Checking Mixing Valve
1. CHECKING COLD WATER SHUT-OFF. Shut off hot
supply keeping cold supply open. At first, full volume of
cold water should pass through valve. The volume of
cold water should then be reduced to a very small flow.
Failure of this to occur would indicate:
a. Piston #15 is stuck in one position. Unit has to be
cleaned.
b. Valve spring #18 has lost its strength and must be
replaced.
c. Cold water is in excess of 80°F.
2. CHECKING HOT WATER SHUT-OFF. Open both the
hot and cold supplies to mixing valve. Water should flow
through valve at 110°F. If not, adjust valve as explained
under “TEMPERATURE ADJUSTMENT.”
Now shut off the cold water supply to the mixing valve.
A properly operating mixer will shut off the hot water
almost instantly with hot water temperature supplying
the mixing valve at least 15 degrees higher than
maximum setting.
Failure to do so would indicate:
a. Dirt between the hot seat #17 in liner #21 and
piston #15 prevents it from closing. Unit has to be
cleaned.
b. The piston #15 could be stuck so that it cannot
move because of scale or some other deposit in
water. Unit has to be cleaned.
c. The thermostat has lost its power and has to be
replaced with a new one.
Inspection and Cleaning Valve
Shut off hot and cold water supply to mixing valve. Remove
body screws #9. Take the cover #26 off valve body. The
thermostat, piston and liner can now be examined.
Checking the Thermostat
If cold seat #23 on thermostat is worn or deeply indented,
remove it and replace with a new one. If there is a question
as to the thermostat being good, hold thermostat under
cold water faucet and insert an eraser-capped pencil into
the center of thermostat. Make a reference mark where
pencil protrudes from the thermostat. Now place the entire
thermostat into hot water, approximately 125°F for about
one minute. Remove thermostat from water, examine the
reference mark on pencil again. At this temperature, it
should extend out from former position about 1/8”. If it does
not, a new thermostat should be installed.
CAUTION: Extreme care should be exercised when
placing thermostat in and out of hot water.
Mixing valve
Valve is carefully assembled and tested at the factory and
set to deliver water at any temperature between full cold
and 115°F. Failure of the cold water supply will cause the
hot water seat to close. The label on the valve cover is
marked “WARMER - COOLER,” so that the temperature set
screw can be set accordingly.
Stop and Check Valves
Each inlet of the mixing valve must have a screwdriver-
operated check valve. Both the cold and hot water stop
and check valves must be open at all times for proper
functioning of the valve.
The stop and check valves serve two purposes:
1. They prevent the hot or cold water from by-passing
through the mixing valve.
2. They provide convenient means to shut the supplies to
the mixer for cleaning or repairs.
Stop and checks are required whenever downstream shut
off devices are used.
Temperature Adjustment
The temperature of the hot water supplying the mixing
valve should be at least 15 degrees higher than maximum
required valve setting. Valves are normally set at factory
for 115°F maximum outlet temperature with 140°F inlet. If
readjustment is required, proceed as follows:
1. Remove outside acorn nut #2.
2. With narrow blade screwdriver, turn adjusting set screw
#5 clockwise to reduce the outlet temperature and
counterclockwise to increase outlet temperature. The
set screw should not be turned more than 1/2 turn at a
time without testing water temperature.
3. When temperature is correct, replace acorn nut.
Adjusting screw #5 may not be turned counter-clockwise
more than 1-1/2 turns.
CAUTION: It is not recommended to set maximum
outlet temperature above the applicable plumbing code.
Piping Instructions
Before installing the mixer, blow out all pipe lines to be sure
that no dirt, such as pipe chips, wicking or lead, can enter
the mixing valve. Valve inlets are marked hot and cold.
Piping must go to proper inlets.
Maintenance
The Lawler thermostatic mixer should be checked
periodically for proper operation and cleaning. See
“INSPECTION AND CLEANING VALVE.” To test mixing
valve for proper setting and operation—proceed as follows:
