Replace a hot water boiler or heater by removing the old heater, draining it, connecting the pipes and gas or power lines to the new boiler and adding the water supply. The steps are the same for both electric and gas boilers.
Shut off the water supply, gas valves and electricity before disconnecting and removing the old heater. If the gas supply is completely shut off, the pilot light switches off automatically. Position the drain valve of the boiler above the floor drain, attach a hose and open it. Allow the hot water tank to drain completely. Disconnect the utility lines, which includes the hot and cold water pipes, gas lines and electrical wires. Finish by removing the flue. Remove the old hot water heater, and roll the new one in.
Connect the new segments and fitting that come with the new boiler. These include a flex pipe, a temperature and pressure relieve valve and a discharge drain pipe. Wrap the fittings with Teflon tape. Then, connect the water lines, gas or electric line and the flue. Check for any gas or water leaks. Turn on the water, gas and electricity. Allow the water tank to fill completely, and turn a faucet to hot to see if the water warms up.