Pipe lines in a water supply system must be of sufficient carry-
ing capacity to maintain adequate pressure at the most remote
or highest fixture. Under the maximum probable fixture use, mini-
mum adequate pressure is generally 8 to 15 lbs. but may be more,
depending on the equipment being supplied. Relatively high ser-
vice pressures which can create high water velocities in pipe lines
would allow use of smaller pipes to satisfy fixture use. However,
high velocity tends to cause whistling and humming. Reduction
of pressure by the use of a pressure reducing valve, in an at-
tempt to eliminate such a condition, may reduce pipe line capaci-
ties below that which is adequate for maximum probable use.
When high service pressures are in effect, either continuously or
periodically, the application of a pressure reducing valve will be
successful only when the installed pipe line is of adequate size
to satisfy the system demand at the lower pressure. When actual
water demands are unknown, the valve size should be no less
then the existing pipe size.
PROBLEM
POSSIBLE CAUSE OR CAUSES
1.
Pressure creeps or builds up in system above
the setting of pressure reducing valve.
A. Thermal expansion of water as it is being heated.
B. Foreign matter on seating face of seal ring.
C. Cut, worn or chipped seal ring.
D. Cut or worn stem o-ring or worn o-ring groove.
SOLUTION
a. This is a natural consequence. It may happen each time that the heater runs. A pressure relief valve or
expansion tank must be installed. This will not prevent pressure rise but should limit it to a safe level.
b. Flush the reducing valve by opening one or two fixture outlets wide. If this does not correct the problem,
remove seal ring for cleaning.
c. Replace with new seal ring. Temporary repairs may be made by turning the seal ring over.
d. Replace with new stem o-ring and/or cartridge.
Troubleshooting
2.
Pressure and fixture flow is unsteady.
A. Low water supply pressure in mains caused possibly by
high area demand during certain periods of the day.
B. Heavy periodic demands by appliances in the house.
SOLUTION
a. This is a water department problem. It is due to the mains being inadequate for the demands made on them.
b. House service lines may at times be inadequate for the load. Size of some pipelines may need to be in-
creased. Pressure setting of reducing valve may be too low.
c. Try increasing pressure before changing pipelines.
3.
Small, inadequate flow from fixtures.
A. Pipelines to fixtures may be too small or house main
supply may be inadequate for normal fixture demand.
B. Heavy periodic demands by appliances in the house.
C. Screen clogged with debris.
SOLUTION
a. It may be necessary to increase pipe sizes only in some sections of the system leading to the offending ap-
pliances or fixtures. Increasing the house service mains might be necessary if small
supply is general at all fixtures.
b. Raise pressure gradually by readjusting valve until this point is determined.
c. Clean screen.
4.
Valve appears to be noisy; hums, whistles or
chatters.
A. Hum or whistle is usually caused by a high velocity
of flow in pipelines causing vibration.
B. Chatter usually originates with worn seat washer or
loosely installed seal ring.
SOLUTION
a. Pipelines could be small or too light. Reducing valves could be too small. Pipes and valves being small would
accentuate this condition.
b. Inspect seal ring. If a deep channel appears on seal ring face, replace or use the opposite side.
c. Frequently noise appears in a faucet or appliance and seems to originate from the reducing valve. There is a
general tendency to use streamline piping of a relatively small size. Velocity is naturally high and noise of fast
moving water is not unusual.
WILKINS OPERATION OF ZURN PLUMBING PRODUCTS
1747 Commerce Way, Paso Robles, CA 93446 Phone:805/238-7100 Fax:805/238-5766
a
company
ISBR4EC (REV. 7/03)
5.
Relief valve discharges continuously.
SOLUTION
a. Inspect regulator for debris; clean and reassemble.
b. Replace relief valve.
c. Lower temperature setting on water heater.
A.
Regulator is fouled by debris.
B.
Relief valve is fouled by debris.
C.
Pressure build up due to thermal expansion.
