What’s involvedWater heater

Descale a tankless water heater: what's involved

What flushing scale out of a tankless heater takes, the signs it needs it, and what a plumber does. No hands-on steps.

What’s involved

No hands-on steps here: what the job is, what a pro does, and what to have ready.

Minerals in the water coat the heater's insides. Flushing them out keeps the water hot and the heater from shutting itself down.
Under the heater, beside the hot and cold pipes, are two small valves with caps. That's where a plumber connects.
They turn its power and water off, pump a descaler through it from a bucket for a while, flush it with clean water and clean its inlet screen.
Don't open its cover or work its valves yourself.
Water that goes hot then cold, takes longer to get hot, or a scale warning on its screen.
Photograph the heater's label for its model, clear the space under it, and clear a nearby sink or floor drain.
Its power and gas are turned off and its pipes opened while it's done, so it's a plumber's job. Ask Handyman for one.

Handyman says: I'll find a plumber to flush it.

Free for every home. Handyman asks a few questions, then books a pro it trusts.