs electric) | Gas units are often somewhat more to purchase; switching fuel types adds significant installation cost |
| Tank vs tankless | Tankless units cost considerably more upfront and typically require additional venting and gas line work if converting from tank |
| Code/venting updates required | Older installations sometimes need updated venting or connections to meet current code, adding to the job |
| Removal and disposal of the old unit | Usually a modest additional cost bundled into most installation quotes |
Tank replacement vs going tankless
A straightforward tank-to-tank swap using the existing gas line, vent, and electrical connections is the cheapest and fastest option. Converting to a tankless system costs more upfront — often by a significant margin — because it usually requires new venting, a larger gas line (tankless units draw more gas at peak demand), and sometimes electrical work, on top of the unit’s higher purchase price. The trade-off is a tankless system’s compact size, longer typical lifespan, and lower standby energy use, which can offset the higher initial cost over time.
How age factors into the decision
Tank water heaters typically last 10–13 years. A unit already at or past that mark that develops a tank leak (as opposed to a fixable component fault) is generally not worth repairing — a leaking tank itself cannot be patched, only replaced. See our guide on water heater leaking from the bottom for how to tell a tank leak from a fixable connection or valve leak.
Worth checking before you replace
Not every water heater problem means the tank itself has failed. No hot water, lukewarm water, strange noises, or a pilot that will not stay lit are all covered with specific fixes in our water heater troubleshooting guide — many of these are inexpensive component repairs rather than a sign the whole unit needs replacing.
