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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

IS-25AUB    1734 

EDP# 1910200 

© 2017 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-25AUB    1734 

EDP# 1910200 

© 2017 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.

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 

stiffener (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-25AUB    1734 

EDP# 1910200 

© 2017 Watts

IS-25AUB

LF25AUB-Z3

LF25AUB-DU-QC-Z3

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 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 immediately be relieved and the system will return to the set pressure. Watts 

offers a pressure test gauge, model 276H300 to assist you in determining if you 

have high water pressure.
The 276H300 when attached to a hose bibb registers the highest pressure reading 

over the period of time it is left on the system.

Maintenance Instructions

•  To clean strainer; shut off inlet water pressure, remove strainer plug (2), 

remove and clean strainer.

•  To replace seat disc; shut off supply, loosen nut (51) and back off adjusting 

screw (53) remove spring cage (3), spring (52) and washer (62). Remove 

bottom plug (12) and gasket (101). Insert and hold screw driver in slot on top 

of stem while loosening seat disc holder (47) from bottom of stem (27).

•  To replace diaphragm; loosen lock nut (48) and remove lock washer (46), 

diaphragm plate (60) and diaphragm (20).

•  When reassembling apply a drop of low strength thread lock to disc holder.
• Open inlet water supply slowly.

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.

Any time a reducing valve is adjusted, use a pressure gauge to verify correct pressure setting. 

Do not bottom out adjusting screw on spring cage.

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

To tighten valve, first hand tighten fol-

lowed by 

1

4

-1 turn, using wrench.

The valve should be inspected annually 

to assure maximum life and performance.
Product is for interior or exterior applica-

tions. Product should not be buried direct-

ly in the ground. For exterior applications 

where the valve will be situated in a vault 

or pit or be in contact with the ground, the 

valve should be installed in a meter box/

vault, accessible for repair and adjustment, 

per local code.

Installation Instructions

Series LF25AUB-Z3

S  eries 

LF25AUB-Z3

S  éries 

LF25AUB-Z3

Water Pr

essure Reducing V

alve

Válvula r

eductora de la pr

esión 

del agua

Régulateur de pression d'eau

1

2

" - 2" (15-50mm) 

PEX tubing only

Pipe Stiffener

Tail Piece

Repair Kits

 Kit for Series LF25AUB-Z3 includes all items shown above

ORDERING CODE

KIT NO.

SIZE (DN)

in

mm

0864941

1

2

" LF25AUB-RK

1

2

15

0864943

3

4

" LF25AUB-RK

3

4

20

0864942

1" LF25AUB-RK

1

25

0864944

1

1

4

" LF25AUB-RK

1

1

4

32

0864945

1

1

2

" LF25AUB-RK

1

1

2

40

0864946

2" LF25AUB-RK

2

50

When Ordering, Specify: 

1. Ordering Code
2. Size of Valve
3. Type Number
4. Model shown on Nameplate

276H300

  (53)  - Adjusting Screw
  (51)  - Lock Nut
  (3) 

- Spring Cage

  (61)  - Spring Washer
  (52)  - Spring
  (48)  - Lock Nut
  (46)  - Lock Washer
  (60)  - Diaphragm Plate
  (20)  - Diaphragm †
  (102)  - Bypass Valve Gasket*
  (116)  - Bypass Valve Assembly*
  (103)  - O-Ring†
  (27)  - Stem
  (16)  - Seat†
  (42)  - Washer
  (37)  - Disc†
  (47)  - Disc Holder
  (104)  - Strainer Plug Gasket†
  (2) 

- Strainer Plug

  (6) 

- Bypass Ball**

  (77)  - Strainer
  (101)  - Bottom Plug Gasket†
  (12)  - Bottom Plug

*  Bypass Valve Assembly for 

1

1

4

" - 2" is replaceable as  

a sub assembly.

(77) - Strainer

(104) -  
Strainer Plug Gasket

(2) - Strainer Plug

 † Rubber Parts

 * Replaceable

** Non-Replaceable

**  (6) - Bypass Ball for 

1

2

" - 1" sizes only are 

non-replaceable.

Bypass Feature*

This regulator has a built-in 

thermal expan-sion bypass 

feature. This feature 

prevents downstream 

pressure from rising to 

more than 10psi above 

the supply pressure.
* The bypass feature will 

not prevent the pressure 

relief valve from opening 

on the hot water 

supply system 

withpressure above 

150psi (10.3 bar).

You are required to thoroughly read all installation instructions and product 

safety information before beginning the installation of this product. 

FAILURE 

TO COMPLY WITH PROPER INSTALLATION AND MAINTENANCE 

INSTRUCTIONS COULD RESULT IN PRODUCT FAILURE WHICH CAN 

CAUSE PROPERTY DAMAGE, PERSONAL INJURY AND/OR DEATH.

 

Watts is not responsible for damages resulting from improper installation and/or 

maintenance.
Local building or plumbing codes may require modifications to the information 

provided. You are required to consult the local building and plumbing codes prior 

to installation. If this information is not consistent with local building or plumbing 

codes, the local codes should be followed.

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 specifications for that information.

WARNING

!

WARNING

!

Installation Instructions • Instrucciones de instalación • Instructions d’installation

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

AVER

TISSEMENT: 

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

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

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)

WARNING

!

WARNING

!

USA:

 T. (978) 688-1811 • F: (978) 794-1848 • www.watts.com

Canada: 

T. (905) 332-4090 • F: (905) 332-7068 • www

.watts.ca 

Latin America:

 T: (52) 81-1001-8600 • watts.com

USA:

 T. (978) 688-1811 • F: (978) 794-1848 • www.watts.com

Canada: 

T. (905) 332-4090 • F: (905) 332-7068 • www

.watts.ca

Latin America:

 T: (52) 81-1001-8600 • watts.com 

USA:

 T: (978) 688-1811 • F: (978) 794-1848 • watts.com

Canada: 

T: (905) 332-4090 • F: (905) 332-7068 • watts.ca

Latin America:

 T: (52) 81-1001-8600 • watts.com

For valves with CPVC or PEX end connections, do not exceed the 

tubing manufacturers pressure and temperature ratings. Refer to the 

tubing manufacturers product specifications for that information.

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