How a Repair Call Works
The purpose of a repair visit is to find out what actually failed, which is not the same as selling you a new water heater. Plenty of units that look finished need a $200 part. Here is the sequence a proper diagnosis follows.
1. Confirm the Symptom
No hot water, not enough hot water, and water that will not stay hot are three different faults with three different causes. The plumber starts by reproducing what you are seeing.
2. Test the Components
On an electric unit that means checking both thermostats and both heating elements. On gas it means the thermocouple, gas control valve, burner assembly, and venting. Testing takes minutes and eliminates guesswork.
3. Check the Tank Itself
If the tank has corroded through, no repair will save it, and you should be told that plainly rather than sold a part that buys a few weeks. Rust in the hot water and moisture at the base are the tells.
4. Repair or Give You the Math
If it is a component, it gets replaced and tested. If the tank is finished, you get the repair cost and the replacement cost side by side so the decision is yours.
If replacement turns out to be the right call, see water heater installation or tankless water heaters. See water heater repair costs.