Suburban Mfg 5381A ST-42 Tankless On-Demand LP Gas RV Water Heater 42,000 BTU

The Suburban 5381A ST-42 is a 42,000 BTU LP gas, on-demand tankless water heater engineered for permanent installation in RV appliance bays. Unlike traditional tank-style heaters, this on-demand unit only fires the burners when hot water is actually needed — eliminating standby heat loss and delivering an endless supply of hot water for showers, dishwashing, and more. The compact footprint is designed to fit standard 6-gallon RV water heater openings, making it a straightforward upgrade for most coaches.

The ST-42 delivers continuous hot water up to 120°F at a flow rate of 1.5 GPM (with inlet water temperatures at 70°F or higher) and includes a wall-mount digital On-Demand Control Center for convenient temperature adjustment. Direct Spark Ignition (DSI) provides reliable, automatic lighting without a pilot light. Note: Access door is sold separately.

Safety Features:

• Flame-Out Protection — Immediately cuts gas supply if low propane pressure or a burner malfunction is detected
• Scald Protection — Internal high-temperature kill switch caps outlet water at 131°F to guard against thermostat failure
• Child Lock — Limits maximum outlet temperature to 113°F for households with young children
• Active Freeze Protection — Built-in mechanism helps protect internal components in cold weather conditions
• Automatic Fan Monitoring — Shuts off gas supply if combustion airflow is interrupted
• Pressure Relief Safety Valve — Releases excess pressure to protect the system
• Voltage Protection — Guards internal electronics against power fluctuations

Specifications:

• Fuel Type: LP Gas (Propane)
• BTU Input: 42,000 BTU/hr
• Ignition: Direct Spark Ignition (DSI)
• Flow Rate: Up to 1.5 GPM at 70°F inlet water
• Dimensions: 12-1/2 in. H × 12-3/4 in. W × 13 in. D
• Weight: 19 lbs (without door)
• Installation Type: Non-portable, permanent mount
• Includes: Wall-mount digital On-Demand Control Center
• Access Door: Sold separately

Backed by a 2-year limited manufacturer warranty, the Suburban ST-42 is a trusted choice for RV owners seeking reliable, energy-efficient hot water on the road.