
Pilot
1. Remove the protecting cover from the top flange 
of the valve and flange of the pilot. Mount the pilot 
to the valve as shown in Figure 3.
2. Screw No. 4A bleedport fitting into the 1/8 in. / 
3.18 mm pipe tap on the outlet side of the main 
valve body. Note that the bleed orifice in this fitting 
is vital to the operation of the regulator. 
3. Screw No. 4B coupling into 1/8 in. / 3.18 mm pipe 
tap in pilot.
4. Screw No. 5A elbow containing the restriction 
orifice into the 1/8 in. / 3.18 mm pipe tap on the 
underside of the main valve diaphragm chamber. 
Type E2 main valves use a No. 5B elbow 
without orifice.
5. Connect the tubing bends as illustrated in Figure 3 
for Type E and E2 main valves.
Control Pipe
1. Use 1/4 in. / 6.35 mm pipe for this line which 
connects the pilot pressure diaphragm chamber to 
the desired point of pressure control. See Figure 3.
2. On instantaneous heaters with steam in shell, tap 
the control pipe into the shell. Otherwise, enter 
the delivery steam pipe at point of entrance to the 
heater. (See Figure 2)
3. Pitch the control pipe away from the pilot and 
avoid water pockets.
Insulation
Insulation may be applied to the upper portion (globe 
and flanges) of the main valve. Do not insulate the 
diaphragm chamber or any part of the pilot. See 
Figure 3.
Starting Up and Setting 
Controlled Temperature
Best temperature control will result when the delivery 
pressure setting is the lowest steam pressure capable 
of sustaining the desired temperature at maximum 
load. The following adjustments should be made under 
full load conditions or as near such as possible:
1. Close by-pass. Open 1/4 in. / 6.35 mm control 
pipe valve and turn up temperature adjusting 
wheel, until 1/2 in. / 12.7 mm of thread is exposed. 
Back off pressure adjusting screw to remove all 
compression from pressure limit spring. (See 
Figure 3)
Planning the Installation
1. Locate the regulator in a horizontal pipe.
2. Prevent water hammer and erratic operation by 
providing a trap ahead of the regulator.
3. Avoid damaging the effects of scale and dirt 
in pipe lines by using a strainer to protect 
the regulator.
4. Provide a three-valve by-pass to facilitate inspection 
of the regulator without interrupting service.
5. Thermostat position:
a. The preferred thermostat position is horizontal.
b. When vertical or slanting, the tip of the bulb 
must point downward.
c. Locate the thermostat as close to the heater 
outlet as practical.
d. Expose the entire length of the bulb to the 
active flow leaving the heater.
6. If the pressure rating of the heater or the 
connected equipment is less than the initial stream 
pressure, provide a safety valve.
7. Hot water and similar liquid systems require a 
relief valve to prevent dangerous overpressure 
due to expansion.
8. Instantaneous Heaters - When operated on 
intermittent demand, as in domestic water 
heating, require the following conditions for best 
temperature regulation.
a. Constant forced recirculation of fluid through 
the heater.
b. Omission of thermostat well to reduce 
temperature lag. Use of a thermostat 
compatible with the heated medium is preferred 
over the use of a standard thermostat installed 
in a well, which is compatible with the heated 
medium. When the use of a well is unavoidable, 
an appropriate heat transfer medium should be 
installed between the well and the thermostat.
Main Valve
1. Flush the piping system thoroughly to clear it of 
welding beads, scale, sand, etc.
2. Mount the main valve with the diaphragm chamber 
down and arrow on body pointing in the direction 
of the flow.
4
ET124 and ET134 Series