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Relief Valves
Watts is one of the leading manufacturers for relief valves, at competitive prices. For more information on these Watts Relief Valves, click on the individual items.
Bell & Gossett Relief Valves
These Bell & Gossett Relief Valves are ASME Safety Relief Valves which protect fired and unfired hot water vessels against hazardous operating pressures. They are engineered in accordance with Section IV of the ASME boiler and pressure code for heating boilers with capacities certified by the National Board of Boiler and Pressure Vessel Inspectors. These Bell & Gossett Relief Valves offer the highest BTUH ratings available on the market today for valves in their class (790,000 to 5,999,000 BTUH). …
Watts 530C Poppet Style Relief Valves
Watts Series 530C Calibrated Pressure Relief Valves are used in commercial, residential and industrial applications to protect against excessive pressure in systems containing water, oil, or air. This Watts Relief Valve consists of a bronze body construction with NPT threaded male inlet and NPT threaded female (drain) outlet connections, stainless steel spring, brass bonnet, Buna-N disc, and Buna-N O-ring. …
Watts 40XL T&P Relief Valves
Watts Series 40L, 40XL Automatic Reseating Temperature and Pressure Relief Valves are used in commercial water heater applications to provide automatic temperature and pressure protection to hot water supply tanks and hot water heaters. These Watts Relief Valves feature a bronze body with NPT male inlet and NPT female outlet connections, unique thermostat with special thermo-bonded coating, tamper-resistant bonnet screws, automatic reseating feature, and test lever. …
Watts 100XL & 10L T&P Relief Valves
Series 100XL Temperature and Pressure Watts Relief Valves are used in water heater and hot water storage tank applications to provide automatic temperature and pressure protection to hot water supply tanks and hot water heaters up to 100,000 BTU/hr. …
Watts 174A Pressure Relief Valves
Watts Series 174A Boiler Pressure Relief Valves are used in hot water heating and domestic supply boiler applications to protect against excessive pressures on all types of hot water heating supply boiler equipment. It consists of a bronze body construction with NPT threaded female inlet and NPT threaded female outlet (drain) connections, non-metallic disc-to-metal seating, stainless steel spring, and test lever. …
Watts 140 Re-Seating Temp & Pressure Relief Valves
Series 140S, 140X Automatic Reseating Temperature and Pressure Relief Valves are used in commercial water heater applications to provide automatic temperature and pressure protection to domestic hot water supply tanks and hot water heaters. …
Zurn-Wilkins P1000A Relief Valve
Zurn - Wilkins P1000A Pressure relief valves is most commonly use for water heater applications. This model is set at 150psi. …
Watts 374A Pressure Relief Valve
Series 374A Boiler Pressure Relief Valves are used in hot water boiler applications to protect against excessive pressure on all types of hot water heating boiler equipment. It consists of an iron body construction with forged bronze inlet connections, non-metallic disc-to-metal seating, stainless steel spring, and test lever. Series 374A resists corrosive water conditions, sticking and freezing, and prevents water and sediment from being trapped in the seat. It is designed for emergency safety relief and shall not be used as an operating control. Standard Pressure Setting: 30psi (206.9 kPa), Pressure Range: In 5psi (34.5 kPa) increments from 30 to 150psi (2 to 10 bar) with corresponding high ratings at 550,000 BTU/hr. …
Watts 740 Boiler Pressure Relief Valves
Series 740 Boiler Pressure Relief Valves are used in hot water space heating boiler applications to protect against excessive pressure on all types of hot water space heating boiler equipment. They consist of an iron body construction with expanded outlet drain connections for hot water space heating boilers, non-metallic disc-to-metal seating, stainless steel spring, and a test lever. Series 740 offers large discharge capacity, resists corrosive water conditions, resists sticking and freezing, and prevents water and sediment from being trapped in the seat. It is designed for emergency safety relief and shall not be used as an operating control. …
Mcdonnell & Miller 250 Series Relief Valves
The Mcdonnell & Miller 250 Series Relief Valves are used for tanks and hydronic heating systems to protect against over pressure. They range in sizes from 3/4" - 2" and have a maximum operating pressure range from 30 - 125 psig. …
Mcdonnell & Miller 260 Series Relief Valves
The Mcdonnell & Miller 260 Series Relief Valves are used for tanks and hydronic heating systems to protect against over pressure. They come in 1-1/2" NPT and range in maximum operating pressure from 30 - 50 psig. …
Cash Acme T&P Relief Valves
Cash Acme is a world leader in temperature & pressure (T&P) relief valves. Used as a safety device on pressurized water heaters and cylinders, this Cash Acme line includes specialized 1/2" models and high capacity commercial products to 2". …
Watts 1XL & 1L T&P Relief Valves
Series 1XL Temperature and Pressure Watts Relief Valves are used in water heater and hot water storage tank applications to provide automatic temperature and pressure protection to hot water supply tanks and hot water heaters up to 15,000 BTU/hr. …
More About Relief Valves
What is a Relief Valve?
A temperature and pressure (T & P) relief valve is the primary "back-up" safety device that prevents water in a pressurized hot water heater from overheating. A T & P relief valve is a two-in-one safety device, which responds both to excessive temperature and to excessive pressure in a water heater. If a system exceeds its temperature/pressure limit, a water heater or pipe will burst, making the proper installation of a T&P relief valve essential.
How does it work?
A T & P valve responds to excessive temperature by expansion of the thermostat. This lifts the disc off its seat and discharges overheated water. As overheated water exits the tank it is replaced by cool water. This process regulates the water temperature in a hot water heater. Typically, when a valve is relieving water in volume, it is due to excessive temperature.
The valve also responds to excessive pressure by discharging water to prevent further pressure increase. When water is heated in a closed system, it expands and causes an increase in pressure. This is called thermal expansion. When the system is opened, pressure will return to normal, and the relief valve will stop dripping. When a backflow prevention device or check valve is installed on the water service entering a building, a closed system is created. When water is heated, it expands. Because the water has nowhere to go in a closed system, a potentially dangerous situation is created, and a T&P relief valve must be installed. If a T & P valve is dripping, rather than relieving in volume, the valve is prevented from closing tightly. A dripping valve usually indicates either thermal expansion or debris on the seat.
T & P relief valves may be constructed of bronze or cast iron. To select the proper T & P relief valve a system's capacity, pressure, and temperature requirements must be determined. At PexSupply.com, we offer a wide selection of Bell & Gossett, Watts, Zurn - Wilkins, McDonnell & Miller, and Cash - Acme relief valves to protect your heating system.
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