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

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

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

O-ring

Disc &

Spring

Assembly

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

in. in. mm

21⁄2– 3 10 250

415 380

615 380

823 580

10 25 640

▼

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.

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: (978) 689-6066 • Watts.com

Canada: T: (888) 208-8927 • Watts.ca

Latin America: T: (52) 55-4122-0138 • Watts.com

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