Pressure Washer Switches

A ten dollar switch takes down more hot water machines than any burner part we sell. This collection covers pressure switches, flow switches, vacuum switches, high limit switches, and the 12V rockers and toggles that run hose reels and burners. Chasing a burner that will not fire? Call 301-519-9274 and we will help you test the circuit before you spend a dollar on parts.

How a Pressure Switch Controls Your Burner

Every hot water pressure washer needs proof that water is moving before the burner lights. If the flame runs while the gun is closed, the water sitting in the coil cooks in seconds, and now you are pricing a new coil instead of a switch. Manufacturers handle this three ways, and knowing which one your machine uses is half the diagnosis.

A pressure switch reads pump discharge pressure and closes the burner circuit when it sees roughly 500 to 700 PSI. Pull the trigger, pressure builds, burner fires. Release it and the circuit opens. These are the standard on most gas engine hot water skids because they are simple and tough. A flow switch does the same job a different way. A magnetic piston or paddle inside the housing lifts when water actually moves through the line, usually at a gallon or two per minute, and that closes the contacts. Flow switches are the better call on machines fed by a float tank, where discharge pressure can stay up even when flow stops. A vacuum switch reads suction on the pump inlet instead, ours trips at 4 inches of mercury, and belt drive machines with long inlet runs often use them.

High Limit Switches: The Last Line of Defense

The high limit switch screws into the coil outlet plumbing and opens the burner circuit if outlet temperature climbs past its rating. We carry them in 176, 210, and 230 degree ratings with 1/2" MPT threads. Match the rating your machine builder specified. Put a 230 degree switch on a machine designed for a 176 and the burner keeps firing well past safe temperature. A high limit that trips on every job is not a bad switch, it is telling you the burner is over-firing, the flow is restricted, or the thermostat has failed closed. Fix the cause, not the messenger.

12V Switches for Reels and Soft Wash Rigs

The other half of this collection is low voltage. Electric hose reels, 12V burners, and soft wash pump boxes all need a rocker or toggle rated for the amp draw. A bare toggle works, but on an open trailer a rubber toggle boot keeps road spray out of the contacts and doubles the life of the switch. Reel motors pull hard on startup, which is why Hannay runs a solenoid between the switch and the motor. If your reel clicks but will not spin, test the solenoid before you condemn the motor.

Switch Lookup by Job

Prices move and stock rotates. Call before you drive if you need one today.

From the Field

The most expensive mistake we see is throwing burner parts at a switch problem. A no-fire complaint walks in, and the customer has already replaced the fuel nozzle, the ignitor, and sometimes the fuel pump. Then we jumper the pressure switch for a five second test and the burner lights right up. Test the cheap stuff first. Pull the leads off the switch, set a meter to continuity, and pull the trigger. No click and no continuity with the gun open means you found it. And the fact that we sell the pilot valve assembly for General Pump flow switches separately tells you something: the internals wear out from debris long before the body does. If your machine keeps eating flow switches, the real fix is usually a filter upstream.

Related Collections

• Burner parts for the rest of the fire side
• Thermostats to set your target temperature
• Ignitors and transformers
• Fuel nozzles and gas valves
• Electrical components and ground fault cords
• Hose reels that pair with 12V switches
• Hot water pressure washers
• Local? Stop by our Gaithersburg pressure washer store

Frequently Asked Questions

What does a pressure switch do on a hot water pressure washer?

It closes the burner circuit when pump pressure climbs past roughly 500 to 700 PSI, which only happens when the trigger is pulled. That keeps the burner from firing into a dead-headed coil and boiling the water inside it.

What is the difference between a pressure switch and a flow switch?

A pressure switch reacts to discharge pressure, a flow switch reacts to actual water movement. Flow switches are the safer pick on float tank machines, where the line can hold pressure even after flow stops.

Why does my burner not fire when I pull the trigger?

Check the switch chain first. Jumper the pressure or flow switch for a few seconds. If the burner lights, replace the switch. If it still will not light, move on to the thermostat, high limit, fuel, and ignition. Most no-fire calls we take end at the switch.

What temperature high limit switch do I need?

Match what your machine builder installed, usually stamped on the old switch. We stock 176, 210, and 230 degree versions in 1/2" MPT. Never install a higher rating to stop nuisance trips, because those trips are warning you about a real overheat problem.

What is a vacuum switch on a pressure washer?

It senses suction on the pump inlet, ours at 4 inches of mercury, and closes the burner circuit when the pump is actually drawing water. Some belt drive and tank-fed machines use them instead of pressure switches.

Can I bypass a burner switch permanently?

No. A jumper is a five second diagnostic, not a repair. Running a burner with the safety chain bypassed can overheat the coil, blow a rupture disc, or worse. The replacement switch costs less than any of those outcomes.

Do you carry 12V switches for hose reels and soft wash systems?

Yes. Toggles, rockers, boots, and Hannay reel solenoids. Call 301-519-9274 with your amp draw and we will match a switch that will not melt under load.