ESS Tepid Water Heater

Homepage ESS 1024x574 - ESSThe ESS water heater is a packaged system designed to meet the requirements of ANSI Z358.1-2014 for tepid water delivery to an emergency safety shower or drench system. This heavy-duty water heater is constructed of a carbon steel tank and internally lined with 1/2″ thick Hydrastone cement to ensure tank longevity when operating at elevated temperatures. It is fully insulated with 3″ thick polyurethane foam to minimize standby heat loss.

This tepid water heater has a mixing valve designed, tested, and proven for use in emergency safety shower/face/eyewash applications. The entire package, including the mixing valve, is factory piped and mounted to the water heater to provide single-source responsibility.

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Design Features:

The ESS Tepid Water Heater is designed to meet your emergency drench system needs by incorporating the following critical features:

  1. The carbon steel tank is internally lined with specially formulated hydrastone cement and does not require anodic protection. This lining is critical to the tank’s longevity when storing hot water at elevated temperatures.
  2. The Therm-O-Mix®/WWM thermostatic mixing valve is designed for emergency safety drench systems. It is factory piped and packaged with the water heater tank to simplify installation and ensure a safe and dependable system.
  3. The ESS has 3″ foam insulation which reduces standby heat losses by over 24% compared to 2″ insulated tanks.
  4. Unlike instantaneous heaters, the ESS’s ability to provide tepid water is unaffected by the loss of electric power. Furthermore, the dial temperature gauge provides the operator with positive visual verification that the unit is at temperature.

Example Installation:

Model EMV Piping Illustration e1614187308726 - ESS

NOTE: For two-shower operation, the minimum water pressure needs to be 60 PSIG to satisfy the ANSI Z358.1 pressure spec of 30 PSIG at the shower head. If longer than 20ft runs from the heater to the shower station are needed, the water pressure needs to be 68 PSIG for up to 50ft and 81 PSIG for up to 100ft.



  • Instant and continuous tepid water delivery to an emergency safety shower or face/eyewash station
  • Thermostatic mixing valve designed specifically for emergency drench systems ensures a constant flow of tepid water
  • Self-actuating mixing valve prohibits the delivery of overheated water to prevent scalding even when an accident causes a loss of electric power
  • Reduces the risk of Legionella because water is stored at an elevated temperature
  • Compliant with OSHA and ANSI tepid water standards
  • Full five (5) year non-pro-rated tank warranty



  • Heavy duty carbon steel tank
  • Internally lined with 1/2″ thick Hydrastone cement to ensure tank longevity when operating at elevated temperatures
  • Fully insulated with 3″ thick polyurethane foam to minimize standby heat loss
  • Packaged System includes Therm-O-Mix®/WWM, all electrical operating controls, and a dial gauge
  • The pressure sensing controller with a valve actuator on the Therm-O-Mix®/WWM includes a safety override feature that continuously senses the final mixed water temperature to keep the final water temperature from overheating
  • Each valve is performance tested at the factory to ensure proper operation

Safety Features:

TOM WWM 177x300 - ESS

The Therm-O-Mix®/WWM mixing valve is equipped with advanced features to ensure optimal water temperature and pressure control. This valve integrates a pressure-sensing controller alongside a thermal actuator, which monitors the water pressure from both hot and cold-water inlet connections. If there is a lack of hot water pressure, the actuator overrides the mixing valve to allow cold water flow. Similarly, if cold water pressure is absent at the mixing valve inlet, the valve ensures safety by closing the hot water port to prevent the release of overheated water.

The valve also includes a safety override feature that continually monitors the final mixed water temperature. In the event of overheating, the valve automatically closes the hot water port and fully opens the cold water port to maintain safe water temperatures. Importantly, even in fault conditions, the Emergency Safety Shut-off (ESS) feature ensures compliance with ANSI standards, providing a continuous flow of water with no additional pressure drop.

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