Install Instructions
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.
IS-25AUB 1226  EDP# 1910200  © 2012 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 1226  EDP# 1910200  © 2012 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 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-25AUB 1226  EDP# 1910200  © 2012 Watts
IS-25AUB
25AUB-Z3
25AUB-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 expan-
sion 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 bot-
tom 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), dia-
phragm 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). To adjust pressure setting, loosen 
the lock nut and turn the adjusting bolt clockwise to increase pressure, counter-
clockwise to decrease pressure.
CAUTION: Any time a reducing valve is adjusted, the use of a pressure gauge is recom-
mended 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 suf-
ficient clearance for cleaning, ser-
vice, or adjustment.
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 direc-
tion of the flow.
6.   Regulator may be installed verti-
cally or horizontally (upright or 
inverted).
7.   Start Up — Open cold water sup-
ply then hot water supply. Inspect 
for leaks.
Note:   The valve should be inspected 
annually to assure maximum life 
and performance.
Note: 25AUB-Z3 or LF25AUB-Z3 valves 
are suitable for accessible outdoor 
or pit installations.
Installation Instructions
Series 25AUB-Z3 
and LF25AUB-Z3
S eries  25AUB-Z3  y 
LF25AUB-Z3
S éries  25AUB-Z3  et 
LF25AUB-Z3
Water Pressure Reducing Valve
Válvula reductora de la  
presión del agua
Régulateur de pression d'eau 
1
⁄2" - 2" (15-50mm) 
Installation Instructions
Instrucciones 
de instalación
Instructions d’installation
1-1/2 in. (38.1 mm)
1-3/4 in. (44.45 mm)
1-7/8 in. (47.63 mm)
1 in. Pipe (25.4 mm)
¾ in. Pipe 
(19.05 mm)
½ in. Pipe (12.7mm)
PEX
PEX tubing only
Pipe Stiffener
Mark
Collet clip
Collet depressed
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)
Repair Kits
†
 Kit for Series 25AUB-Z3 includes all items shown above
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 
  (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.
ORDERING CODE KIT NO. SIZE (DN)
in mm
0864941
1
⁄2" 25AUB-RK
1
⁄2 15
0864943
3
⁄4" 25AUB-RK
3
⁄4 20
0864942 1" 25AUB-RK 1 25
0864944 1
1
⁄4" 25AUB-RK 1
1
⁄4 32
0864945 1
1
⁄2" 25AUB-RK 1
1
⁄2 40
0864946 2" 25AUB-RK 2 50
When Ordering, Specify: 
1. Ordering Code 
2. Size of Valve 
3. Type Number 
4. Model shown on Nameplate
276H300
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 with 
pressure 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 COM-
PLY 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
!


