Several factors could cause hot water not to work after replacing a water heater. Here are some possible reasons:
Power supply: Ensure that the new water heater is properly connected to a power source. Check the circuit breaker or fuse box to make sure the circuit supplying electricity to the water heater is functioning correctly.
Gas supply: If you have a gas water heater, verify that the gas supply is turned on and properly connected. Make sure the pilot light or ignition system is functioning correctly.
Thermostat settings: Check the thermostat settings on the new water heater. It's possible that the temperature is set too low or that the thermostat is not functioning correctly. Adjust the settings as needed.
Air pockets in the system: After installing a new water heater, there may be air pockets in the plumbing system, preventing hot water from flowing properly. Open the hot water faucets throughout the house to allow the air to escape. Alternatively, you can bleed the air out of the system by opening the pressure relief valve on the water heater while the hot water faucets are open.
Incorrect installation: Double-check the installation of the new water heater. Ensure that all connections are secure and properly tightened. Make sure that the water lines are correctly connected, and there are no leaks or blockages.
Pressure relief valve: The pressure relief valve on the water heater may be stuck or faulty. This can result in hot water not being delivered properly. Test the valve by lifting the lever slightly and allowing some water to flow out. If no water comes out or it continues to leak, the valve may need to be replaced.
Dip tube issues: The dip tube inside the water heater carries cold water to the bottom of the tank. If the dip tube is broken or deteriorated, it can affect the distribution of hot water. Check the condition of the dip tube and replace it if necessary.
If you've checked these potential causes and still can't determine the issue, it may be best to contact a professional plumber to diagnose and resolve the problem.