Install Instructions
RP/IS-7
Installation, Maintenance, & Repair 
Series 7 Dual Check Valves
LF7/7, LF7R, LF07S/07S, LF7C/7C, 7B, LFL7/L7, and LFCu7/Cu7
Sizes: 
1
⁄2" – 2" (15 – 50mm)
Water Meter
L7
to Sill Cock
Water 
Supply
to Fire sprinklers
07S
Main
Supply
Water Pressure 
Reducing Valve
1. Mark pipe as shown.  
This is pipe insertion depth.
2. Clean pipe end.
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.
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)
Quick-Connect Installation
To Connect:
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 IN-
STRUCTIONS 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 informa-
tion 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.
Need for Periodic Inspection/Maintenance: This product must be test-
ed periodically in compliance with local codes, but at least once per year 
or more as service conditions warrant. 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 inter-
nal components helps assure maximum life and proper product function.
WARNING
!
When a pressure reducing valve or dual check valve is installed in the 
supple line, it creates a closed system which makes plumbing code 
compliance imperative for system safety. Special attention must be 
given by all concerned to assure pressure relief protection is provided 
to protect water heater equipment. It is important to make certain an 
approved ANSI Z21.22 temperature and pressure relief valve is installed 
on the storage water heater. This device is designed for emergency 
safety relief and should not be used as an operating control.
High System Pressure
If the downstream system pressure is higher than the set pressure 
under a no flow condition, the cause could be thermal expansion. 
Thermal expansion occurs whenever is heated in a closed system.
You must make provisions for thermal expansion protection of your 
plumbing system and components when installing a pressure reducing 
valve or dual check valve in the supply line.
The use of pressure relief valves such as *Watts 530C, *BRV, 
*Governor 80, *3L and or a potable water expansion tank such as the 
Watts DETA and PLT may be required.
To determine if this is the result of thermal expansion, try briefly open-
ing 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.
*NOTE: The Watts 530C, BRV, Governor 80 and 3L 
are not ASME approved safety relief valves. Under no 
circumstances should these devices be used in place 
of an ASME approved valve. Consult your local water 
code authority to ensure installation compliance.
Watts product specifications in U.S. customary units and metric are approximate 
and are provided for reference only. For precise measurements, please contact 
Watts Technical Service. Watts reserves the right to change or modify product 
design, construction, specifications, or materials without prior notice and without 
incurring any obligation to make such changes and modifications on Watts prod-
ucts previously or subsequently sold.
Basic Installation Instructions
A.   Watts dual check valves may be installed in either a vertical or a horizon-
tal position. Series 7 & LF7 should be installed downstream of the water 
meter and of the water pressure regulator. All outlets including sill cocks 
must be downstream of the Series 7. Model 07S & LF07S should be 
installed at the fire sprinkler service connection to the main line.
B.   They should always be installed in an accessible location to facilitate 
the removal for servicing and testing.
C.   Pipe lines should be thoroughly flushed to remove foreign material 
before installing the unit.
D.   Protect from freezing
E.   Ensure that valve is installed in proper flow direction. Refer to flow 
direction arrow on valve nameplate or body.
F.   When installing valve in pipe line, only use wrenching flats provided. 
Do not apply wrench to body of valve. This will prevent distorting the 
valve body and component parts.
G.   These valves incorporate an O-ring union seal that requires minimum 
tightening of union nut. Do not overtighten.
H.   These valves contain plastic check modules and should never be 
directly sweated into the line. Sweat fit adapters should be sweated 
into the line prior to valve installation. 
I.   Avoid improper application and excessive pipe sealants such as tef-
lon
®
 tape and pipe dope.
1. Remove collet clip.
2. Depress collet.
3. Pull tubing from tailpiece.
To Disconnect:
Watts 276H300
WARNING
!


