User guide
ENGLISH INSTRUCTIONS
WATTS 
PRESSURE GAUGE
(2 PLACES)
WATTS 
SHUTOFF VALVE
(2 PLACES)
WATTS 
BACKFLOW
PREVENTER
WATTS 
PRESSURE 
REGULATOR
(2 PLACES)
WATER
METER
SUPPLY
TO FIXTURES
TO SILLCOCK
WATTS 
PRESSURE GAUGE
(2 PLACES)
WATTS 
SHUTOFF VALVE
(2 PLACES)
WATTS 
BACKFLOW
PREVENTER
WATTS 
PRESSURE 
REGULATOR
WATER
METER
SUPPLY
TO FIXTURES
TO SILLCOCK
Typical Installation
Series Installation
Series installations are recommended where very high supply  
pressure must be reduced to a very low downstream pressure. 
Reducing the pressure in stages eliminates whistling and noise.
Parallel Installation
Parallel installations are recommended where high flow or low flow 
demand is intermittent/occasional. They are also used for installations 
where service cannot be interrupted.
1. Mark pipe as shown.  
This is pipe insertion depth.
2. Clean pipe end.
1. Remove collet clip.
2. Depress collet.
3. Pull tubing from tailpiece.
3. If using PEX tubing, insert pipe stiff-
ener (provided) into end of pipe.
4. Push tubing into tailpiece up to mark.
5. Insert collet clip.
Quick-Connect Installation
To Connect:
To Disconnect:
WATTS 
PRESSURE GAUGE
(2 PLACES)
WATTS 
SHUTOFF VALVE
(2 PLACES)
WATTS 
BACKFLOW
PREVENTER
WATTS 
PRESSURE 
REGULATOR
(2 PLACES)
WATER
METER
SUPPLY
TO FIXTURES
TO SILLCOCK
IS-U5
LFU5B-Z3
LFU5B-QC-Z3
Troubleshooting
High System Pressure
If the downstream system pressure is higher than the set pressure under no flow condi-
tions, the cause could be thermal expansion, pressure creep or dirt/debris on the seat.
Thermal expansion occurs whenever water is heated in a closed system. The system is 
closed when supply pressure exceeds 150psi, or a check valve or backflow preventer is 
installed in the supply piping.
You must make provisions for pressure relief protection of your plumbing system and 
components. The use of a relief valve such as the Watts 530C, BRV, Governor 80, or 3L 
or potable water expansion tank such as the Watts DET, PLT or DETA may be required.
To determine if this is the result of thermal expansion, try briefly opening the cold water 
tap. If the increased pressure is caused by thermal expansion, the pressure will immedi-
ately be relieved and the system will return to the set pressure.
Watts offers a pressure test gauge, model LF276H300 to assist you in determining if 
you have high water pressure. The LF276H300 when attached to a hose bibb registers 
the highest pressure reading over the period of time it is left on the system.
Installation Guidelines
1.   The valve should be installed by a 
licensed contractor in accordance 
with local codes and ordinances.
2.   This valve should be installed where 
it is accessible with sufficient clear-
ance for cleaning, service, or adjust-
ment.
3.   Before installing the valve, be sure 
that the pipe ends are reamed and 
threads are cut to size. For valves 
with Quick-Connect tailpieces refer 
to “Quick-Connect Installation” 
instructions below. 
4.   Flush the lines to remove all loose 
scale, dirt and other foreign matter 
that can damage or clog the valve.
5.   Install the regulator with the arrow 
on the body pointing in the direction 
of the flow.
6.   Regulator may be installed vertically 
or horizontally (upright or inverted).
7.   Start Up — Open cold water supply 
then hot water supply. Inspect for 
leaks.
NOTICE
 The valve should be inspected annu-
ally to assure maximum life and perfor-
mance.
NOTICE
LFU5-M1 Valves are suitable for acces-
sible outdoor or pit installations.
Maintenance Instructions
• To clean strainer remove the bottom 
plug and pull out strainer.
Adjustment
Regulator is factory preset to 50psi (344 
kPa) in a static condition. To adjust 
pressure setting, loosen the lock nut 
and turn the adjusting bolt clockwise to 
increase pressure, counterclockwise to 
decrease pressure. 
CAUTION
!
Any time a reducing valve is adjusted, 
the use of a pressure gauge is recom-
mended to verify correct pressure set-
ting. Do not bottom out adjusting screw 
on spring cage.
S eries  LFU5B-Z3
S eries  LFU5B-Z3
S éries  LFU5B-Z3
Water Pressure Reducing Valve
Válvula reductora de la 
presión del agua
Régulateur de pression d'eau
1
⁄2" - 1" (15-25mm) 
Installation Instructions
Instrucciones 
de instalación
Instructions d’installation
PEX tubing only
Pipe Stiffener
Tail Piece
1
1
⁄2 in. (38.1mm)
1
3
⁄4 in. (44.45mm)
1
7
⁄8 in. (47.63mm)
1
⁄2 in.Pipe (12.7mm)
3
⁄4 in.Pipe (19.05mm)
1 in.Pipe (25.4mm)
Union Gasket
(for union  
models only)
Seat Gasket
Diaphragm
Seat
Disc Screw
Strainer Plug Gasket
Strainer screen
Bottom Plug Gasket
Disc
Dishwasher
Booster
Reducing 
Valve
Watts T&P Relief 
Valve
180° Rinse water
140° Incoming Water
Low Pressure 
Service
Recommended installation when 
regulator is used to control flow 
through the booster heater to 
dishwasher.
IS-U5 1329  EDP# 1911439  © 2013 Watts
Limited Warranty: Watts Regulator Co. (the “Company”) warrants each product to be free from defects 
in material and workmanship under normal usage for a period of one year from the date of original ship-
ment. In the event of such defects within the warranty period, the Company will, at its option, replace 
or recondition the product without charge. 
THE WARRANTY SET FORTH HEREIN IS GIVEN EXPRESSLY AND IS THE ONLY WARRANTY 
GIVEN BY THE COMPANY WITH RESPECT TO THE PRODUCT. THE COMPANY MAKES NO OTHER 
WARRANTIES, EXPRESS OR IMPLIED. THE COMPANY HEREBY SPECIFICALLY DISCLAIMS ALL 
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED 
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
The remedy described in the first paragraph of this warranty shall constitute the sole and exclusive 
remedy for breach of warranty, and the Company shall not be responsible for any incidental, special 
or consequential damages, including without limitation, lost profits or the cost of repairing or replacing 
other property which is damaged if this product does not work properly, other costs resulting from labor 
charges, delays, vandalism, negligence, fouling caused by foreign material, damage from adverse water 
conditions, chemical, or any other circumstances over which the Company has no control. This warranty 
shall be invalidated by any abuse, misuse, misapplication, improper installation or improper maintenance 
or alteration of the product. 
Some States do not allow limitations on how long an implied warranty lasts, and some States do not allow 
the exclusion or limitation of incidental or consequential damages. Therefore the above limitations may 
not apply to you. This Limited Warranty gives you specific legal rights, and you may have other rights 
that vary from State to State. You should consult applicable state laws to determine your rights. SO 
FAR AS IS CONSISTENT WITH APPLICABLE STATE LAW, ANY IMPLIED WARRANTIES THAT MAY NOT 
BE DISCLAIMED, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
A PARTICULAR PURPOSE, ARE LIMITED IN DURATION TO ONE YEAR FROM THE DATE OF ORIGINAL 
SHIPMENT.
IS-U5 1329  EDP# 1911439  © 2013 Watts
Garantía limitada: Watts Regulator Co. (en adelante, “la Compañía”) garantiza, por un período de un año a 
partir de la fecha de embarque original, que sus productos están libres de defectos en materiales y mano de obra 
bajo condiciones de uso normal. En caso de que se encuentren tales defectos dentro del período de garantía, la 
Compañía reemplazará o reacondicionará, a su elección, el producto sin costo alguno. 
LA GARANTÍA AQUÍ ESTIPULADA SE OTORGA EN FORMA EXPRESA Y ES LA ÚNICA GARANTÍA 
OTORGADA POR LA COMPAÑÍA EN RELACIÓN CON EL PRODUCTO. LA COMPAÑÍA NO OTORGA NINGUNA 
OTRA GARANTÍA, YA SEA EXPRESA O IMPLÍCITA. LA COMPAÑÍA POR LA PRESENTE RENUNCIA 
ESPECÍFICAMENTE A TODAS LAS DEMÁS GARANTÍAS, EXPRESAS O IMPLÍCITAS, INCLUYENDO SIN 
LIMITACIÓN, LAS GARANTÍAS IMPLÍCITAS DE APTITUD PARA LA COMERCIALIZACIÓN E IDONEIDAD PARA 
UN PROPÓSITO EN PARTICULAR. 
La solución descrita en el primer párrafo de esta garantía constituirá la única y exclusiva solución por 
incumplimiento de garantía, y la Compañía no se hará responsable por daños accidentales, especiales o 
indirectos, incluyendo sin limitación, la pérdida de ganancias o el costo de reparación o reemplazo de otra 
propiedad que resulte dañada por el mal funcionamiento de este producto, otros costos resultantes por mano 
de obra, retardos, vandalismo, negligencia, obstrucciones ocasionadas por materiales extraños, daños debidos 
a condiciones adversas del agua, químicos o cualquier otra circunstancia sobre la cual la Compañía no tenga 
control. Esta garantía no tendrá validez en cualquier caso de abuso, uso indebido, aplicación incorrecta, 
instalación inadecuada, o mantenimiento adecuado o alteración del producto. 
Algunos Estados no permiten limitaciones en la duración de una garantía implícita y algunos Estados no permiten 
la exclusión o limitación de daños accidentales o indirectos. Por lo tanto, es posible que las limitaciones anteriores 
no sean aplicables en su caso. Esta garantía limitada le da derechos legales específicos; usted podría tener tam-
bién otros derechos que varían según el Estado. Usted debe consultar las leyes estatales aplicables para deter-
minar sus derechos. EN LA MEDIDA EN QUE SEA CONGRUENTE CON LAS LEYES ESTATALES APLICABLES, 
CUALQUIER GARANTÍA IMPLÍCITA QUE NO SEA RECHAZADA, INCLUYENDO LAS GARANTÍAS IMPLÍCITAS DE 
APTITUD PARA LA COMERCIALIZACIÓN E IDONEIDAD PARA UN PROPÓSITO EN PARTICULAR, SE LIMITA EN 
SU DURACIÓN A UN AÑO A PARTIR DE LA FECHA DEL EMBARQUE ORIGINAL.
Garantie limitée :  Watts Regulator Co. (la « Société ») garantit que chacun de ses produits est exempt de 
vice de matériau et de fabrication dans des conditions normales d’utilisation pour une période de un an à 
compter de la date d’expédition d’origine. Dans l’éventualité où de tels vices se manifesteraient pendant 
la période de garantie, la Société, à sa discrétion, remplacera ou reconditionnera le produit sans frais. 
LA PRÉSENTE GARANTIE EST EXPRESSE ET REPRÉSENTE LA SEULE GARANTIE OFFERTE PAR 
LA SOCIÉTÉ POUR CE PRODUIT. LA SOCIÉTÉ N’OFFRE AUCUNE AUTRE GARANTIE, EXPRESSE OU 
TACITE. PAR LA PRÉSENTE, LA SOCIÉTÉ REJETTE SPÉCIFIQUEMENT TOUTE AUTRE GARANTIE, 
EXPRESSE OU TACITE, NOTAMMENT TOUTE GARANTIE TACITE DE QUALITÉ MARCHANDE OU 
D’ADAPTATION À UN BUT PARTICULIER. 
Le recours décrit dans le premier paragraphe de cette garantie constitue le seul recours à toute violation 
de la présente garantie. La Société ne saurait être tenue responsable de tout dommage accessoire, 
spécial ou indirect, y compris, de façon non limitative : la perte de profits ou le coût afférent à la 
réparation ou au remplacement d’autres biens qui seraient endommagés par suite du fonctionnement 
incorrect dudit produit ; d’autres coûts résultant de frais de main-d’œuvre, de retards, de vandalisme, 
de négligence, d’une obstruction causée par des matériaux étrangers, de dommages causés par une 
eau impropre, des produits chimiques ou par tout autre événement échappant au contrôle de la Société. 
La présente garantie est déclarée nulle et non avenue en cas d’usage abusif ou incorrect, d’application, 
d’installation ou d’entretien incorrects ou de modification du produit. 
Certains États n’autorisent pas les limitations de durée d’une garantie tacite ou l’exclusion ou la 
limitation des dommages accessoires ou indirects. Les limitations susmentionnées peuvent donc ne pas 
s’appliquer à vous. Cette garantie limitée vous donne des droits spécifiques et il se peut que vous ayez 
aussi d’autres droits qui varient d’un État à l’autre. Veuillez vous référer aux lois applicables de l’État pour 
déterminer vos droits en la matière. DANS LA MESURE PERMISE PAR LA LOI APPLICABLE DE L’ÉTAT, 
TOUTES LES GARANTIES TACITES NE POUVANT PAS ÊTRE REJETÉES, Y COMPRIS LES GARANTIES 
TACITES DE QUALITÉ MARCHANDE ET D’ADAPTATION À UN BUT PARTICULIER, SONT LIMITÉES 
QUANT À LEUR DURÉE À UN AN À COMPTER DE LA DATE D’EXPÉDITION D’ORIGINE.
IS-U5 1329  EDP# 1911439  © 2013 Watts
USA: Tel. (978) 688-1811 • Fax: (978) 794-1848 • www.watts.com
Canada:  Tel. (905) 332-4090 • Fax: (905) 332-7068 • www.watts.ca 
USA: Tél. (978) 688-1811 • Fax: (978) 794-1848 • www.watts.com
Canada:  Tél. (905) 332-4090 • Fax: (905) 332-7068 • www.watts.ca 
USA: Tel. (978) 688-1811 • Fax: (978) 794-1848 • www.watts.com
Canada:  Tel. (905) 332-4090 • Fax: (905) 332-7068 • www.watts.ca 
WARNING: This product contains chemicals known to the 
State of California to cause cancer and birth defects or other 
reproductive harm.
For more information: www.watts.com/prop65
ADVERTENCIA: Este producto contiene sustancias químicas 
que en el Estado de California se conocen como causantes 
de cáncer y malformaciones u otros daños reproductivos.
Para más información: www.watts.com/prop65
AVERTISSEMENT: Ce produit contient des produits chi-
miques reconnus par l’État de Californie comme étant can-
cérigènes et pouvant provoquer des anomalies congénitales 
ou affecter la capacité de reproduction.
Pour plus d'informations: www.watts.com/prop65
Bypass Feature
This regulator has a built-in thermal expansion bypass feature. This feature prevents 
downstream pressure from rising to more than 10psi above the supply pressure. 
NOTICE
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).
For repair kits and parts, refer to our price list 
PL-RP-GP found on www.watts.com.
Read this Manual BEFORE using this equipment.
Failure to read and follow all safety and use information can result in death, 
serious personal injury, property damage, or damage to the equipment.
Keep this Manual for future reference.
WARNING
!
For valves with CPVC or PEX end connections, do not exceed the
tubing manufacturers pressure and temperature ratings. Refer to the
tubing manufacturers product specications for that information.
WARNING
!
You are required to consult the local building and plumbing codes prior to 
installation. If the information in this manual is not consistent with local building 
or plumbing codes, the local codes should be followed. Inquire with governing 
authorities for additional local requirements.
WARNING
!


