The hood gas valve is an automatic shutoff the fire code requires on the gas feeding cooking equipment under a hood. It closes when the fire suppression system goes off and, on electric valves, when building power drops or the hood panel shows certain faults. It stays shut until someone resets it by hand.
Why does the fire code require it?
Because a grease fire needs to lose its fuel. Phoenix's fire code, Section 904.14.2, says "The actuation of the fire-extinguishing system shall automatically shut down the fuel and electrical power supply to the cooking equipment. The fuel and electrical supply reset shall be manual." Gas appliances lose their gas through the valve. Electric appliances under the hood lose power through a shunt trip breaker or a relay.
The manual reset rule is deliberate. It forces someone to look at the kitchen before gas flows back to a line of open burners.
How does the electric gas valve work?
It's normally closed and held open by power. CaptiveAire's manual for its CORE fire system describes it: "The electric gas valve is held open in the energized state and closes when de-energized via the output relay of the control panel. A listed manual reset relay is required to ensure manual reset prior to fuel being restored in accordance with NFPA17A." The panel has a reset input for a push button, which is the button kitchen staff usually find on or near the hood controls.
The same manual adds two installation details a plumber sees on the gas side: electric gas valves "must be installed with an upstream strainer to prevent debris from prohibiting gas valve function," and gas has to flow in the direction marked on the valve and strainer.
What makes the valve close?
The usual triggers, from the most serious to the most common:
| Trigger | What happened | What comes next |
|---|---|---|
| Suppression system discharge | Heat detection or a fusible link fired the system, and agent sprayed the hood and appliances | Clean up, then the fire suppression contractor services the system before cooking |
| Manual pull station | Someone pulled the handle near the kitchen exit. Section 904.14.1 places it 10 to 20 feet from the hood | Same as a discharge |
| Building power loss | CaptiveAire: "all 120V AC gas valves/electrical appliances will shut down immediately" when building power fails; 24V DC valves stay open a few minutes on battery | Reset after power returns, following the steps below |
| Panel faults | CaptiveAire lists faults that "will shut down Gas/Shunt," and says cooking shuts down if a supervised loop fault lasts 24 hours | Fire suppression contractor finds the fault |
| Test mode left on | "If the system is left in test mode for 15 minutes, the gas valve will be locked out until test mode is deactivated" | Service tech ends test mode |
Other brands have their own fault lists and reset steps, so keep your system's manual where the kitchen manager can find it.
How do you get the gas back on safely?
First, figure out why it closed. If the suppression system discharged or the pull station was used, don't reset it yourself. Phoenix's fire code, Section 904.14.5.2, requires the system to be serviced "after activation of the system," by qualified individuals, with a certificate sent to the fire code official. Call your fire suppression company.
If the valve closed from a power outage and the system did not discharge, the reset typically goes like this:
- 1Turn every appliance valve and burner knob off on the cooking line.
- 2Make sure the hood fans and controls are back on with no faults showing on the panel.
- 3Press the gas reset on the hood control panel.
- 4Relight pilots one appliance at a time, following each appliance's instructions. CaptiveAire's hood manual warns: "System may require a GAS reset and relighting of all pilot lights. Do not enable GAS without lighting all pilot lights."
- 5Stop if you smell gas. Don't touch switches, burner knobs or other controls. Get everyone out, then call 911 and Southwest Gas at 877-860-6020 from a safe place.
The fuel gas code has a matching rule for any system restored after an interruption: Section 406.6.3 requires a leak check right after gas is turned back on, and 406.6.4 says appliances aren't placed in operation until connections have been checked. On a simple power-outage reset, staff relighting pilots per the manufacturer's steps is normal. After any repair, piping change or discharge cleanup that disturbed connectors, have the connections checked before cooking.
### What if it won't reset, or keeps closing?
Then something upstream is still telling it to close, or the valve itself has a problem. Common reasons:
- A fault is still active on the hood or fire panel. The panel's fault code or light points to it.
- No power at the valve, from a tripped breaker or wiring problem.
- A valve problem. If power and the panel check out, the valve itself may need service.
The opposite problem is a safety issue: a valve that doesn't close when it should may not cut the gas in a fire. CaptiveAire's troubleshooting chart lists it as "Gas Valve does not Close," caused by "Debris on gas valve seal," and the fix is to "Fully clean gas valve and strainer." That's a job for a qualified tech with the gas shut off, and the reason the manual calls for a strainer upstream.
### Can hood cleaning trip it?
It can, if the controls get wet or powered back up in the wrong order. CaptiveAire's hood manual gives cleaning crews two rules that protect the gas valve's controls. First: "Do not pressure wash hood controls, fire systems, or electrical cabinets." Second, when cleaning is done, turn the fan disconnect switches back on first, then the hood control panel breaker, and confirm no error messages show on the panel. Only then reset the gas and relight the pilots. If the gas stays off after a hood cleaning, check the panel for a fault before calling anyone, and tell the cleaning company what you see.
Who fixes which part?
Three trades touch this one valve, and calling the right one first saves a day:
- Fire suppression contractor: the suppression system, detection, pull station, fire panel faults, service after discharge, and the certificate. HQ doesn't do this work.
- Electrician: power to the hood panel and valve, shunt trip breakers and wiring.
- Licensed plumber: the gas piping around the valve, including leaks, low gas pressure, strainers, and piping changes when the cooking line is rearranged.
Never bypass or jumper the valve to keep cooking. Section 904.14.2 requires the automatic shutoff, and a bypassed valve means a hood fire keeps its fuel.
HQ Plumbing & Air handles the gas piping side for restaurants across the Phoenix area: commercial gas line repairs, gas pressure problems, and piping for new or moved cooking equipment, with 24/7 emergency service. For a gas smell in the kitchen, our page on a gas smell in a restaurant covers the first steps, and our guide to whether a restaurant needs a gas leak inspection explains how the fire code's hood checks fit with the gas code.
Know why it closed before you reset it. That's the rule.