Hansen FROST MASTER User manual

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

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F100d
JAN 2011
MATERIAL SPECIFICATIONS
Defrost Steps:
PUMPOUT 0 to 15 minutes
HOT GAS 0 to 45 minutes
EQUALIZE 0 to 5 minutes
FAN DELAY 0 to 5 minutes
(For Plus models, see page 6.)
Relays: SPDT, 10 amp rating each
Defrost Interval:
24 hour clock, 96 settings (15 min. increments)
7-day clock, 84 settings (2 hour increments)
Remote Initiate models, user selectable
Battery Back-Up: 90 hours for quartz time clock
Power: 115V 50/60Hz; 230V 50/60Hz
Terminal Strip: Accepts 14-22 AWG wire sizes
Controller Temperature Range: -20ºF to 120ºF (-29°C
to 50°C) ambient
Enclosure: NEMA 4, high impact polycarbonate clear
cover, gasketed
Auxiliary ¼” spade terminals for optional defrost
initiate or temperature terminate
ADVANTAGES
The control settings are in refrigeration terms, “defrost
steps”, which make setting and adjusting the Frost
Master® controller simple and easy to understand.
The defrost starts with the removal of liquid refrigerant
from the evaporator before starting the frost melt
period. PUMPOUT (step 1) reduces the load caused
by the cold residual liquid refrigerant and exposes
more internal surface area to the hot gas. HOT GAS
(step 2) introduces the hot gas (or other frost melting
medium) to the evaporator for a set period of time or
can be temperature terminated. EQUALIZE (step 3)
reduces the relatively high pressure inside the newly
defrosted evaporator, thus eliminating the sudden,
sometimes radical surge in suction pressure when
the suction solenoid valve is reopened. FAN DELAY
(step 4) freezes the water droplets from the melted
frost to the evaporator surface instead of permitting
them to blow into the refrigerated space. NORMAL
refrigeration resumes by star ting the fan motor.
Usage of all steps is at the designer’s option and any
step may be skipped by setting the defrost step time
adjustment to zero.
When used in conjunction with a Demand Initiate
Defrost device, this controller can limit the number
of defrosts per day or week by not defrosting unless
necessary; the time clock can be used to prevent
defrost from happening when it would not be
advantageous. Temperature terminate contacts are
provided to optionally connect a thermostat or other
device for minimized defrost time.
The Remote Initiate models (clockless) require only
an external, momentary dry contact closure of the
initiate terminals from a computer, PLC, push button,
etc. to start a defrost cycle. This facilitates great
flexibility in various and unusual applications. Frost
Master® Plus models are available having an additional
defrost step, SOFT GAS, to minimize pressure shock
when hot gas is introduced to evaporator. Also, these
models have a built-in temperature terminate feature;
see page 6.
INSTALLATION
Mount controller, which has a watertight enclosure,
in an indoor location away from potential impact
or vibration. To fasten, use four screws (0.5” or
longer); see installation dimensions below. Do not
exceed controller ambient temperature range. Allow
space below enclosure for electrical connections. A
½” conduit knockout (0.88” hole) is provided. Any
additional holes must be located at the bottom of the
enclosure to avoid dust and water damage. Conduit
fittings should be of a watertight seal design where
applicable. Install 5 amp fuse to protect controller
from electrical shorts; see pages 5 and 7.
The Frost Master® is available, less enclosure, with
metal mounting plate, for installation in electrical panel
or approved outdoor enclosure; see below.
INSTALLATION DIMENSIONS
WITH ENCLOSURE
LESS ENCLOSURE WITH METAL MOUNTING PLATE
0.19'' (5 mm) MOUNTING
BOTTOM VIEW
FRONT VIEW
(175 mm)
(157 mm)
(100 mm)
1/2'' CONDUIT KNOCK-OUT
ENCLOSURE BASE
COVER SCREWS (TYPICAL)
CLEAR COVER
3.94''
6.18''
6.89''
(175 mm)
(157 mm)
(29 mm)
1.13
HOLES LOCATED
BEHIND COVER SCREWS
6.89''
6.18''
(88 mm)
FMP
MODELS
ONLY
MODELS
ONLY
FMP
(128 mm)
5.05''3.45''
2.95''
(75 mm)
(75 mm)
2.95''
0.34''
0.34''
(9 mm)
(9 mm)
SIDE VIEWFRONT VIEW
0.19'' (5 mm) MOUNTING HOLES
4 PLACES
3.00'' (TYPICAL)
6.88''
7.25''
(175 mm)
(184 mm)
(41 mm)
(159 mm)
(76 mm)
(14 mm)
(86 mm)
6.25''
METAL MOUNTING PLATE
1.63'' (TYPICAL)
(1 mm)
0.19''
(5 mm)
0.03''
0.56''
3.38''

3F100d
JAN 2011
EQUALIZE: 0 to 5 minutes. The EQUALIZE step
permits gradual reduction of the pressure inside the
evaporator after defrosting to near suction pressure.
This is accomplished by either a bleed-down solenoid
valve by-passing the suction shut-off valve or by
merely allowing the surrounding ambient temperature
to cool the evaporator. This step lowers the internal
pressure and the likelihood of evaporator, piping
and component shock when the suction stop valve
is opened. Equalization also reduces the impact
of pressure changes upon the suction accumulator.
Radical pressure changes cause unnecessary loading
and unloading of compressors and also encourage
pumps to cavitate. Observing the evaporator pressure
gauge during this step may help determine the most
appropriate time setting.
FAN DELAY: 0 to 5 minutes. This step resumes
normal refrigeration but delays the evaporator fan
operation for the set time. This delay enables the
remaining water droplets from the melted frost to
freeze to the surface of the evaporator, thus preventing
them from blowing into the refrigerated space when
air flow resumes.
PUMPOUT: 0 to 15 minutes. The PUMPOUT step
helps in the removal of liquid refrigerant from the
evaporator before defrosting begins. Less liquid
means more internal evaporator surface is exposed to
entering hot gas. It also reduces the amount of liquid
accommodated by the system during defrost.
HOT GAS: 0 to 45 minutes. The HOT GAS step
begins the actual melting of the frost accumulation.
The amount of time required to remove the frost is
dependent on many factors including the following:
design of evaporator, quantity of frost accumulation,
quality and quantity of hot gas supply, size of valves,
etc. A fairly accurate way of setting this time is
by observing several defrosts of the evaporator
to estimate the amount of time required, possibly
by using the Manual Stepping feature of the Frost
Master®. Be sure that the HOT GAS step is long
enough to entirely remove every portion of the frost.
Partial removal of frost is not acceptable because
it will tend to increase in mass after each defrost,
eventually causing a large frost/ice problem. To help
assure complete defrosting where the HOT GAS step
duration is desired to be kept to a minimum, a coil
clean temperature terminate device is an option. (See
TERMINATE, page 4 and 6).
FROST MASTER® DEFROST CONTROLLER
NEMA 4 ENCLOSURE
LIGHTS FOR DEFROST
STEPS
DEFROST STEPS TIME
ADJUSTMENTS
CLAMP TYPE TERMINALS
GROUNDING SCREW
TIME-OF-DAY AT ARROWHEAD
QUARTZ TIME CLOCK
(24 HOUR OR 7-DAY)
TIME CLOCK TABS
“OPTIONAL INITIATE”
SPADE TERMINALS
“OPTIONAL TERMINATE”
SPADE TERMINALS
DEFROST MODE LIGHT
MANUAL INITIATE &
STEPPING BUTTON

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F100d
JAN 2011
SETTING DEFROST START TIMES
To set the time-of-day or day-of-the-week (7-day
clock) rotate the time clock clockwise until the exact
time matches up with the triangle shaped time marker
located on the inner dial. To set defrost start times,
push the time clock tabs next to the desired times
towards the center. Defrosts will begin at each of these
times, provided the initiate terminals are closed (for
time-only defrost, a factory installed, removable jumper
closes these terminals; see DEMAND INITIATE).
Typically, no more than a 1/3 of a plant’s evaporators
should be in defrost at one time because an adequate
supply of hot gas is required. About 100 psig minimum
of hot gas pressure should be available for ammonia
or a pressure equivalent to 40ºF (4°C) saturation
pressure plus about 30 psi line pressure drop for
other refrigerants.
For multiple evaporators with individual defrost
controllers, if necessary the defrost start time settings
can be staggered by 15 minutes (or multiples thereof)
and the 24 hour quartz time clock will maintain this
interval accurately. (The 7-day time clock can stagger
start times by 2 hours or multiples.) At least one tab
must be set away from the center of the time clock
between defrosts. Therefore, a ½ hour minimum
between defrosts for 24 hour time clocks and a 4 hour
minimum for 7-day clocks is required.
SETTING DEFROST STEPS
Each defrost step has its own slide knob time
adjustment. After determining the proper setting,
move each slide knob to a position corresponding
to an appropriate amount of time (minutes). Defrost
step lights will illuminate during each respective step
to inform operator of defrost status. After observing
several defrosts, the setting may be easily re-adjusted
to more closely match the actual conditions of the
application.
DEFROST STEP AND MODE LIGHTS
These lights inform the operator of defrost controller
status. A g re en L .E .D. light indicates normal
refrigeration. A combination of two red L.E.D. lights
indicates the defrost mode and its particular step. If
no lights are on, check power to controller.
MANUAL STEPPING
A manual stepping button is provided for initiating
and optionally advancing through the defrost steps.
This will be helpful when testing electrical operation
and connections, as well as manually initiating a
defrost during a period of unusual frost accumulation.
IMPORTANT: Control devices (solenoid valves, control
relays, etc.) can operate while using the manual
stepping button. Care should be taken not to advance
the defrost steps so rapidly that the evaporator, piping,
and other refrigerant components experience sudden
or unfavorable conditions.
DEMAND INITIATE
The defrost initiate feature is a normally open (N.O.) pair
of ¼” spade terminals (INIT). They must be closed and
a time clock tab must trip before a defrost will begin.
In other words, initiate for a clock equipped defrost
controller will only occur if called for by an initiation
device during a clock scheduled defrost period. On
the other hand, a “clockless” Remote Initiate Model
(FM-01, FM-02, FMP-01) could initiate defrost any
time the initiate device closed the terminals. The
Frost Master® is supplied with a factory installed
jumper wire which closes the initiate terminals. If a
remote demand initiate defrost device is to be used
for a clock model, simply cut and remove this small,
horizontal jumper wire which is soldered between
the base of the initiate terminals. Then connect the
normally open leads from the initiate device to the
initiate spade terminals.
The demand defrost cycle will occur only when the
time clock tabs are pushed in and when the initiate
device calls for defrost. This prevents defrosts from
occurring at inappropriate times. At least one time
clock tab must be set away from the center of the
time clock between defrost initiate times to “RE-ARM”
controller. If there are periods when a demand defrost
would not be advantageous (i.e. when loading a room
or at the beginning of a work shift), pull the time clock
tabs which correspond to these times away from the
center of the time clock. A defrost will not be able
to start during these times. Should a defrost be
requested by the initiate device during this restricted
time period, it will not start until the next following
pushed-in time clock tab time is reached. This is also
ideal in preventing too many or several evaporators
in the same room from going into defrost at once. It
is feasible to use a computer or similar device in lieu
of a frost sensor for demand initiate.
Frost Master® Remote Initiate Models (less any time
clock) offer many features suitable for computer
initiate, manual push button, and demand defrost
devices only; see page 12.
TERMINATE
The defrost terminate feature is a normally open (N.O.)
pair of ¼” spade terminals. When there is a closure
of these terminals during the HOT GAS step only,
the Frost Master® ceases hot gas defrost supply,
advances to EQUALIZE and proceeds at the set time
intervals through to the other steps. The coil clean
terminate device is usually a customer supplied
thermostat (temperature switch) set at about 40ºF
(4°C) whose sensing bulb is located at the last place
on the evaporator coil where frost or ice remains
during a defrost. By ending the HOT GAS step as
soon as the coil is clean, a quick and efficient defrost
occurs. When using a terminate device be sure that
the HOT GAS step duration setting is long enough to
always permit a complete defrost. If not sure, set to
maximum. If the terminate device or thermostat is not
actuated, the hot gas supply or other frost melting
medium will be terminated by this step time setting.
For defrost controller with built-in Temperature
Terminate feature and sensor, see Frost Master® Plus
models on page 6.

5F100d
JAN 2011
FROST MASTER® RELAY OPERATION
CONTROL VALVE
OR RELAY RELAY DEFROST STEPS NORMAL REFRIG.
PUMPOUT HOT GAS* EQUALIZE FAN DELAY
Liquid Solenoid L
Suction Solenoid S
Hot Gas Solenoid H
Equalize Solenoid E
Fan Motor Relay F
The table above indicates the relay positions during each defrost step and normal refrigeration.
* There is approximately a 5 second delay before the “H” relay switches to its position during this step. This
is to give the suction solenoid valve time to close before the hot gas solenoid valve opens.
WIRING DIAGRAM
The wiring diagram below is typical for the bottom feed evaporator shown on page 9. Other wiring schemes
are possible to meet system requirements. This wiring diagram is for illustration purposes only and does not
show all controls and safety devices. Final control wiring is the responsibility of the system designer. See
above table for relay operation.
Relays shown with no power to Frost Master®. See above for relay operation.
= RELAY ENERGIZED
POWER
INPUT
RELAY L RELAY S
NC
NC NO CNO
RELAY H
C C
NO
NC C
NO
NC C
NO
NC
RELAY E RELAY F
FAN MOTOR RELAY
HOT GAS SOLENOID VALVE
LIQUID SOLENOID VALVE
N
L
EQUALIZE SOLENOID VALVE
CONVENTIONAL SUCTION SOLENOID VALVE
FIELD
INSTALLED
5 AMP FUSE
INIT
TERM
1 2 3456 7 8 9 10 11 12 13 14 15 16 17
OPTIONAL
DEFROST
INITIATE
DEVICE
OPTIONAL
HOT GAS
TERMINATE
DEVICE
PILOT SOLENOID VALVE TO GAS-POWERED SUCTION STOP VALVE

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F100d
JAN 2011
FROST MASTER® PLUS DEFROST CONTROLLER
TERMINATE (PLUS MODELS)
The defrost terminate feature is built-in to the Frost
Master® Plus models. It consists of an accurate,
du r a b l e te mp e r a t u r e s e ns o r a n d a te r min a t e
temperature setting adjustment on the face of the
defrost controller. When the terminate temperature
is satisfied, the HOT GAS step (or even the SOFT GAS
step) will cease and the EQUALIZE step will begin.
By ending the HOT GAS step as soon as the coil is
clean, a quick and efficient defrost occurs. If the
terminate temperature feature is not desired, simply
do not connect the temperature sensor and the HOT
GAS step will operate on time only.
The terminate temperature adjustment setting range
is from 30ºF to 65ºF (-1°C to +18°C); and is usually
set about 40ºF (4°C). If the terminate temperature is
not reached, the hot gas supply or other frost melting
medium will be terminated by the HOT GAS step time
duration. Coincidentally, be sure that the HOT GAS
step setting duration is long enough to always permit
a complete defrost. If unsure, set time duration to
maximum.
Locate the terminate temperature sensor at the last
place of the evaporator coil where frost or ice remains
during a defrost. Fasten sensor to evaporator or
piping. Join each of two 6 ft. (183 cm) long sensor
wire leads to field sensor wires using the supplied
watertight solderless joint connectors. Carefully
crimp then heat to seal joint from moisture. Field
sensor wire size should be at least 20 AWG (0.5 mm2)
and limited to a distance of 500 ft. (152 m). Avoid
running wires through evaporator air stream or with
high voltage wiring. Connect field sensor wires to
terminate temperature sensor quick disconnect plug
inside defrost controller enclosure.
TERMINATE TEMPERATURE SENSOR
INTRODUCTION
This deluxe model, Frost Master® Plus, includes an
additional (fifth) defrost step, SOFT GAS, plus a built-
in, adjustable, Temperature Terminate feature with
clamp-on “defrosted” sensor. Also, the PUMPOUT
and EQUALIZE defrost step times are greater than
the standard Frost Master®; otherwise, operation
is the same.
The SOFT GAS step permits the gradual build-up of
pressure inside the evaporator. This is accomplished
by opening a small soft (hot) gas solenoid valve prior
to opening a primary hot gas solenoid valve during the
HOT GAS step. This primes the evaporator for hot gas
full flow. The soft gas solenoid valve will remain open
throughout the SOFT GAS and HOT GAS steps.
The built-in Temperature Terminate feature enables
operator to easily adjust the terminate temperature
setting without having to climb a ladder to reach the
thermostat (temperature switch) on an evaporator.
TYPICAL APPLICATION
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
TERMINATE TEMPERATURE
SETTING ADJUSTMENT
TERMINATE TEMPERATURE
SENSOR QUICK
DISCONNECT PLUG
RELAY SG (SOFT GAS)
TERMINALS
DEFROST STEPS
TIME ADJUSTMENTS
PUMPOUT: 0 TO 45 MIN
SOFT GAS: 0 TO 5 MIN
HOT GAS: 0 TO 45 MIN
EQUALIZE: 0 TO 10 MIN
FAN DELAY: 0 TO 5 MIN
0.50''
1.25''
0.25''
SIDE VIEW
TOP VIEW
(6 mm)
(32 mm)
(13 mm)
0.50''
1.25''
0.25''
SIDE VIEW
TOP VIEW
(6 mm)
(32 mm)
(13 mm)

7F100d
JAN 2011
FROST MASTER® PLUS RELAY OPERATION
CONTROL VALVE
OR RELAY RELAY DEFROST STEPS NORMAL REFRIG.
PUMPOUT SOFT GAS* HOT GAS EQUALIZE FAN DELAY
Liquid Solenoid L
Suction Solenoid S
Soft Gas Solenoid SG
Hot Gas Solenoid H
Equalize Solenoid E
Fan Motor Relay F
The table above indicates the relay positions during each defrost step and normal refrigeration.
* There is approximately a 5 second delay before the “SG” relay switches to its position during this step. This
is to give the suction solenoid valve time to close before the soft gas solenoid valve opens.
WIRING DIAGRAM
The wiring diagram below is typical for the bottom feed evaporator shown on page 9. Other wiring schemes
are possible to meet system requirements. This wiring diagram is for illustration purposes only and does not
show all controls and safety devices. Final control wiring is the responsibility of the system designer. See
above table for relay operation.
Relays shown with no power to Frost Master® Plus. See above for relay operation.
= RELAY ENERGIZED
POWER
INPUT
RELAY L RELAY S
NC
NC NO CNO
RELAY SG
C C
NO
NC C
NO
NC C
NO
NC
RELAY H RELAY E
HOT GAS SOLENOID VALVE
LIQUID SOLENOID VALVE
N
L
EQUALIZE SOLENOID VALVE
CONVENTIONAL SUCTION SOLENOID VALVE
FIELD
INSTALLED
5 AMP FUSE
INIT
1 2 3456 7 8 9 10 11 12 13 14 15 16 17
OPTIONAL
DEFROST
INITIATE
DEVICE
HOT GAS
TERMINATE
TEMP.
SENSOR
201918
RELAY F
NC NO C
FAN MOTOR RELAY
SOFT GAS SOLENOID VALVE
PILOT SOLENOID VALVE TO GAS-POWERED SUCTION STOP VALVE

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F100d
JAN 2011
INTRODUCTION TO DEFROSTING
While the most important component of the defrost
system is the controller, it is important to understand
the reasoning behind each defrost step as well as
other elements which contribute to a successful
and efficient defrost sequence. It is obvious that an
evaporator in defrost will not have a cooling effect on
the refrigerated space, therefore a minimum amount
of time in defrost is desirable. However, it is more
important to operate a safe and efficient defrost
than a speedy one. Defrosting of industrial/large
commercial evaporator coil surfaces is predominately
accomplished by the use of refrigerant hot (discharge)
gas. Other possible methods include: water, air,
electric assisted, or combination of several. Even
though hot gas defrosting is explained here, the
principles are generally the same whatever method
is used.
Key elements of a successful defrost system include
a reliable hot gas supply, control valves and a defrost
controller. The hot gas supply at the evaporator
should be free of condensate, sufficient in pressure
and quantity to effectively remove ice and frost from
the coil surfaces. Valves must be in place to control
the flow of hot gas into the evaporator, maintain
the pressure inside evaporator above an equivalent
saturation pressure of 32ºF (0°C) during defrost,
facilitate the removal of refrigerant liquid condensate,
limit the entry of hot gas to suction line and minimize
pressure shock when normal refrigeration is resumed.
The defrost controller should sequence control valves
in a manner which minimizes stress to evaporators,
piping and compressors. It should stop normal
refrigeration and pumpout the evaporator to expose
more internal coil surface to the incoming hot gas.
Optionally introduce hot gas via a smaller valve to
reduce pressure shock to evaporator, then continue
by opening a larger hot gas supply valve, but not for
an excessive amount of time. Reduce the pressure
inside the evaporator before opening main suction
valve to avoid suction pressure shock. Start normal
refrigeration but delay the fans until remaining water
droplets freeze to coil surfaces.
On the next page are typical application examples of
hot gas defrosting evaporators with control valves.
Although there are many ways to circuit a defrost
system, these illustrate some basic methods which
apply to most. In general, hot gas is introduced into
the top of the evaporator for even heat distribution
throughout coil. Refrigerant condensate is removed
from the bottom of the evaporator to minimizes the
amount of hot gas entering the suction line and to
provide a means of oil removal. Typically the defrost
relief regulator is set at about 70 psig (5 bar) for
ammonia. When a defrost condensate liquid drainer is
used, an outlet pressure regulator in the hot gas supply
line should be used to limit the internal evaporator
pressure. Check valves are installed after the liquid
solenoid valve to prevent higher pressure gas from
entering the liquid supply line during defrost. Also,
check valves are placed between the evaporator and
drain pan to keep the pan from accumulating frost
during the refrigeration cycle.
SOFT GAS VALVE
The purpose of the soft gas valve is to gradually
increase the pressure inside evaporator before
introducing full flow hot gas. This reduces the
possibility of pressure shock to coil which often has
residual liquid from the refrigeration cycle. The soft
gas valve should open several minutes prior to the main
hot gas valve. The evaporator need not be completely
at full hot gas pressure before hot gas valve is opened.
Generally, a soft gas valve should be used when the
hot gas solenoid valve is 1½” or larger. However, the
installation of a soft gas valve could be considered
on smaller circuits if the evaporator temperature is
below 0°F (-18°C) or it exhibits disturbances upon
opening of the hot gas valve.
The ideal soft gas valve size depends on many factors
including: evaporator volume, the use of a pumpout
step which removes residual refrigerant liquid, the
quality and quantity of the hot gas supply pressure,
etc. In most cases, a ½” port soft gas valve should
be sufficient; such as Hansen Type HS8A. A hand
expansion valve (regulator) or globe valve can be
installed just after the soft gas valve to fine tune
sizing.
EQUALIZE VALVE
The purpose of an equalize valve is to prevent
disturbances when opening main valve leading from
newly defrosted evaporator to suction pressure.
The equalize valve is to be opened several minutes
prior to the main valve. The evaporator need not be
completely equalized to suction pressure, rather the
purpose is to reduce the pressure differential to an
acceptable level. In general, it is recommended that
an equalize valve be installed on evaporators having
15 tons (53 kW) or greater capacity or a 2½” and larger
suction line. However, equalize valves may need to
be installed on smaller evaporators depending on
degree of disturbance upon opening main suction
valve. Many factors can increase the degree of
disturba nce, including: the pressure dif ference
between evaporator and suction, the amount of
liquid remaining in evaporator, the size of valves, the
complexity of piping, and etc.
The equalize valve size is a function of the evaporator
volume and the pressure difference. The valve typically
can be 3 or 4 sizes below main valve, but not less than
½” port. A hand expansion valve (regulator) or globe
valve can be installed just after the equalize valve to
fine tune sizing.

9F100d
JAN 2011
TYPICAL DEFROST APPLICATIONS
These are only examples of possible control valve schemes. As always, they are provided only to assist
system designer in applying and selecting valves and controls. Ultimately, designer is responsible for safe and
satisfactory operation of any defrost system.
HOT GAS SOLENOID VALVE
SOFT GAS SOLENOID VALVE
HOT GAS LINE
LIQUID SOLENOID VALVE
LIQUID LINE
OVERFEED
WITH ELECTRIC SHUT-OFF.
STOP VALVE, OR REGULATOR
OR GAS-POWERED SUCTION
SUCTION SOLENOID VALVE,
EQUALIZE SOLENOID VALVE
OVERFEED
SUCTION LINE
FAN
CHECK
VALVE
PAN
REGULATOR
DEFROST RELIEF
HOT GAS LINE
SOFT GAS SOLENOID VALVE
HOT GAS SOLENOID VALVE
CHECK
VALVE
PAN
FAN
LIQUID SOLENOID VALVE
WITH ELECTRIC SHUT-OFF.
STOP VALVE, OR REGULATOR
OR GAS-POWERED SUCTION
SUCTION SOLENOID VALVE,
FOR EQUALIZING
WITH WIDE OPENING FEATURE
DEFROST RELIEF REGULATOR
OVERFEED
LIQUID LINE
SUCTION LINE
OVERFEED
BOTTOM FEED EVAPORATOR TOP FEED EVAPORATOR
EVAPORATOR WITH GAS-POWERED
SUCTION STOP VALVE
EVAPORATOR WITH DEFROST
CONDENSATE LIQUID DRAINER
DEFROST RELIEF
HOT GAS SOLENOID VALVE
SOFT GAS SOLENOID VALVE
HOT GAS LINE
LIQUID LINE
OVERFEED
SUCTION LINE
OVERFEED
CHECK
VALVE
FAN
EQUALIZE SOLENOID VALVE
LIQUID SOLENOID VALVE
STOP VALVE
GAS-POWERED SUCTION
PAN
REGULATOR
OVERFEED
SOFT GAS SOLENOID VALVE
HOT GAS SOLENOID VALVE
HOT GAS LINE
LIQUID LINE
OVERFEED
SUCTION LINE
VALVE
CHECK
FAN
EQUALIZE SOLENOID VALVE
LOADED
DEFROST CONDENSATE
LIQUID SOLENOID VALVE
SUCTION SOLENOID VALVE,
OR GAS-POWERED SUCTION
STOP VALVE.
PAN
OUTLET PRESSURE
REGULATOR
CHECK VALVE
LIQUID DRAINER

10
F100d
JAN 2011
HOT GAS DEFROST NOMINAL VALVE SIZING (TONS)
REFRIG. APPLICATION PORT SIZE
3/4” 1” 1-1/4” 1-1/2” 2” 2-1/2”
R717 Hot Gas Solenoid 9 to 15 15 to 28 28 to 39 39 to 73 73 to 106 106 to 165
Defrost Relief Regulator 17 to 24 24 to 45 45 to 60 60 to 96 96 to 140 140 to 225
R22 Hot Gas Solenoid 6 to 8 8 to 15 15 to 20 20 to 32 32 to 47 47 to 75
Defrost Relief Regulator 6 to 8 8 to 15 15 to 20 20 to 32 32 to 47 47 to 75
Evaporator tons at 10ºF (5°C) temperature differential. Ideal sizing could var y with desired time for defrosting,
available supply pressure, amount of ice on evaporator, usage of pre-defrost pumpout, etc. For other control
valve sizing, see detailed Hansen bulletins on specific valve types.
VALVE SELECTION
* Type HCK2, HCK2W requires single pilot solenoid valve to operate and has minimal internal bleed to down stream side of main
valve. Type HS9B, HS9BW uses dual pilot solenoid valve assembly and has no internal bleed.
HT100 CONDENSATE
DRAINER
This unit is ideally suited for the
removal of liquid condensate from
hot gas mains and headers. Helps
assure refrigerant gas will be available at inlet of hot
gas supply valve leading to evaporator. This avoids
moving condensed liquid through valve before frost
melting can begin. Typical rating at 86ºF to 10ºF is
7.5 lbs./min. (0.063 kg/sec.) for ammonia and 24.5 lbs./
min. (0.117 kg/sec.) for R22. For greater capacities,
contact factory. Inlet/outlet connections: combination
¾” FPT/1”Weld.
HD101 DEFROST
CONDENSATE LIQUID
DRAINER
Mechanical/non- electrical float
regulator drains liquid condensate
from evaporator during defrost. It
has built-in gas vent plus expansion valve bypass as
is necessary to avoid gas binding. Suitable capacity
for 42 ton (147 kW) max. ammonia evaporator or 11
ton (39 kW) max. R22 evaporator; for larger capacities,
contact factory. Inlet/outlet connections: combination
¾” FPT/1” Weld.
DESCRIPTION PORT SIZES
1/2” 3/4” 1” 1-1/4” 1-1/2” 2” 2-1/2” 3” 4” 5” 6”
Liquid Line Solenoid
Valve HS8A HS7 HS4A
HS7
HS4A
HS7
HS4A HS4A HS4A HS4A − − − −
Suction
Line
Solenoid
Valve
Down
to -20ºF
(-30ºC)
−HS7
HS4A
HS7
HS4A
HS7
HS4A HS4A HS4A HS4A HS4A HS4A HS4W HS4W
Down
to -60ºF
(-50ºC)
Gas-
Powered
(Normally
Open)*
− − − HCK2 HCK2 HCK2 HCK2 HCK2 HCK2 HCK2W HCK2W
− − − HCK5 HCK5 HCK5 HCK5 HCK5 HCK5 HCK5W HCK5W
− − − HS9B HS9B HS9B HS9B HS9B HS9B HS9BW HS9BW
Hot Gas Line
Solenoid Valve HS8A HS7 HS4A
HS7
HS4A
HS7
HS4A HS4A HS4A HS4A − − − −
Defrost Relief
Regulator − HA4AK HA4AK HA4AK HA4AK HA4AK HA4AK − − − −
Defrost Relief
Regulator w/Wide
Opening
− HA4AB HA4AB HA4AB HA4AB HA4AB HA4AB − − − −
Equalize Line and
Soft Gas Solenoid
Valve
HS8A HS7
HS4A
HS7
HS4A
HS7
HS4A HS4A HS4A HS4A − − − −
Liquid Line and Drain
Pan Check Valve HCK4 HCK4 HCK4 HCK4 HCK4 HCK4 HCK4 − − − −

11 F100d
JAN 2011
CONTROL VALVES
Function of control valves: Provide hot gas to the
coil without liquid slug shocks, close the suction so
pressure can build-up, permit condensed refrigerant
liquid to exit the coil, control the pressure to a level
above freezing equivalent, and after defrost return
the coil gradually to plant suction pressure. Control
valves are available in ¾” thru 6” (20 mm thru 150 mm)
port sizes, unless otherwise stated.
HS8A SOLENOID VALVE
Normally spring closed, this valve opens
wide when energized. Ideally suited for
use as a soft gas, liquid or hot gas supply
valve. Available in ½” (13 mm) port size.
Optional close-coupled strainer (shown)
and pilot lights are available.
HS7 SOLENOID VALVE
Normally spring closed, this valve opens
wide when energized. Often used as a
liquid supply, hot gas or equalize valve
Available in ¾”, 1”, 1¼” (20, 25, 32 mm)
port sizes. Optional close- coupled
strainer (shown) and pilot lights are
available.
HS4A SOLENOID VALVE
Normally spring closed, this valve opens
wide when energized. Can be used as
a liquid line supply valve or suction
solenoid valve operating at 20F (-30C) or
above. Optional close-coupled strainer
and pilot lights are available.
HCK4 IN-LINE CHECK VALVE
These in-line check valves (disc type non-
return valves) open wide for flow in arrow
direction on valve body; promptly close
when flow reversals occur. Often they
are used on the outlet side of liquid line
solenoid valves leading to evaporators
to prevent hot gas from entering during
defrost. Also they are used between drain
pans and evaporators to keep pans from
developing frost during refrigeration and
after defrost relief regulators leading
to intermediate pressure suction lines.
They can be mounted in any position and
close-coupled to other valves.
HCK2 GAS-POWERED SUCTION
STOP VALVE
This valve is normally held open via a
spring and is gas-powered to close;
requires no pressure drop to operate.
Requires a single pilot solenoid valve
to control. Typically used to close-
off evaporators from system suction,
especially below -20F (-30C).
HS9B GAS-POWERED SOLENOID
VALVE
This valve uses a remote gas or liquid
pressure source to close; requires no
pressure drop to operate. Dual pilot
solenoid valve assembly controls opening
and closing of valve without internal bleed
to suction. This type of valve is often
used to shut-off liquid and gas legs of
gravity flooded evaporators .
HA4AD DUAL PRESSURE
REGULATOR
Regulates (evaporator) pressure at a
setting when energized, and at a higher
setting when de-energized. Used for
defrost pressure relief and pressure
control.
HA4AK RESEATING RELIEF
REGULATOR
Used for defrost relief to suction. This
control opens when system upstream
pressure is above the tagged and sealed
set point pre ssure, and r epeatedly
reseats after operation.
HA4AS REGULATOR WITH
ELECTRIC SHUT-OFF
This contr ol is comm on ly used for
temperature control or defrost. Regulates
at its set-for pressure when energized;
when de-energized, valve closes tight
regardless of pressure setting.
HA4AB REGULATOR WITH
ELECTRIC WIDE OPENING
Common ly r e gulate s for def ros t or
temperature, but opens wide for maximum
cooling or equalizing. Regulating at set
pressure when de-energized; regulator
opens wide when energized.
HA4AL DIFFERENTIAL
PRESSURE REGULATOR
Used commonly as liquid pump relief.
Avoids high discharge pressure from
developing when flow becomes restricted
du e to m ulti p le ev a por a to r s bein g
in defrost at one time. This control
modu l a te s t o m a int a i n th e set-f o r
difference between inlet and outlet
pressure.
HA4AO OUTLET PRESSURE
REGULATOR
Controls outlet pressure by opening as
downstream pressure falls below setting.
Used to limit hot gas pressure supply in
defrosting evaporators in conjunction
with defrost condensate liquid drainers
or for regulating pressure in hot gas
remains. Can be combined with electric
shut-off, dual or wide opening features.
HA4AD
HA4AK
HA4AS
HA4AB
HA4AL
HA4AO
HS8
HS4A
HS7
HCK4
HCK2
HS9B

12
F100d
JAN 2011
Hansen Technologies Corporation
400 Quadrangle Dr, Suite F
Bolingbrook, Illinois 60440 USA
Tel: [phone] Fax: [phone] Toll: 800.426.7368
Email: [email protected] Web: www.hantech.com
USA ∙ Asia ∙ Europe ∙ India ∙ LatinAmerica ∙ MiddleEast
© 2011 Hansen Technologies Corporation
CAUTION
Hansen Frost Master® defrost controls are only for
refrigeration systems. These instructions and related
safety precautions must be read completely and
understood before selecting, using, or servicing these
controls. Only knowledgeable, trained refrigeration
mechanics should install, operate, or service these
controls. Stated electrical and temperature ranges
should not be exceeded. Any wiring and application
diagrams provided are for illustration purposes only.
The system designer has the final responsibility as
to how these defrost controls are connected, set and
operated. The designer is also responsible for systems
and components being designed to prevent abnormal
pressures or velocity impact pressure surges. Where
critical temperatures or products are involved, back-
up temperature controls or alarms are required. See
also Safety Precautions in current List Price Bulletin
and Safety Precautions Sheet supplied with product.
Escaping refrigerant might cause personal injury,
particularly to the eyes and lungs.
SERVICE AND MAINTENANCE
These controllers require practically no service or
maintenance. The only field replaceable components
are the time clocks (24 hour clock, -A suffix, p/n
67-0007 or -B suffix, p/n 67-0029; or 7 day clock, -A
suffix, p/n 67-0009 or -B suffix, p/n 67-0030) for all
models and the terminate temperature sensor (p/n 67-
0052) for the Frost Master® Plus. To replace clock,
disconnect all power to control unit. Remove each
of three 5/32” socket cap screws located at corners
of clock. Carefully pry clock away with hand. Install
new clock by inserting its spade terminals into the
clamp connectors located on the controller. Replace
screws, restore power, and set time-of-day and defrost
start times.
WARRANTY
Hansen defrost controllers are guaranteed against
defective materials or workmanship for 90 days F.O.B.
our plant. No consequential damages or field labor
is included.
REMOTE INITIATE MODELS
Remote Initiate Models FM-01, FM-02 and FMP-01 are
supplied less any time clock and horizontal jumper
wire. The defrost begins when the initiate spade
terminals are momentarily closed. The next defrost
will occur as soon as the present defrost is completed
and the initiate terminals are opened and then re-
closed. This model is especially well suited for use
with plant computers, PLC’s, production equipment
control relays, push buttons, etc.
TYPICAL SPECIFICATIONS
“Defrost controls shall have the ability to pump down
evaporator, apply hot gas for frost removal, equalize
evaporator pressure, and delay fans. Furthermore,
they shall provide connections for optional initiate and
terminate defrost devices, be capable of staggering
defrosts so as not to allow too many evaporators or
evaporators in close proximity to one another from
going into defrost at the same time. They shall provide
a remote initiate device connection, or 24 hour or 7-day
scheduling time clock with battery back-up in case of
short term power failure as manufactured by Hansen
Technologies Corporation or approved equal.”
ORDERING INFORMATION
CAT. NO. DESCRIPTION WT.
LBS.
FM-11 Frost Master® with enclosure 24
hour clock; 115V, 50/60Hz 4
FM-71 Frost Master® with enclosure
7-day clock; 115v, 50/60Hz 4
FM-01 Frost Master® with enclosure
Remote Initiate; 115V, 50/60Hz 4
FM-12 Frost Master® with enclosure 24
hour clock; 230V, 50/60Hz 4
FM-72 Frost Master® with enclosure
7-day clock; 230V, 50/60Hz 4
FM-02 Frost Master® with enclosure
Remote Initiate; 230V, 50/60Hz 4
For any of above Frost Master® less enclosure with
metal mounting plate, add “L” suffix to catalog number;
Example: FM-11L.
TO ORDER: Specify Catalog Number.
FROST MASTER® PLUS
CAT.
NO. DESCRIPTION WT. LBS.
FMP-11
Frost Master® Plus
with enclosure, 24 hour clock;
115V, 50/60Hz
4
FMP-71
Frost Master® Plus
with enclosure, 7-day clock;
115V, 50/60Hz
4
FMP-01
Frost Master® Plus
with enclosure, Remote Initiate;
115V, 50/60Hz
4
REMOTE INITIATE MODEL: FM-01