Watts 174A-045 1 Relief Valve, Bronze, NPT

The Watts 174A-045 1 is a 1" pressure relief valve for hot water boiler service, factory set at 45 psi. It features a bronze body. Rated to 150 psi and up to 250°F.

This 3/4 inch boiler pressure relief valve is 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. It 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, not as an operating control. The pressure relief is set at 45 psi (310.3 kPa). Pressure Range: In 5 psi (34.5 kPa) increments from 30 to 150 psi (2 to 10 bar) with corresponding high ratings from 650,000 to 14,370,000 BTU/hr.

Features

• Bronze body construction
• Standard pressure relief setting 45 psi
• Nonmetallic disc-to-metal seating
• For hot water heating and supply boilers

Common Questions

What pressure is this valve set to?

It is factory set to relieve at 45 psi. The setting is fixed and is not field-adjustable. Note the 150 psi figure in the specifications is the maximum of the series' pressure range — the ceiling the body is built for, not this valve's relief point. This valve opens at 45 psi. Match it to the appliance nameplate: the relief setting must not exceed the working pressure stamped on the vessel you are protecting.

Is this ASME rated?

Yes. It is ASME rated and carries the "HV" code symbol under ASME BPVC Section XIII (the section that replaced Section IV for overpressure protection), and it is National Board (NBBI) certified. Inspectors look for that stamp on the valve body, and it is there.

Can I use this on potable water?

No. This is a boiler valve and is not approved for potable water, and that is true regardless of what the lead-free column says — hydronic boiler water is a closed, treated loop and is not drinking water. For a potable hot water heater or storage tank, use a T&P relief valve listed to ANSI Z21.22 / CSA 4.4 instead.

Does the discharge have to be piped?

Yes. Codes require the outlet to be piped full-size to a safe point of discharge, terminating with an air gap and no valve, cap, or reducer anywhere in the line — a relief valve that cannot discharge freely is not protecting anything. The manual test lever should be operated at least annually to confirm the valve is not seized.

Specifications

• Type: Relief
• Size: 1"
• Inlet Size: 1"
• Outlet Size: 1"
• Connection: NPT
• Body Material: Bronze
• Max Pressure (psi): 150
• Pack Quantity: 12
• Country of Origin: United States
• Warranty: 1 Year Limited
• MPN: 174A-045 1
• Temperature: up to 250°F
• Certifications: ASME Section XIII (HV), NBBI
• Lead-Free: No
• Relief Type: Pressure Only
• Factory Set Pressure (psi): 45
• ASME Code Rating: ASME Section XIII (HV)
• Application: Hot Water Boiler
• Connection Configuration: FNPT inlet x FNPT outlet
• Manual Test Lever: Yes
• Approved for Potable Water: No
• SentryPlus Alert Flood Sensor: No