Watts 709 Series Operating instructions

Installation, Maintenance, and Repair Manual
Series 709, LF709, 709DCDA
Double Check Valve Assemblies
Double Check Detector Assemblies
21⁄2" – 10"
RP/IS-709/709DCDA
Testing
For field testing procedure, refer to Watts installation sheets
IS-TK-DL, IS-TK-7, IS-TK-9A, IS-TK-99D, and IS-TK-99E at
www.watts.com.
For other repair kits and service parts, refer to the Backflow
Prevention Products Repair Kits & Service Parts price list
PL-RP-BPD at www.watts.com.
For technical assistance, contact your local Watts representative.
NOTICE
For Australia and New Zealand, line strainers should be installed
between the upstream shutoff valve and the inlet of the backflow
preventer.
This device must be tested periodically in compliance with local
codes, but at least once per year or more as service conditions
warrant. If installed on a fire sprinkler system, all mechanical
checks, such as alarm checks and backflow preventers, should
be flow tested and inspected internally in accordance with NFPA
13 and NFPA 25.
WARNING
!
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.
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
the information provided here is not consistent with local
building or plumbing codes, the local codes should be
followed. This product must be installed by a licensed
contractor in accordance with local codes and ordinances.
WARNING
!
Need for Periodic Inspection/Maintenance: This product
must be tested periodically in compliance with local codes,
but at least once per year or more as service conditions
warrant. All products must be retested once maintenance
has been performed. Corrosive water conditions and/or
unauthorized adjustments or repair could render the product
ineffective for the service intended. Regular checking and
cleaning of the product’s internal and external components
helps assure maximum life and proper product function.
WARNING
!
Series 709 (21⁄2" to 10"), LF709 (21⁄2" to 10"), and 709DCDA
(3" to 10") assemblies help prevent the reverse flow of polluted
water from entering the potable water system. Series LF709
Model IOT includes factory-installed pressure sensors.
LF709-NRS-IOT
NOTICE
Use of integrated pressure sensors on and monitoring connection
kit with IOT models does not remove the need to comply with all
required instructions, codes, and regulations related to installation,
operation, and maintenance of the backflow preventer.
Watts®is not responsible for data transmission failures due to
power issues.
NOTICE
For IOT models, an add-on monitoring connection kit is required
to collect psi measurements from the integrated pressure sensors.
Without the connection kit, the pressure sensors are passive
components and will not communicate with any other device. For
BMS only. (The connection kit and pressure sensors are also avail-
able for existing installations. See “Add-on Monitoring Connection
Kits,” for ordering details.)
709 OS&Y

2
Vertical
Horizontal
LF709S
Strainer
Meter Strainer
LF709S
Parallel
Two or more assemblies may be piped in parallel (where
approved) to serve a large supply pipe main, as shown in Figure
3. This type of installation is employed whenever it is vital to
maintain a continuous supply of water where interruptions
for testing and servicing would be unacceptable. It also has
the advantage of providing increased capacity where needed
beyond that provided by a single valve.
For two valve installations the total capacity of the devices
should equal or exceed that required by the system. The
capacity table shows the size of the assemblies required to
meet a certain capacity. The quantity of devices used in parallel
should be determined by the judgment of the compliance
engineer, based on the operating conditions of a specific
installation.
Outside Building Above Ground
In area where freezing conditions do not occur, the series
can be installed outside of a building. The most satisfactory
installation is above ground and should be installed in this
manner whenever possible.
Avoid installing backflow preventers in pits unless absolutely
necessary and then only when approved by local codes. In
such cases, a modified pit installation is preferred or an above
ground insulated enclosure, as shown in Figure 2.
709/LF709
Indoors
The series can be installed in either vertical or horizontal
position, as shown in Figure 1. Approvals may vary by size
or model. Refer to ES-709. ES-LF709, and ES-709DCDA for
complete installation approval details.
Always install the valve in an accessible location to facilitate
testing and servicing. Do not install the unit in a concealed
location.
Pipelines should be thoroughly flushed to remove foreign material
before installing the unit. A strainer should be installed ahead of
the backflow preventer to prevent the disc from unnecessary
fouling. Install valve inline with the arrow on valve body pointing
in the direction of flow.
Capacity Required for System
Total capacity provided with dual valve installations of various sizes
450 GPM 640 GPM 1000 GPM 2000 GPM 3000 GPM 5000 GPM
Two 21⁄2"
devices
Two 3"
devices
Two 4"
devices
Two 6"
devices
Two 8"
devices
Two 10"
devices
WattsBox Insulated Enclosures
Available in Aluminum or Fiberglass.
For more information, refer to ES-WB at www.watts.com.
CAUTION
!
Do not install with a strainer when the backflow preventer is
affixed to seldom-used water lines that are called upon during
emergencies, such as fire sprinkler lines.
The series must be tested periodically in compliance with local
codes, but at least once a year or more often depending upon
system conditions.
Figure 1
Figure 2
Figure 3
Installation Guidelines

3
Spring Retainer
(Do Not Remove)
Spring
O-ring
Spring Retainer
(Do Not Remove)
Disc
Disc Holder
Retaining Ring
Disc Retainer Allen Head
Socket
Screws
Stem
Disc Holder
21⁄2", 3"
4" - 10"
Cover
Cover
O-ring
Disc &
Spring
Assembly
Seat
Seat
O-ring
Retainer
Wire
Servicing First and Second Check Valves
CAUTION
!
The series are designed so that, when the bolts are backed off
1⁄2", all the spring load is released from the cover and retained
by the check module. Verify this before removing all the bolts.
1. Remove hatch cover bolts.
2. Lift check valve module straight out, taking care not to hit
and damage seat ring.
3. Remove the seat ring for replacement by pulling out the two
10" wire retainers. One wire is drawn out clockwise; the
other, counterclockwise.
4. With the retainer wires removed, lift the seat ring straight up
to remove it.
CAUTION
!
The check valve disc-and-spring assembly are in compression.
The spring load is captured by the two spring retainers and the
stem. The spring retainers are not to be removed for servicing.
If there is a need to replace the spring, spring retainer, or stem,
replace the disc-and-spring assembly.
If the disc holder has been damaged by freezing or severe
water hammer, it can be replaced in the field. Remove the disc
holder retaining ring and slide the disc holder off the stem.
Remove the O-ring from the stem and replace it with a new
one. Apply grease to the O-ring and slide the new disc holder
into place. Reinstall the retaining ring.
NOTICE
The disc holder should not be removed when servicing only the
disc, remove the Allen head screws holding the disc retaining
plate and replace the disc.
WARNING
!
The disc-and-spring assembly assembly is factory assembled.
DO NOT DISASSEMBLE.
Clearance Required for Servicing
SIZE DIMENSION
A
in. in. mm
21⁄2– 3 10 250
415 380
615 380
823 580
10 25 640
▼
▼
A

Troubleshooting
Limited Warranty: Watts (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 shipment.
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.
RP/IS-709/709DCDA 2304 0835235 © 2023 Watts
Add-on Monitoring Connection Kits
ORDERING CODE ADD-ON/REPLACEMENT KIT DESCRIPTION
88003067 BF-BMS-MCK
BMS Monitoring Connection Kit
Series LF709 Model IOT
Sizes 2½" to 10"
Includes a turnkey solution for transmitting valve assembly
pressure measurements to a building management sys-
tem; consists of an interface module with three (3) sensor
cables, data cable, and power adapter.
88003068 RK-BF-Sensors
Pressure Sensor Module
Replacement Kit
Series LF709 Model IOT
Sizes 2½" to 10"
Includes three (3) replacement pressure sensor modules
for installation on test cocks No. 2, No. 3, and No. 4.
SYMPTOM CAUSE SOLUTION
Check valve fails to hold
1.0 PSID minimum
Debris on check disc sealing surface Disassemble and clean
Leaking gate valve Disassemble and clean or repair
Damaged seat disc or seat O-ring Disassemble and replace
Damaged guide holding check open Disassemble and clean or replace
Weak or broken spring Disassemble and replace spring
Chatter during flow conditions Worn, damaged or defective guide Disassemble and repair or replace guide
Low flows passing through
mainline valve
Mainline check fouled Disassemble and clean
Meter strainer plugged Disassemble and clean
Damaged mainline seat disc or seat Disassemble and replace
Broken mainline spring Disassemble and replace
USA: T: [phone] • Watts.com
Canada: T: [phone] • Watts.ca
Latin America: T: (52) 55-4122-0138 • Watts.com