Commercial Water Heater & Boiler Repair

Not a job for the average plumber

A commercial water heater is a different machine from the tank in a garage. A 100-gallon gas unit firing at 199,000 BTUs or more, or a large three-phase electric heater in a warehouse, has its own controls, venting, power supply and gas supply. When it fails, someone has to test it and find the cause, not swap parts and hope. Our factory-authorized A.O. Smith technicians carry the meters and know what the readings mean. From our shop in Montclair, we serve businesses across Ontario, Rancho Cucamonga, Upland, Chino, Fontana, Pomona and nearby cities.

Hot water boilers

In the trade, a big water heater is often called a boiler. If your building has a boiler that makes hot water for sinks, showers, kitchens or laundry, that is exactly what we work on: hot water supply boilers, the storage tanks, pumps and controls that go with them, and large commercial water heaters. Many run at well over 200,000 BTUs per hour, and some heat the water in the boiler and store it in a separate tank.

Common boiler problems we fix:

No hot water, or not enough during busy hours
Burner lockouts and error codes
Leaking heat exchangers, tanks and fittings
Banging or rumbling from scale buildup
Failed circulating pumps
Relief valves that drip or discharge

See more water heater and boiler problems and their causes.

We work on boilers that make hot water. We don’t service boilers used only for space heating, such as radiators or hydronic heat.

What we test, diagnose and repair

Three-phase electric water heaters: voltage and amperage readings on every leg at 208, 240 and 480 volts, plus heating elements, contactors, fuses and controls. One dead leg or burned element can quietly cut your hot water capacity.
Gas pressure: we measure supply pressure with the heater off and firing, and manifold pressure at the burner, with a manometer. Low pressure under load from an undersized gas line or a failing regulator is a common cause of lockouts and weak hot water on high-input units.
Blower motors and power venting: blowers, pressure switches, venting and condensate drains on power-vent and high-efficiency condensing units.
Ignition and controls: igniters, flame sensors, gas valves, control boards and error codes.
Recirculation and mixing valves: recirculation pumps that keep hot water at the far end of a hotel hallway or school wing, and thermostatic mixing valves that let you store water hot and deliver it at a safe temperature.
Large storage tanks: leaks, sediment buildup, anode rods and relief valves.

Buildings we serve

Building	What usually matters most
Warehouses and industrial buildings	Three-phase electric heaters, correct voltage and balanced elements
Schools	Kitchens, locker rooms and restrooms; work scheduled around class hours
Hotels and motels	Peak morning demand, recirculation loops, hot water on every floor
Restaurants and commercial kitchens	High-temperature water for dishwashing and steady supply during service
Apartment and multi-unit buildings	Central systems that serve many units at once, with tenants waiting

Replacement and new installation

We size a commercial system by peak demand: the fixtures, kitchen equipment, laundry and number of people using hot water at the same time, not by copying the old unit. We install high-efficiency condensing gas, standard gas and three-phase electric water heaters and hot water boilers, including A.O. Smith commercial models, and we check the gas supply, electrical service and venting before we recommend one. We schedule the work around your hours so your building is without hot water for as little time as possible.

Keep it running

Large water heaters last longer and fail less when someone checks them on a schedule: flushing sediment, checking anode rods, testing relief valves, and checking elements or combustion. Ask us about regular maintenance for your building.

When it's down, text us

Text a photo of the rating plate. It shows the model, serial number and the BTU input or voltage and phase. Tell us what the building is and what's happening, and a real person texts you back.

Looking for a home water heater instead? See tank, tankless and heat pump water heaters.

More help with commercial water heaters

Commercial water heater service near you:

Questions we hear a lot

Do you repair boilers?

Yes, boilers that make hot water: hot water supply boilers and large commercial water heaters for sinks, showers, kitchens and laundry. We don't service boilers used only for space heating, such as radiators or hydronic heat.

What's the difference between a boiler and a water heater?

In everyday talk, many people call any large water heater a boiler. A hot water supply boiler is a high-input heater that is often paired with a separate storage tank, while a commercial water heater heats and stores water in one tank. We repair and install both.

Do you work on three-phase electric water heaters?

Yes. We test voltage and amperage on each leg at 208, 240 and 480 volts and repair or replace elements, contactors, fuses and controls on three-phase commercial electric water heaters.

Why does my commercial gas water heater keep locking out?

Common causes are low gas pressure when the burner fires, a blocked vent or failed blower or pressure switch, a dirty flame sensor, or a blocked condensate drain on condensing units. We measure gas pressure and test each part to find the actual cause.

What temperature should a commercial water heater be set to?

Many facilities store hot water at 140°F or higher to limit Legionella growth, then use thermostatic mixing valves to deliver about 120°F at hand sinks and showers. Commercial dishwashing usually needs hotter water, often from a booster heater.

Do you service brands other than A.O. Smith?

Yes. We are a factory-authorized A.O. Smith contractor, and we also service State, Bradford White, Rheem, Lochinvar and other commercial brands.

Can you work after hours?

Yes. We are open 24 hours a day, 7 days a week, and we schedule replacements around your business or school hours whenever we can.