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Bulletin-MC-INST-MMA-0615 
Warranty & Engineering Data 
MACON CONTROLS 
NON-ELECTRIC 
THERMOSTATICALLY 
CONTROLLED RADIATOR 
VALVES 
APPLICATION 
The Valve Body is used with the Thermostatic 
Head to provide automatic control of baseboard 
units, convectors, or standing radiators in hot 
water systems and in 2-pipe steam heat systems. 
For 1-pipe steam systems, a 1-pipe steam radiator 
adapter assembly is available. A temperature 
sensitive element in the head modulates the valve 
in response to room temperature. Neither the 
valve nor the thermostatic head requires the use 
of electric power. 
INSTALLATION 
CAUTION 
1.  Installer must be a trained, experienced 
serviceperson. 
2.  When installing the valve body, the arrow 
must be in the direction of flow. 
3.  Always conduct a thorough checkout when 
installation is complete. 
IMPORTANT 
1.  On Straight-through body models, do not 
install with thermostatic head directly above 
valve body. On angle body models, assemble 
with thermostatic head on the far side of the 
valve from the heating surfaces to minimize 
the effects of radiant heat. 
2.  If boiler for 1-pipe steam system is cycled by 
a space thermostat in one zone, do not apply 
a radiator valve to the radiator in that zone. 
3.  Do not apply a radiator valve in 1-pipe steam 
systems that do not use steam air vent valves 
venting to atmosphere on each radiation unit. 
LOCATION 
The valve may be used to control radiators, 
baseboard units or convectors in single or multi-
zone hot water systems. The valve is used in 1-
pipe (monoflo) or 2-pipe heating systems. When 
the valve is used to control a single radiator, 
baseboard unit or convector, the valve is installed 
on the inlet side (Fig. 1A). When a valve is used 
to control a series of radiators or baseboards, the 
valve should be installed on the return side of the 
series run (Fig. 1B). In a multi-zone heating 
system with a single radiator, baseboard unit, or 
convector in each zone, a valve is installed on the 
inlet side of each radiator in each zone (Fig. 1C 
and 1D). In a multi-zone heating system with a 
series of radiators or baseboards in a single zone, 
install the valve on the return side of the series 
run (Fig. 1D). In a 1-pipe steam system, a 
vacuum breaker must be installed between the 
steam vent and the radiator (Fig. 9). 
IMPORTANT 
The location of the valve depends on the location 
of the thermostatic head. Be sure the thermo-
static head is NOT located where it is subject to 
drafts, exposed to direct sunlight, or covered by 
draperies or curtains. Note: When installing the 
Thermostatic Head for remote mounting, the 
hole in the mounting surface must be plugged 
with suitable insulation to insure that it receives 
minimal radiated heat and properly senses room 
temperature. 
VALVE BODY INSTALLATION 
The valve body must be installed within the 
following specified limits: 
Max. Static Pressure: 145 psig 
Max. Differential Pressure: 20 psig 
Sug. Differential Pressure: .5 to 2.9 psi 
Max. Steam Pressure: 15 psig 
Max. Water Temperature: 250°F 
When installing the valve body in water and 2-
pipe steam systems, the arrow must point in the 
direction of flow. For valve bodies with NPT 
threads, use new, properly reamed pipe, free of 
chips. Valve distortion or malfunction may result 
from excess pipe within the valve body. 
For valves with sweat fittings: 
IMPORTANT 
Insert assembly MUST be removed from valve 
bodies with sweat fittings before installation to 
avoid heat damage to rubber components 
(Fig. 2). 
1.  Use steel wool to thoroughly clean areas 
inside of valve into which copper tubing fits 
and approximately ¾ inch(19mm) at ends of 
tubing. 
2.  Apply small amount of solder flux around 
outside ends of tubing. 
3.  Insert both pieces of tubing completely into 
valve body. 
4.  Use a propane torch to heat valve body at the 
general area in which tubing is fitted. 
Note: The hole in cover must be at least as 
large as the knurled setting knob on the 
thermostatic head to allow for baseboard 
cover removal. 
5.  When valve body and tubing reach melting 
temperature of solder, apply solder to joint. 
Solder should draw evenly around fitting. 
6.  Do not disturb until solder sets up. 
7.  After cooling reinstall insert and visibly 
inspect for leaks with water supply turned 
on. 
8.  If leak is found, drain water and repeat 
soldering procedure. Remember, only a 
clean, fluxed joint which is free from water 
will accept solder. 
Note: Protective cap on body may be used to 
manually operate valve before head is installed. 
THERMOSTATIC HEAD 
INSTALLATION 
Models MTW 
Direct Mounting on Radiator 
Use the following procedure (Fig. 3): 
1.  Install the valve body on the radiator. 
2.  Remove the protective dust cover from the 
valve body. Do not discard it. 
3.  Open thermostat to highest number. 
4.  Install the thermostatic head to the valve 
body, do not over tighten thermostat nut, 
finger tighten, snug 1/4 turn with wrench. 
Fig. 3  Typical Installation of Valve (Angle 
  Body) on Radiator
Direct Mounting on Radiator 
Use the following procedure (Fig. 4): 
1.  Install the valve body on the baseboard unit. 
2.  Cut a hole in the baseboard unit directly in 
front of the valve connection. 
Note: The hole must be at least as large as 
the knurled setting knob on the thermostatic 
head to allow for base board cover removal. 
3.  Remove the protective dust cover from the 
valve body. 
4.  Open thermostat to highest number. 
5.  Install the thermostatic head to the valve 
body, do not over tighten thermostat nut, 
finger tighten, snug 1/4 turn with wrench. 
6.  Replace the baseboard cover. 
7.  Install pipe collar (collar not supplied) 
around the insulating sleeve. 
Fig. 4  Typical Installation of Direct Mount 
  Thermostatic Head in Baseboard
Models B46000 (ENTL) Fig. 5 
Remote Wall Mounting 
The Thermostatic Sensor is remote mounted 
from the valve on a plasterboard wall. 
IMPORTANT 
When selecting a location to mount the thermo-
static head, remember it must not be subject to 
drafts, exposed to direct sunlight, or covered by 
draperies or curtains. To mount the thermostat on 
a wall, use the following procedure (Figs. 5 & 8): 
1.  Select a location to mount the thermostatic 
head. In making the selection, locate the wall 
studs. Unnecessary and troublesome work 
can be avoided by mounting the thermostatic 
head and running the capillary between 2 
wall studs. 
2.  After selecting a location, prepare two 
openings 1½ inches in diameter. Prepare one 
opening near the actuator behind the base-
board unit or convector and one at the 
thermostatic head location. 
  Note: Capillary is 6’6” long. 
3.  Open thermostat to highest number. 
4.  Install the thermostatic head to the valve 
body, do not over tighten thermostat nut, 
finger tighten, snug 1/4 turn with wrench. 
5.  Replace the baseboard unit or convector 
cover. 
Important: Do not mount thermostat directly 
 over cover. 
Fig. 5  Typical Wall Mounting of ENTL 
  Installation for Convectors 
*Important:  Do not mount sensor directly over 
 baseboard unit. 
Fig. 6  Typical Wall Mounting of MTWZ 
  Installation for Baseboard 
Models MTWZ (Fig. 7) 
Remote Sensor Mounting 
Use the following procedure (Fig. 6 & 7): 
1.  Install the valve body on the radiator. 
2.  Remove the protective dust cover from the 
valve body. 
3.  Open thermostat to highest number. 
4.  Install the thermostatic head to the valve 
body, do not over tighten thermostat nut, 
finger tighten, snug 1/4 turn with wrench. 
5.  Select a sensor location. 
  Note: When selecting a location, remember 
that the sensor must not be exposed to drafts 
or direct sunlight, or covered by curtains or 
draperies. 
7.  Mount the sensor guard to the wall with 2 
screws (not supplied). 
8.  Snap the sensor bulb into place on the sensor 
guard base. 
9.  Snap the sensor guard cover into place on 
the sensor guard base. 
Models B56000-ENTLZ (Fig. 8) 
Remote Wall Mounting 
Use the following procedure (Fig. 8): 
1.  Select a location on the wall to mount the 
dial. In making the selection, locate the wall 
studs and mount the dial so the capillary can 
be flush mounted. 
2.  After selecting a location, drill 2 holes 1½ 
inches in diameter, one at the dial location, 
the other behind the baseboard or convector 
unit. Note: Each capillary is 6’6” long. 
*Important:  Do not locate sensor behind 
  curtains, drapes or in direct sunlight. 
Fig. 7 Typical Free Standing Radiator 
Installation 
3.  Feed the actuator through the hole at the dial 
location behind the wall and out through the 
second hole. 
4.  Install the valve body. 
5.  Remove the protective cover from the valve 
body. 
6.  Open thermostat to highest number. 
7.  Install the thermostatic head to the valve 
body, do not over tighten thermostat nut, 
finger tighten, snug 1/4 turn with wrench. 
8.  Secure the dial to the unit cover with 4 
screws (not supplied). Snap cover into place. 
9.  Mount the sensor below the radiation in the 
return air. Note: Secure the sensor guard 
base to the wall with 2 screws (not sup-
plied). Snap the sensor bulb into place. The 
sensor guard cover may be used if desired. 
Remote Mounting on Unit Cover 
Use the following procedure (Fig. 8): 
1.  Install the valve body. 
2.  Select a location for the dial and drill a 1½ 
inch diameter hole at the location. 
3.  Feed the actuator through the hole to the 
valve body. 
4.  Remove the protective cover from the valve 
body. 
5.  Install the actuator on the valve body. 
*Important: Do not locate sensor behind 
Tunstall Corporation 
118 Exchange St 
Chicopee, MA 01013 
Ph. 413-594-8695 • Fax 413-598-8109 
www.maconcontrols.com 
Contact your local distributor for parts 
Fig. 1  Valve Location in Single and 
  Multi-zone Hot Water Heating. 
curtains, drapes or in direct sunlight. 
Fig. 8 Typical Wall Mounting of ENTLZ 
Installation for Convectors 
CHECKOUT 
When the installation is complete, rotate the dial 
until steam or water flow is detected. After the 
room temperature has stabilized (4 or 5 hours), 
reset the dial to the desired setting between 1 and 
7 for MTW Series. (See chart on back page for 
temperature settings.) The set point will vary 
with the location of the sensor. A floor level 
sensor on a baseboard radiator will control at a 
different set point than a wall level sensor. 
Note: Repositioning of the actuator head may be 
necessary for convenient visibility of the index 
mark. Loosen the union between the actuator 
head and the valve body. Turn the actuator head 
to the desired position and retighten the actuator 
nut. 
SERVICE (All Models) 
Recalibration 
The thermostatic head is factory calibrated and 
should not need calibration. If, however, you feel 
that recalibration is required please contact 
factory. 
CAUTION 
Be careful not to damage “O” rings. 
Insert Replacement 
1.  Relieve system pressure and drain below 
level of valve. 
2.  Remove thermostatic head. 
3. Unscrew insert. 
4.  Screw new insert into body. 
5.  Replace thermostatic head and refill system. 
ONE-PIPE STEAM SYSTEMS (Fig. 9) 
Be sure boiler is cycled. 
Keep pressure as low as possible (1-1/2 psi 
recommended). 
1.  Use direct or remote Thermostat with one-
pipe steam valve. 
2.  Install as shown in Fig. 9. Note: Steam air 
vent must be mounted in upright position. 
Vacuum breaker required. 
3.  If the boiler is being cycled by a space 
thermostat, do not install a valve in this 
Fig. 2 NT Series Insert 










