No hot water? Check these first.

First: gas or electric?

Look at the unit. A vent pipe coming off the top and a gas line into the bottom means gas. No vent and a heavier electrical cable or conduit means electric. Tankless units follow the same rule.

Electric heaters — two quick checks

• The breaker — water heaters are usually on their own double breaker. If it tripped, reset it once. Trips again? An element is failing or wiring has a problem — stop there.
• The reset button — behind the upper access panel (kill the breaker first) is a red button on the thermostat. One press, wait an hour. It trips when water overheats — and it usually trips for a reason.

Gas heaters — pilot and supply

• The pilot light — look through the little sight glass at the bottom. No flame, no hot water. The relighting steps are printed right on the tank label.
• The gas valve — make sure nobody bumped the shutoff on the gas line (happens after other work in the basement).
• Pilot will not stay lit? — that is usually a thermocouple or gas valve. Cheap part, but it is a service call — do not bypass the safety controls.

Lukewarm counts too

Hot for two minutes then cold? That is sediment in the tank or a dead element — see how long water heaters actually last for the full picture. In Bucks and Montgomery County hard-water areas, sediment is the usual suspect.