Replace a Water Heater

advancedHome Repaircheck locally10 steps

Safety Warnings

Wrench — check locally

Spirit level — check locally

Mallet or hammer — check locally

Gouge or chisel — check locally

Water back/boiler — check locally(1)

Muriatic acid — check locally(as needed)

String packing or candle wicking — check locally(as needed)

Shut off the water supply to the unit.

Disconnect all pipes at the unions or joints nearest the fire box.

Loosen and remove any clamps holding the fire-brick lining against the oven, then remove side and end linings.

Lift out the water back and move it to the ground for removal.

Remove soft scale or sludge by pounding the water back with a mallet or hammer.

Tip: Use a long gouge or chisel on reachable surfaces.

If necessary, use muriatic acid to dissolve deposits; let sit for one to two hours.

Tip: Heating the water back hastens the action of the acid.

Pour out the acid solution and flush the unit thoroughly with hot water.

Tip: Ensure acid is completely washed out before proceeding.

Position the new or cleaned water back into the unit.

Tip: Use a spirit level to ensure the water back is perfectly level.

Reconnect pipes to the water back.

Tip: Wrap string packing or candle wicking around the thread just before the joint closes to make it water-tight.

Reinstall the fire-brick linings and secure the clamps.

If the unit is for a whole house with multiple floors, a high-pressure system modification may be required.

Synthesized from 5 verified sources:

Gutenberg: Dwelling ConstructionView →

Gutenberg: Simple Plumbing Repairs (FB 1460)View →

USDA Farmers' Bulletin (Gutenberg)View →

Gutenberg: Electricity for the 4-H ScientistView →

Gutenberg: Electrical GuideView →