Brochure

Tunstall Corporation
118 Exchange Street • Chicopee, MA 01013
© July 2014
We reserve the right to alter designs, specifications and information without notice.
Phone [phone] · Fax [phone]
www.tunstall-inc.com • www.maconcontrols.com
Bulletin-OPSK-0714
Non-Electric Operators
ONE-PIPE STEAM VALVE ASSEMBLY
OPSK
OPERATION
The Macon one-pipe steam valve assembly con-
sists of the reliable MTW direct mounting ther-
mostat. The thermostatic head contains a tem-
perature sensitive wax which expands and con-
tracts on a rise and fall of temperature in the
sensed area. When the temperature rises above
the temperature selected, pressure from the ex-
panding wax closes the valve, preventing or re-
stricting the flow of steam through the radiation
unit. When the room temperature drops below the
selected temperature, the valve opens and allows
an increase of steam flow through the radiation
unit. This modulating process continues automati-
cally to maintain the temperature you selected.
The OPSK controls room temperature by regulat-
ing the amount of air and steam in the radiator.
FEATURES & BENEFITS
• Compact dimensions
• Nickel-plated, forged brass valve
• Thermostat may be locked at or limited to any
desired temperature or temperature range
• Actuators may be changed without shutting
down the system
• Valve may be installed by dropping the sys-
tem down to zero pressure
• Individual room control for greater comfort
• Replaceable insert
• Stainless steel spindle
• Fuel savings up to 30%
• Nonelectric - fully automatic
• Prevents over- and under-heating
• Reliability
• Remote thermostats available - call or write
for the distributor nearest you!
• Vent and vacuum breaker included
• The OPSK helps to minimize large tempera-
ture swings inherent in one pipe steam sys-
tems.
OPTIONS
The OPSK can be fitted with the following
thermostatic operators:
• MTW (Standard) - direct mount
• MTWZ - direct mount w/remote sensor
• ENTL - remote dial
• ENTLZ - remote dial w/remote sensor
• VM Series - electric actuator
• Other operators available - contact factory
Important:
1. Installing the OPSK does not eliminate other controls in the system. The boiler must be cycled in some manner so that
condensate can return to the boiler and eliminate boiler flooding.
2. If the boiler is cycled from a space thermostat in one zone, do not apply a radiator valve to that zone’s radiation.
3. Do not apply a radiator valve in a one-pipe steam system that does not use steam air vents venting to the atmosphere on
each radiation unit.
4. The VB-18 vacuum breaker is recommended and assists in the return of condensate. Integral installation reduces vacuum
problems.
5. Very effective with system pressure range 0-1½ PSI. Suggested maximum operating pressure 2 PSI.