Gas Valves for Hot Water Pressure Washer Burners

A gas valve that will not open leaves your hot water machine washing cold, and cold water doubles your time on every job. Sun Brite Supply carries White-Rodgers and Honeywell gas valves, millivolt pilot generators, and ignition modules for natural gas and LP fired burners. Bring the old valve to our Gaithersburg counter or call 301-519-9274 with the model number and we will match it.

Millivolt, 24 Volt, or Electronic Ignition

Burner gas valves come in three control styles, and they do not interchange. A millivolt valve runs on the heat of its own standing pilot. The pilot flame warms a pilot generator that produces roughly 750 millivolts, just enough current to hold the valve's electromagnet open. No transformer, no outside power. That is why millivolt systems show up on skid burners and older hot water machines that work far from an outlet. A 24 volt valve needs a transformer and a control circuit, usually switched by a thermostat or a flow switch. Electronic ignition systems skip the standing pilot entirely. A module such as the Honeywell S8610 sparks the pilot only when the burner calls for heat, proves the flame, then opens the main valve. They burn less fuel sitting idle and relight themselves after wind or a pressure drop blows the pilot out.

The pilot generator does the heavy lifting

On a millivolt system, the valve is only as good as the generator feeding it. A tired generator makes 300 millivolts instead of 750, and the main valve drops out even though the pilot looks healthy. Before you condemn a valve, put a multimeter on the generator leads with the pilot lit. A reading of 500 to 750 millivolts means the generator is fine. Much below 350 and a new generator will fix the burner for about a quarter of the cost of a valve. That is the single most common misdiagnosis we see at the counter.

Matching a Replacement Gas Valve

Four things have to line up. First, fuel type. Natural gas valves regulate outlet pressure near 3.5 inches water column while LP runs near 10 to 11, so the regulator spring and orifice sizing are different. Never move a valve between fuels without the maker's conversion kit. Second, pipe size. Most burner valves use 1/2 inch or 3/4 inch NPT inlets and outlets, and an adapter in the wrong spot can choke flow to a big burner. Third, capacity. Check that the valve's BTU rating covers your burner, since a 400,000 BTU coil heater will starve on a small furnace valve. Fourth, the control style has to match your wiring. If the old valve has a model tag, read it to us over the phone and we can usually cross it to a direct or universal replacement in a few minutes.

Gas Valve and Ignition Part Lookup

Availability moves fast on burner parts. Call before you drive and we will confirm what is on the shelf.

From the Field

The gas valve is the most replaced part that did not need replacing. When a burner quits, the temptation is to swap the big expensive box, but the real fault is usually a worn generator, a dirty pilot hood, or a thermocouple that quit holding the safety magnet in. That is why we keep generators stocked. They fail far more often than the valves they feed. Two habits worth keeping: soap-test every joint you touched after any gas work and watch for bubbles, never check with a flame. And if a valve body has been underwater or cooked by a runaway burner, replace it. There is no approved repair for a flooded or overheated gas valve.

Related Burner and Hot Water Parts

• Burner parts and burner fuel nozzles
• Hot boxes and hot water skids
• Hot water pressure washers
• Thermal relief valves
• Hot water and steam hoses
• Steam guns and hot water lances
• Local pickup at our Gaithersburg, MD store

Frequently Asked Questions

How does a millivolt gas valve work without electricity?

The standing pilot heats a pilot generator that produces about 750 millivolts. That small current holds the valve's electromagnet open, so the system powers itself as long as the pilot burns.

My pilot is lit but the main burner will not fire. Is the valve bad?

Test before you buy. On a millivolt system, check the generator output with a meter. A reading below about 350 millivolts points to the generator, not the valve. On 24V systems, confirm the transformer and switch circuit first.

Can I use a natural gas valve on propane?

Not as-is. LP runs at nearly three times the outlet pressure of natural gas, so the regulator setting and orifices differ. Use a valve rated for your fuel or the manufacturer's conversion kit.

Why does my pilot keep going out?

The usual suspects are a weak thermocouple, a clogged pilot orifice or hood, or draft blowing across the pilot. Clean the pilot assembly first, then test the thermocouple before touching the valve.

What size gas valve does my burner need?

Match the pipe size, usually 1/2 or 3/4 inch NPT, and confirm the valve's BTU capacity covers your burner rating. Read us the old valve's model number and we will cross it.

Should I install a gas valve myself?

Gas work belongs with a qualified technician who can set outlet pressure and leak-test every joint. A soap solution finds leaks safely. The part is cheap compared to what a leak can cost.