Food service and pool heaters. Gas rules for the places where grease and water live. Episode twenty-six.

Commercial kitchens run floor-mounted ranges, fryers, and griddles — all listed food service equipment. Listed floor-mounted appliances keep at least six inches to combustible material, with two inches at a draft hood. Above the cooking top, unshielded combustibles need eighteen inches for the first two feet. Counter appliances add a vertical rule: at least forty-eight inches between the top of hot plates and griddles and any combustible material above. And every floor-mounted unit sits level, on a firm foundation, with clearances per its listing.

Commercial cooking lives under an exhaust hood. The code requires means to ventilate the space so the gas can burn properly, and the mechanical code governs the hood itself. The key concept is the interlock: exhaust airflow is proven or interlocked so the burners never run without exhaust, and combustion products and grease-laden vapor never pour into the kitchen.

Movable appliances change the connection rules. Appliances on casters must be listed for that construction, and installed so their movement is limited — the connector must never take the strain. A listed quick-disconnect device shuts off gas automatically the moment it is unplugged, and indoor installations still get a manual shutoff valve upstream. Watch the restraint cable go taut before the connector ever tightens.

Grease is relentless. It coats connectors, valves, and everything near the fryers, and it hardens where you least want it. Keep gas connectors, shutoff valves, and appliance controls protected from grease accumulation, and clean around them without flooding gas components with water or degreaser. A connector buried in baked-on grease cannot be inspected — or trusted.

Outside, the pool heater has its own rules. Units are listed as gas-fired pool heaters, located or protected so people do not contact hot surfaces, and installed per the manufacturer. Clearances cannot interfere with combustion air, a hood or vent terminal clearance and relief, or access for servicing. A heater listed for outdoor installation uses the venting means the manufacturer supplies. And chlorine-laden air is corrosive — store pool chemicals away from the heater, because a heat exchanger breathing chlorine dies young.

Water-side protection matters as much as gas-side. If anything downstream can restrict flow from a heater with only over-temperature protection, a pressure relief valve goes in the heater or ahead of the restriction. Without an integral bypass, a bypass line and valve balance the flow. Flow is proven before fire, and winterizing follows the manufacturer — not guesswork.

So walk the kitchen and the pool deck the same way. Verify clearances against the listing — including forty-eight inches over the griddle. Confirm the hood runs and the interlock proves exhaust before fire. Check the quick-disconnect and the restraint cable. And at the pool heater: venting per the manufacturer, and chemicals stored well away.

Six and forty-eight in the kitchen, restraint on the rollers, listed heat at the pool. Grease and chlorine never sleep — inspect like it. Next time: how the code itself is organized.