Watts 174A Pressure Relief Valves

Watts 174A pressure relief valves protect boiler equipment against excessive pressure buildup in hot water heating and domestic supply boiler applications. The valve uses a bronze body with NPTF female inlet and outlet connections, an above-drain seat designed to keep sediment from fouling the valve, and a non-mechanical seat-to-disc alignment built to resist sticking or freezing. Pressure settings run in 5 psi increments from 30 to 150 psi, giving a contractor a setting to match nearly any boiler's operating pressure. The valve is rated ASME and built strictly for emergency safety relief, not as an operating control, with an integrated test lever for periodic function checks. Matching the pressure setting to the boiler's actual operating range is the detail that keeps this valve doing its job without nuisance discharge.

Subcategories

• 30 psi Standard Setting Valves: The 30 psi setting is the standard configuration most commonly specified for residential and light commercial hot water heating boilers. It is the baseline pressure rating in the 174A series, with higher settings available in 5 psi increments up to 150 psi for larger or higher-pressure boiler systems. Contractors default to this setting unless the boiler manufacturer specifies a higher operating pressure. The bronze body and NPTF connections stay the same across every pressure setting in the series.
• Higher Pressure Settings (40 to 150 psi): Settings above the 30 psi standard, available in 5 psi increments through 150 psi, cover commercial boiler equipment running at higher operating pressures than a typical residential system. Selecting the correct setting depends entirely on the connected boiler's rated operating pressure rather than a default choice. Getting this wrong in either direction either triggers nuisance relief events or leaves a boiler without adequate overpressure protection. The valve construction, including the bronze body and above-drain seat, stays consistent regardless of the pressure setting chosen.
• Discharge Monitoring Accessories: SentryPlus Alert discharge line flood sensors pair with 174A valves to monitor for unwanted discharge events and can integrate with building automation systems. A facilities team managing several boiler installations benefits from adding these sensors where an undetected relief event would otherwise go unnoticed until water damage shows up. The sensor is an add-on to the valve rather than a required component for basic operation. Pairing monitoring hardware with the relief valve gives an added layer of visibility on commercial installations in particular.

Buying Guide

The pressure setting is the first and most important decision on any 174A order, since the valve needs to match the connected boiler's actual rated operating pressure rather than a generic default. The series covers 30 psi as its standard setting, with higher options available in 5 psi increments up to 150 psi for commercial boiler equipment running at elevated pressures. Watts 174A Pressure Relief Valves are built around a bronze body with NPTF female inlet and outlet connections, so confirming thread type and size against the existing piping is the next check before ordering a replacement. The above-drain seat design and non-mechanical seat-to-disc alignment are built into every setting in the series, so those features do not factor into which specific valve to order, only the pressure rating and connection size do. Every valve in the series carries an ASME rating and is intended strictly for emergency safety relief rather than as an operating control, which matters when explaining the valve's role to a building owner who may expect it to double as a pressure regulator. For installations where an undetected discharge event would be costly, pairing the valve with a SentryPlus Alert discharge line flood sensor adds monitoring that the base valve does not include on its own. Confirming pressure rating, connection type, and whether discharge monitoring is warranted covers the decisions that matter on a 174A order.

Frequently Asked Questions

What pressure settings are available on the Watts 174A?

The series runs from a 30 psi standard setting up to 150 psi, available in 5 psi increments. The correct setting depends on the connected boiler's rated operating pressure.

Can the 174A valve be used as an operating control?

No. The valve is built strictly for emergency safety relief and is not designed or rated to function as an operating pressure control. A separate control device handles normal pressure regulation.

What connection type does the 174A use?

It uses NPTF female threaded connections on both the inlet and outlet, with a bronze body construction across the series. Confirming thread size against the existing piping is necessary before ordering a replacement.

Does the 174A include any way to monitor discharge events?

The base valve does not include monitoring on its own, but SentryPlus Alert discharge line flood sensors can be added to detect unwanted discharge and integrate with building automation systems. That sensor is an optional accessory rather than a built-in feature.

Is the Watts 174A ASME rated?

Yes, every valve in the series carries an ASME rating. It is designed for emergency safety relief on hot water heating and domestic supply boiler equipment.