Specifications, Applications,
Service Instructions & Parts
FROST MASTER
®
&
FROST MASTER
®
PLUS
DEFROST CONTROLLERS
Bulletin F100d
JAN 2011
for Industrial/Commercial
Evaporator Defrosting
FM-71 Defrost Controller
INTRODUCTION
The Hansen Frost Master
®
is an easy-to-use defrost
controller for efficient removal of frost accumulation
on evaporator coil surfaces. This controller uses
simple, reliable solid-state electronics with a precision
quartz time clock and time adjusting slide knobs to
sequentially operate through logical defrost steps for
smooth but complete and effective defrosting. The
SPDT relays facilitate flexible connection of solenoid
valves and control relays. Defrost mode and step
times are easily viewed through the clear cover of the
NEMA 4 enclosure. Typically, one controller is used
per defrost control valve group.
KEY FEATURES
User friendly
SPDT relays, 10 amp switch rating
Entire program always visible
Battery back-up
Terminals for optional sensor defrost initiation
Terminals for optional sensor defrost termination
Staggered defrosting is simple
24 hour or 7-day scheduling
Precision quartz time clock
Remote Initiate only models available
APPLICATIONS
Designed specifically for defrosting industrial and
large commercial refrigeration systems, the Frost
Master
®
sequences solenoid valves and relays to
provide quick and efficient defrosting of evaporator
coils. Because of its SPDT relays and time adjustable
defrost steps, this controller is suitable for almost
every defrost application including: top and bottom
feed unit coolers, blast freezer evaporators, and
ice makers. Whether the evaporator uses hot gas,
electricity, or water to defrost, this controller makes
setting or changing defrost periods simple and easy.
A very precise quartz time clock facilitates accurate
setting of defrost start times. Time clocks include
battery back-up in case of short term power failure to
avoid any nuisance re-setting of clocks after power
interruptions.
Demand initiate and coil temperature terminate devices
may be directly connected to the Frost Master
®
when
something other than conventional time-only defrosting
is appropriate. The Frost Master
®
Plus
models offer
a built-in temperature terminate feature as well as an
additional defrost step, SOFT GAS, which can help
minimize pressure shock to the evaporator during
defrosting.
TABLE OF CONTENTS
Specifications, Advantages, Installation ........................ 2,3
Initiation, Termination, Wiring ........................................ 4,5
Frost Master
®
Plus
(SOFT GAS) ...................................... 6,7
Typical Defrost Applications ........................................... 8,9
Control Valve Selection ...............................................10,11
Remote Initiate Models, Order Info. ................................ 12
