Watts N55B-M1 and LFN55B-M1 Water Pressure Reducing Valve

Product Overview

This document provides instructions for the installation, maintenance, and adjustment of the Watts N55B-M1 and LFN55B-M1 Water Pressure Reducing Valves. These valves are designed to reduce high incoming water pressure to a lower, safe, and usable pressure for plumbing systems.

The valves are available in various sizes, including 1/2" to 1 1/2" (15-25mm).

Installation Instructions

1. The valve should be installed by a licensed contractor in accordance with local codes and ordinances.
2. Install the valve in an accessible location with sufficient clearance for cleaning, service, or adjustment.
3. Ensure pipe ends are reamed and threads are cut to size. For valves with Quick-Connect tailpieces, refer to the “Quick-Connect Installation” instructions.
4. Flush the lines to remove all loose scale, dirt, and other foreign matter before installing the valve.
5. Install the regulator with the arrow on the body pointing in the direction of water flow.
6. The regulator can be installed vertically or horizontally (upright or inverted).
7. Start-up: Open the cold water supply, then the hot water supply. Inspect for leaks.

Note: The valve should be inspected annually to ensure maximum life and performance. The N55B-M1 or LFN55B-M1 Valves are suitable for accessible outdoor or pit installations.

Quick-Connect Installation

To Connect:

1. Mark the pipe at the correct insertion depth.
2. Clean the pipe end.
3. If using PEX tubing, insert the pipe stiffener (provided) into the end of the pipe.
4. Push the tubing into the tailpiece up to the mark.
5. Insert the collet clip.

To Disconnect:

1. Remove the collet clip.
2. Depress the collet.
3. Pull the tubing from the tailpiece.

Maintenance Instructions

• To clean the strainer or replace the seat/stem module, shut off the supply, loosen the Locknut and Lock Seal, and back off the Adjusting Screw.
• Remove the Spring Cage, Spring, Washer, and Slip Ring. Grasp the Stem Nut with fingers or pliers and lift the module from the body.
• Replace the module and reassemble the valve.
• Readjust the pressure setting.

Adjustment

The regulator is factory preset to 50psi (344 kPa). To adjust the pressure setting:

1. Loosen the lock nut.
2. Turn the adjusting bolt clockwise to increase pressure, or counter-clockwise to decrease pressure.

CAUTION: When adjusting the reducing valve, use a pressure gauge to verify the correct pressure setting. Do not bottom out the adjusting screw on the spring cage.

Bypass Feature

This regulator has a built-in thermal expansion bypass feature. This feature prevents downstream pressure from rising more than 10psi above the supply pressure.

Note: The bypass feature will not prevent the pressure relief valve from opening on the hot water supply system with pressures above 150psi (10.3 bar).

Troubleshooting

High System Pressure

If the downstream system pressure is higher than the set pressure under no-flow conditions, the cause could be thermal expansion, pressure creep, or dirt/debris on the seat.

• Thermal Expansion: Occurs when water is heated in a closed system. A system is closed when supply pressure exceeds 150psi, or a check valve or backflow preventer is installed. Provisions for pressure relief protection (e.g., Watts 530C, BRV, Governor 80, 3L relief valves, or Watts DET, PLT, DETA expansion tanks) may be required. To check for thermal expansion, briefly open a cold water tap; if pressure drops and returns to the set pressure, thermal expansion is the cause.
• Pressure Creep: Can occur if the valve is not properly adjusted or if there is internal leakage.
• Dirt/Debris: Foreign matter on the seat can prevent the valve from closing properly.

Watts offers a pressure test gauge, model 276H300, to help determine if you have high water pressure. This gauge, when attached to a hose bibb, registers the highest pressure reading over time.

Repair Kits

Typical and Series Installation Diagrams

Typical Installation: Shows a single pressure reducing valve installed in a water line.

Series Installation: Recommended for very high supply pressure reduction to a very low downstream pressure to eliminate whistling and noise. Pressure is reduced in stages.

Parallel Installation: Recommended for high flow or intermittent/occasional low flow demand, or where service interruption is not possible. Two valves are installed in parallel.

Limited Warranty

Watts Regulator Co. warrants each product to be free from defects in material and workmanship under normal usage for one year from the date of original shipment. The Company will, at its option, replace or recondition the product without charge if defects are found within the warranty period.

This warranty is expressly given and is the only warranty provided. Watts Regulator Co. disclaims all other warranties, express or implied, including implied warranties of merchantability and fitness for a particular purpose. The remedy described is the sole and exclusive remedy. Watts Regulator Co. is not responsible for incidental, special, or consequential damages, including lost profits or costs of repair/replacement of other property. This warranty is voided by abuse, misuse, misapplication, improper installation, or alteration.

Some states do not allow limitations on implied warranty duration or exclusion of incidental/consequential damages. Therefore, these limitations may not apply. This Limited Warranty grants specific legal rights, and other rights may vary by state. Consult applicable state laws for your rights.

To the extent consistent with applicable state law, any implied warranties that cannot be disclaimed are limited in duration to one year from the date of original shipment.

Contact Information

USA: 815 Chestnut St., No. Andover, MA 01845-6098; www.watts.com

Canada: 5435 North Service Rd., Burlington, ONT. L7L 5H7; www.wattscanada.ca