Tankless Water Heater in San Diego, CA

How it works

A tankless unit heats water only when a hot tap opens, passing it through a heat exchanger instead of keeping a tank hot all day. That frees up floor space and avoids standby heat loss. The tradeoff is a limit on flow: each model can only heat so many gallons per minute, so it has to be sized for the showers and appliances you run at the same time.

Scale is the main enemy here

The City of San Diego reports average hardness of about 13.8 to 14.2 grains per gallon for water from its three treatment plants. In a tankless unit, minerals coat the narrow passages of the heat exchanger, cutting flow and output and triggering error codes. Most manufacturers call for periodic flushing with a descaling solution through the service valves. A softener or scale-control system in front of the heater reduces how often that is needed. Ask the plumber to install isolation valves if the unit does not have them.

What an installation involves

• Gas supply. Gas tankless heaters draw far more fuel at full fire than most tanks, so the existing gas line often needs to be upsized.
• Venting. Units need their own vent type and route, or an exterior mount.
• Electric models. Whole-house electric units can require a large amount of electrical capacity, so a panel check comes first.
• Condensate. High-efficiency gas models produce acidic condensate that needs a drain.

Permits in the City of San Diego

The City's Simple No-Plan permit covers water heater replacement on non-historic homes, but it specifically excludes tankless units. A tankless install goes through a Plan permit with Development Services, which also applies to historic properties. Because gas, venting and electrical work are often involved, a careful plumber will plan for that review from the start.

Outdoor units near the coast

Mild weather lets many San Diego homes mount tankless heaters on an outside wall. Close to the beach, salt air can corrode cabinets and fittings, so check exterior units for rust and keep the vents clear. Freezes are rare at the coast but can happen in inland valleys and higher areas, and most units rely on power to run their freeze protection.

Cost factors

• Gas line upsizing or electrical upgrades
• New venting and condensate drainage
• Indoor versus outdoor mounting
• Permit and plan review
• Scale treatment added at install