Note: Installation and maintenance are to be performed only by qualified personnel who are familiar with local codes and
regulations, and are experienced with this type of equipment. Caution: Sharp edges are a potential injury hazard. Avoid contact
with them.
Transportation and Storage
Upon receipt of the equipment, check carton for visible
damage. Make a notation on the shipper’s delivery ticket
before signing. If there is any evidence of rough handling, the
cartons should be opened at once to check for concealed
damage. If any damage is found, notify the carrier within 48
hours to establish your claim and request their inspection
and a report. The Warranty Claims Department should then
be contacted.
Do not stand or transport the machines on end. For
storing, each carton is marked with “up” arrows.
In the event that elevator transfer makes upended posi-
tioning unavoidable, absolutely insure that the machine is in
the normal upright position for at least 24 hours before
operating.
Temporary storage at the jobsite must be indoors, completely shielded from rain, snow, etc. High or low temperatures naturally associated with weather patterns will not
harm the conditioners. Excessively high temperatures of
o
140
F (60oC) may deteriorate certain plastic materials and
cause permanent damage. In addition, the solid-state circuit
boards may experience operational problems.
Installation
General
1. To prevent damage, this equipment should not be operated for supplementary heating and cooling during the
construction period.
2. Inspect the carton for any specific tagging numbers as
requested by the installing contractor. At this time the
voltage, phase and capacity should be checked against
the plans.
3. Check the unit size against the plans to be sure that the
unit will be installed in the correct location.
4. Before installation, check the available closet dimensions
versus the dimensions of the unit.
5. Pay attention to the location and routing of water piping,
and electrical wiring. The locations of these items are
clearly marked on submittal drawings.
6. The installing contractor will find it beneficial to confer
with piping, sheet metal, ceiling and electrical foremen
together before installing any conditioners.
7. Remove shipping block from under the fan wheel.
8. We recommend that the contractor cover the conditioners with plastic film to protect the machines during finishing of the building. This is important if spraying fireproofing material on bar joists, sandblasting, spray painting
and plastering operations have not been completed. If
plastic film is not available, the shipping carton may be
modified to cover the units during construction.
9. On extra-quiet construction units with spring mounted
compressors, remove the shipping block under the compressor.
Page 2 / IM 407
Page 3
Unit location
1. Locate the unit in an area that allows for easy removal of
the filter and access panels, and has enough space for
service personnel to perform maintenance or repair. Provide sufficient room to make water, electrical and duct
connections.
2. The contractor should make sure that access has been
provided including clearance for duct collars and fittings
at water and electrical connections.
3. Allow adequate room around the unit for a condensate
trap.
4. The unit can be installed “free standing” in an equipment
room; however, closet installations are more common for
small vertical type units. Generally, the unit is located in
the corner of a closet with the nonducted return air facing
90o to the door and the major access panels facing the
door as in Figure 1A. Alternatively, the unit can have a
ducted return air with the opening facing the door and the
major access panels facing 90
Figure 1A. Typical closet installation with louver door return
o
to the door as in Figure 1B.
5. It is recommended that the unit be located on top of a
vibration absorbing material such as rubber or carpet to
reduce any vibration. See Figure 5.
6. If optional field installed controls are required (boilerless
system), space must be provided for the enclosure to
mount around the corner from the electrical entrances. Do
not locate the side of the unit too close to a wall. See
Figures 1A and 1B.
Minimum distance requirement from return air duct
collar to wall, for non-ducted units.
ModelDistance
007 – 012 .......................... 4 inches
015 – 019 .......................... 5 inches
024 – 030 .......................... 6 inches
036 – 042 .......................... 7 inches
048 – 060 .......................... 8 inches
Filter access
Each unit is shipped with a filter bracket for side filter removal.
Heat Pump
With Left-Hand
Return Air Arrangement
Return
Air
Opt. Controls
Elec. Entrance
Main Access Panel
Condensate
Water Supply
Water Return
Louvered Door
RisersReturn Air Thru
Figure 1B. Typical closet installation with ducted return
Heat Pump
Return
Duct &
Grille
With Left-Hand
Return Air Arrangement
Air
Opt. Controls
Elec. Entrance
Main Access PanelMain Access Panel
Heat Pump
With Right-Hand
Return Air Arrangement
Opt. Controls
Elec. Entrance
Main Access Panel
Condensate
Water Supply
Water Return
Return Air Thru
Louvered Door
Heat Pump
With Right-Hand
Return Air Arrangement
Opt. Controls
Elec. Entrance
NOTE: Minimum distance
Return
requirement for non-ducted
Air
units. (see chart above)
Return
Air
Duct &
Grille
Condensate
Water Supply
Water Return
Condensate
Water Supply
Water Return
Risers
IM 407 / Page 3
Page 4
Ductwork and attenuation
Discharge ductwork is normally used with these conditioners. Return air ductwork may also be required, but will require
field installation of a return air duct collar/2" (51mm) filter rack
kit.
All ductwork should conform to industry standards of
good practice as described in ASHRAE Systems Guide.
The discharge duct system will normally consist of a
flexible connector at the unit, a noninsulated transition piece
to the full duct size, a short run of duct, an elbow without
vanes, and a trunk duct teeing into a branch circuit with
discharge diffusers as shown in Figure 2. The transition piece
must not have an angle greater than 30
performance can result. Do not connect the full duct size to
the unit without using a transition piece down to the size of
the discharge collar on the unit. With metal duct material, the
sides only of the elbow and entire branch duct should be
internally lined with acoustic insulation for sound attenuation. Glass fiber duct board material is more absorbing and
may permit omission of the flexible connector.
The ductwork should be laid out so that there is no line of
sight between the conditioner discharge and the distribution
diffusers.
Return air ducts can be brought in through a wall grille and
then to the unit. The return duct system will normally consist
of a flexible connector at the unit and a trunk duct to the
return air grille. With metal duct material, the return air duct
should be internally lined with acoustic insulation for sound
attenuation. Glass fiber duct board material is more absorbing and may permit omission of the flexible connector.
Return air ductwork to the unit requires the optional return
air duct collar/2" (51mm) filter rack kit. See Figure 3. The kit
can be installed for face side or bottom filter removal. The
flexible connector can then be attached to the 1" (25mm)
duct collar.
Do not use sheet metal screws directly into the unit
cabinet for connection of supply or return air ductwork,
especially return air ductwork which can puncture the drain
pan or the air coil.
o
or severe loss of air
Figure 2.
Trunk Duct
Square Elbow
(Both Sides
Internally Lined
With Acoustic
Insulation)
Branch Duct
(Internally
Lined)
Duct
Transition
Canvas
Collar
Discharge Collar
(on Heat Pump)
Heat Pump
2 ft. x 2 ft
Diffuser
Ventilation air
Outside air may be required for ventilation. The temperature
of the ventilation air must be controlled so that mixture of
outside air and return air entering the conditioner does not
exceed application limits. It is also general practice to close
off the ventilation air system during unoccupied periods
(night setback).
The ventilation air system is generally a separate building
subsystem with distribution ductwork. Simple introduction
of the outside air into each return air plenum chamber
reasonably close to the conditioner air inlet is not only
adequate, but recommended. Do not duct outside air directly
to the conditioner inlet. Provide sufficient distance for thorough mixing of outside and return air. See “Operating limits”
on page 7.
Figure 3.
Sizes 007 thru 042Sizes 048 & 060
Page 4 / IM 407
Page 5
Electrical Data
General
1. Be sure the available power is the same voltage and phase
as that shown on the unit serial plate. Line and low voltage
wiring must be done in accordance with local codes or the
National Electrical Code, whichever is applicable.
2. Apply correct line voltage to the unit. A 7⁄8" (22mm) or 11⁄8"
(29mm) hole is supplied on the side of the unit. A disconnect switch near the unit is required by code. Power to the
unit must be sized correctly and have time delay (dual
element) fuses or an HACR circuit breaker for branch
circuit overcurrent protection. See the nameplate for
correct ratings.
230 Volt operation and 50 cycle units
All 208-230 volt single and three-phase units are factory
wired for 208 volt operation. For 230 volt operation, the line
voltage tap on the 24 volt transformer must be changed.
Figure 4A.Figure 4B.
Disconnect and cap the red lead wire and interchange it with
the orange lead wire on the primary of the 24 volt transformer. Three-phase 50 cycle units require a neutral wire for
230/50/1 power.
Fan speed change
All units have two-speed fan motors and are shipped for
high speed operation. On unit sizes 007, 009 and 012, the
change from high speed to low speed is done by removing
the black wire from the fan relay and connecting the red wire
to the fan relay (Figure 4A). On units sizes 015 through 060,
each fan motor is supplied with a 5-pin terminal block
mounted on the fan motor. To change from high speed to
low speed, move the wire from the black #3 location to the
red #4 location on unit sizes 015 through 042 or to the red
#5 location on units sizes 048 and 060. On 575 volt units,
add a jumper between black #3 and blue #4 for low speed
operation. See Figure 4B.
COMMON (WHITE)
FAN
MOTOR
BROWN (CAPACITOR)
BLACK (HIGH SPEED)
RED (LOW SPEED)
Piping
1. All units are recommended to be connected to supply
and return piping in a two-pipe reverse return configuration. A reverse return system is inherently self-balancing
and requires only trim balancing where multiple quantities of units with different flow and pressure drop characteristics are connected to the same loop. A simple
way to check for proper water balance is to take a
differential temperature reading across the water connections. To insure proper water flow, the differential
should be 10
A direct return system may also be made to work acceptably, but proper water flow balancing is more difficult to achieve and maintain.
2. The piping can be steel, copper or PVC.
3. Supply and return runouts are usually connected to the
unit by short lengths of high pressure flexible hose which
are sound attenuators for both unit operating noise and
hydraulic pumping noise. One end of the hose should
have a swivel fitting to facilitate removal for service. Hard
piping can also be brought directly to the unit although
it is not recommended since no vibration or noise attenuation can be accomplished. The hard piping must
have unions to facilitate unit removal. See Figure 5 for
typical piping setup.
4. Supply and return shutoff valves are required at each
conditioner. The return valve is used for balancing and
should have a “memory stop” so that it can always be
closed off but can only be reopened to the proper
o
F (5oC) to 14oF (8oC).
COMMON
CAPACITOR
HIGH SPEED
LOW SPEED
LOW SPEED
FAN
MOTOR
YELLOW 1
BROWN 2
BLACK 3
*RED 4
*RED 5
*On unit sizes 048 and 060, terminal 4 is colorcoded blue and terminal 5 is color-coded red.
JUMPER
position for the flow required.
5. No unit should be connected to the supply and return
piping until the water system has been cleaned and
flushed completely. After the cleaning and flushing has
taken place, the initial connection should have all valves
wide open in preparation for water system flushing.
6. Condensate piping can be steel, copper or PVC. Each
unit is supplied with a
7
⁄8" (22mm) ODM copper stub.
7. The condensate disposal piping must have a trap and
the piping must be pitched away from the unit not less
1
⁄4" inch per foot (21mm per meter). Generally, the
than
condensate trap is made of copper and soldered on the
unit. See Figure 6. A piece of vinyl hose from the trap to
the drain line is used for simple removal. A complete
copper or PVC condensate system can also be used.
Union fittings in the copper lines should be applied to
facilitate removal. Factory supplied condensate hose
assemblies have a
7
⁄8" (22mm) sweat to FPT fitting to
facilitate connection of a flexible vinyl, rubber or steel
braided hose.
8. No point in the drain system may be above the drain
connection of any unit.
9. Automatic flow controlled devices must not be installed
prior to system cleaning and flushing.
10. A high point of the piping system must be vented.
11. Check local code for the need for dielectric fittings.
IM 407 / Page 5
Page 6
Figure 5.Figure 6.
Balancing
Blower
Motor
Access
Flexible Hose
With Brass
Pipe Fitting
Electrical &
Compressor
Access
Isolator Pad
Note: Condensate drain connection must be minimum of 1" (25mm)
below connection to heat pump.
Note: Do not overtorque fittings. The maximum torque without damage to fittings is 30 foot pounds. If a torque wrench is not available, use as a rule of thumb,
finger-tight plus one quarter turn. Use two wrenches to tighten the union, one to hold the line and one for simultaneous tightening of the nut.
Valve With
Close-off
Supply
Return
Condensate
1
1
(38mm)
⁄2"
Electrical Access Panel
1
⁄2"
1
(38mm)
Optional Cleanout
1
⁄4'' Per Foot
(21mm Per Meter)
Cleaning and Flushing System
1. Prior to first operation of any conditioner, the water circulating system must be cleaned and flushed of all construction dirt and debris.
If the conditioners are equipped with water shutoff
valves, either electric or pressure operated, the supply
and return runouts must be connected together at each
conditioner location. This will prevent the introduction of
dirt into the unit. Additionally, pressure operated valves
only open when the compressor is operating.
Figure 7.
Return Runout
Supply Runout
Mains
Rubber Hose
Runouts Initially
Connected Together
2. The system should be filled at the city water makeup connection with all air vents open. After filling, vents should be
closed.
The contractor should start main circulator with pressure reducing valve makeup open. Vents should be
checked in sequence to bleed off any trapped air to
assure circulation through all components of the system.
Power to the heat rejector unit should be off, and the
supplementary heat control set at 80
o
F (27oC).
While circulating water, the contractor should check
and repair any leaks in the piping. Drains at the lowest
point(s) in the system should be opened for initial flush
and blow-down, making sure city water fill valves are set
to make up water at the same rate. Check the pressure
gauge at pump suction and manually adjust the makeup
to hold the same positive steady pressure both before and
after opening the drain valves. Flush should continue for
at least two hours, or longer if required, to see clear, clean
drain water.
3. Supplemental heater and circulator pump should be shut
off. All drains and vents should be opened to completely
drain down the system. Short circuited supply and return
runouts should now be connected to the conditioner
supply and return connections. Teflon tape is recommended over pipe dope for pipe thread connections. Use
no sealers at the swivel flare connections of hoses.
4. Trisodium phosphate was formerly recommended as a
cleaning agent during flushing. However, many states
and localities ban the introduction of phosphates into
their sewage systems. The current recommendation is to
simply flush longer with warm 80
o
F (27oC) water.
5. Refill the system with clean water. Test the litmus paper
for acidity, and treat as required to leave the water slightly
alkaline (pH 7.5 to 8.5). The specified percentage of
antifreeze may also be added at this time. Use commercial grade antifreeze designed for HVAC systems only. Do
not use automotive grade antifreeze.
6. Set the system control and alarm panel heat add setpoint
o
to 70
F (21oC) and the heat rejection setpoint to 85oF
o
C). Supply power to all motors and start the circulating
(29
pumps. After full flow has been established through all
components including the heat rejector (regardless of
season) and air vented and loop temperatures stabilized,
each of the conditioners will be ready for check, test and
start-up and for air and water balancing.
Start-up
1. Open all valves to full open position and turn on power
to the conditioners.
2. Set thermostat for “Fan Only” operation by selecting
“Off” at the system switch and “On” at the fan switch. If
“Auto” fan operation were selected, the fan would cycle
with the compressor. Check for proper air delivery.
Page 6 / IM 407
3. All units have two-speed motors. Reconnect for low
speed operation if necessary.
4. Set thermostat to “Cool.” If the thermostat is an automatic changeover type, simply set the cooling temperature to the coolest position. On manual changeover
types additionally select “Cool” at the system switch.
Page 7
Again, many conditioners have time delays which
protect the compressor against short cycling. After a
few minutes of operation, check the discharge grilles for
cool air delivery. Measure the temperature difference
between entering and leaving water. It should be approximately 1
temperature difference. For example, if the cooling temperature difference is 15
ture difference should have been 12
Without automatic flow control valves, a cooling
temperature difference of 10
1
⁄2 times greater than the heating mode
o
F (8oC), the heating tempera-
o
F (5oC).
o
F to 14oF (5oC to 8oC) is
about right. Adjust the combination shutoff/balancing
valve in the return line to a water flow rate which will
result in the 10
o
F to 14oF (5oC to 8oC) difference.
5. Set thermostat to “Heat.” If thermostat is the automatic
changeover type, set system switch to the “Auto” position and depress the heat setting to the warmest selection. Some conditioners have built-in time delays which
prevent the compressor from immediately starting. With
most control schemes, the fan will start immediately.
After a few minutes of compressor operation, check for
warm air delivery at discharge grille. If this is a “cold
building” start-up, leave unit running until return air to
the unit is at least 65
o
F (18oC).
Measure the temperature difference between entering and leaving air and entering and leaving water. With
entering water of 60
water should be 6
o
F to 80oF (16oC to 27oC), leaving
o
F to 12oF (3.3oC to 6.7oC) cooler, and
the air temperature rise through the machine should not
exceed 35oF (19oC). If the air temperature exceeds 35oF
o
(19
C), the airflow rate is probably inadequate.
If the water temperature difference is less than 6
o
(3.3
C), the water flow rate is excessive. If the water
temperature difference exceeds 12
o
F (6.7oC), then the
o
water flow rate is inadequate.
6. Check the elevation and cleanliness of the condensate
line. If the air is too dry for sufficient dehumidification,
slowly pour enough water into the condensate pan to
ensure proper drainage.
7. If the conditioner does not operate, the following points
should be checked:
a. Is proper voltage being supplied to the machine?
b. Is the proper type of thermostat being used?
c. Is the wiring to the thermostat correct?
8. If the conditioner operates but stops after a brief period,
check for:
a. Is there proper airflow? Check for dirty filter, incorrect
fan rotation (3-phase fan motors only), or incorrect
ductwork.
b. Is there proper water flow rate within temperature
limits? Check water balancing; backflush unit if dirt
clogged.
9. Check the unit for vibrating refrigerant piping, fan wheels,
etc.
10. Do not lubricate the fan motor during the first year of
operation as it is prelubricated at the factory.
F
Operating Limits
Environment
This equipment is designed for indoor installation only.
Sheltered locations such as attics, garages, etc., generally
will not provide sufficient protection against extremes in
temperature and/or humidity, and equipment performance,
reliability, and service life may be adversely affected.
Power supply
A voltage variation of ±10% of nameplate utilization voltage
is acceptable. Three-phase system unbalance shall not exceed 2%.
Note: Voltages listed are to show voltage range. However,
units operating with overvoltage and undervoltage for extended periods of time will experience premature component
failure.
Additional information
1. Standard units — Units are designed to start and operate
in an ambient of 40
with entering water at 70
at the flow rates used in the ARI Standard 320-86 rating
test, for initial start-up in winter.
Note: This is not a normal or continuous operating con-
dition. It is assumed that such a start-up is for the purpose
of bringing the building space up to occupancy temperature.
o
F (5oC), with entering air at 40oF (5oC),
o
F (21oC), with both air and water
2. Extended range units— Extended range heat pump
conditioners are designed to start and operate in an
ambient of 40
entering water at 40
o
F (5oC), with entering air at 40oF (5oC), with
o
F (5oC), with both air and water at the
flow rates used in the ARI Standard 320-86 rating test, for
initial start-up in winter.
Note: This is not a normal or continuous operating con-
dition. It is assumed that such a start-up is for the purpose
of bringing the building space up to occupancy temperature.
Air and water limits
STANDARDEXTENDED
UNITSRANGE UNITS
CoolingHeatingCoolingHeating
Min. Amb. Air50oF/10oC50oF/10oC40oF/5oC40oF/5oC
Normal Amb. Air80oF/27oC70oF/21oC80oF/27oC70oF/21oC
Max. Amb. Air100oF/38oC85oF/29oC 100oF/38oC85oF/29oC
Min. Ent. Air ➀ ➁50oF/10oC50oF/10oC50oF/10oC40oF/5oC
Normal Ent. Air,80/67
db/wb27/19oC21oC27/19oC21oC
Max. Ent. Air,100/83
db/wb ➀ ➁38/28oC27oC38/28oC27oC
o
F70oF80/67oF70oF
o
F80oF100/83oF80oF
Water enthalpy
Min. Ent. Water
➀ ➁
Normal Ent. Water 85oF/29oC70oF/21oC85oF/29oC70oF/21oC
Max. Ent. Air,
➀ ➁
➀ At ARI flow rate
➁ Maximum and minimum values may not be combined. If one value is at
maximum or minimum, the other two conditions may not exceed the
normal condition for standard units. Extended range units may combine
any two maximum or minimum conditions, but not more than two, with all
other conditions being normal conditions.
CoolingHeatingCoolingHeating
o
F/13oC55oF/13oC40oF/5oC40oF/5oC
55
o
F/43oC90oF/32oC 110oF/43oC90oF/32oC
110
IM 407 / Page 7
Page 8
60 Cycle Wiring Diagrams — Mark IV/AC Units
Figure 8. Unit sizes 007 through 012 (208-230, 265 volts, single-phase) 060686404 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Unit is factory wired for 230V operation. If 230V power supply is
used, transformer must be rewired by disconnecting the power
from the red transformer primary wire and connecting the power
lead to the orange transformer primary wire. Place an insulation
cap on the red transformer primary wire.
3. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
4. All temperature and pressure switches are normally closed.
5. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 9. Unit size 015 (208-230, 265 volts, single-phase) 060856804 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Unit is factory wired for 230V operation. If 230V power supply is
used, transformer must be rewired by disconnecting the power
from the red transformer primary wire and connecting the power
lead to the orange transformer primary wire. Place an insulation
cap on the red transformer primary wire.
3. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
4. All temperature and pressure switches are normally closed.
5. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Page 8 / IM 407
Page 9
Figure 10. Unit sizes 019 through 048 (208-230, 265 volts, single-phase) 060686606 Rev. C
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Unit is factory wired for 230V operation. If 230V power supply is
used, transformer must be rewired by disconnecting the power
from the red transformer primary wire and connecting the power
lead to the orange transformer primary wire. Place an insulation
cap on the red transformer primary wire.
3. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
4. All temperature and pressure switches are normally closed.
5. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 11. Unit sizes 060 (208-230 volts, single-phase) 063393303 Rev. C
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Unit is factory wired for 230V operation. If 230V power supply is
used, transformer must be rewired by disconnecting the power
from the red transformer primary wire and connecting the power
lead to the orange transformer primary wire. Place an insulation
cap on the red transformer primary wire.
3. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
4. All temperature and pressure switches are normally closed.
5. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
IM 407 / Page 9
Page 10
Figure 12. Unit sizes 024 through 060 (208-230 volts, three-phase) 060686704 Rev. B
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Unit is factory wired for 230V operation. If 230V power supply is
used, transformer must be rewired by disconnecting the power
from the red transformer primary wire and connecting the power
lead to the orange transformer primary wire. Place an insulation
cap on the red transformer primary wire.
3. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
4. All temperature and pressure switches are normally closed.
5. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 13. Unit sizes 024 through 060 (460 and 575 volts, three-phase) 060686804 Rev. B
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Page 10 / IM 407
Page 11
50 Cycle Wiring Diagrams — Mark IV/AC Units
Figure 14. Unit sizes 007 through 012 (230 volts, single-phase) 061415316 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 15. Unit sizes 015 through 019 (230 volts, single-phase) 061415318 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
IM 407 / Page 11
Page 12
Figure 16. Unit sizes 024 (230 volts, single-phase) 061415320 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 17. Unit sizes 048 and 060 (230 volts, single-phase) 063393303 Rev. C
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Page 12 / IM 407
Page 13
Figure 18. Unit sizes 024 through 042 (380 volts, three-phase) 061415321 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
Figure 19. Unit sizes 048 and 060 (380 volts, three-phase) 061415322 Rev. A
Notes:
1. Mark IV/AC controller board contains a static sensitive microprocessor. Proper grounding of field service personnel is required or
damage to controller may result.
2. Terminal block on Mark IV/AC board provides 24 VAC at terminals R and C. All other terminals are 24 VDC output.
3. All temperature and pressure switches are normally closed.
4. Field supplied relays attached to the 24 volt terminals R, W, Y or
G may introduce electrical noise. Never install relays in series
with the inputs.
IM 407 / Page 13
Page 14
Unit Operation
General
Each unit has a printed circuit board control system. The low
voltage output from the low voltage terminal strip on the
control board is always 24 volts DC (direct current). Terminals R and C on the low voltage terminal strip supply 24 volts
AC power. The unit has been designed for operation with a
24 volt mercury bulb type wall thermostat or a microelectronic wall thermostat selected by the manufacturer. Do not
operate the unit with any other type of wall thermostat.
Two types of units are available: electromechanical control units or Mark IV/AC control units. Both have 24 volt DC
circuits on the output of the low voltage terminal strip. Each
requires its own unique automatic changeover thermostat.
Mark IV/AC control units
The Mark IV/AC circuit board is an optional control system
with built-in features such as random start, compressor time
delay, night setback, load shed, shutdown, condensate
overflow protection, defrost cycle, brownout, and LED/fault
outputs. Figure 28 shows the LED and fault output sequences.
The 24 volt low voltage terminal strip is set up so R-G
energizes the fan, R-Y1 energizes the compressor for cooling operation, R-W1 energizes the compressor and reversing
valve for heating operation. The reversing valve is set up to
be energized in the heating mode. The circuit board has a fan
interlock circuit to energize the fan whenever the compressor
is on if the thermostat logic fails to do so.
The Mark IV/AC control board has a lockout circuit to stop
compressor operation if any one of its safety switches opens
(high pressure switch and low pressure switch on unit sizes
048 and 060). If the low temperature switch opens, the unit
will go into the cooling mode for 60 seconds to defrost any
slush in the water-to-refrigerant heat exchanger. After 60
seconds the compressor is locked out. If the condensate
sensor detects a filled drain pan, the compressor operation
will be suspended only in the cooling mode. The unit is reset
by opening and closing the disconnect switch on the main
power supply to the unit in the event the unit compressor
operation has been suspended due to low temperature
(freezestat) switch, high pressure switch, or low pressure
switch on unit sizes 048 and 060. The unit does not have to
be reset on a condensate overflow detection.
The Mark IV/AC control circuit has a fault output signal to
an LED on a wall thermostat. Figure 28 shows for which
functions the fault output is “on” (sending a signal to the
LED).
The Mark IV/AC control circuit has built-in night setback
operation. A “grounded” signal to the “U” terminal on the low
voltage terminal strip puts the unit into the unoccupied mode
for night setback operation. The fan shuts off and the unit is
put under control from the night setback terminal on the
thermostat, W2; day heating and cooling operation is locked
out. R-W2 energizes the compressor and reversing valve for
Figure 28.
INDICATION
Normal modeOffOnOffOff
High pressure faultOffOffFlashOn
* Low temperature faultFlashOffOffOn
Condensate overflowOnDimOffOn
BrownoutOffFlashOffOn
Load shedOffOffOnOff
Unoccupied modeOnOnOffOff
Unit shutdownOffFlashOffOn
YELLOW GREENREDOUTPUT
LEDSFAULT
* In heating mode only.
Figure 29.
Unit #1Unit #2
Time Clock
To activate the unoccupied mode for units on the same clock schedule, a single wire can be
“daisy-chained” between units and simply grounded through the time clock contacts. The
same system can also be done to activate the load shed and emergency shutdown modes
by running additional wires between units to ground.
Unit #3
Ground
To
Additional
Units
heating operation. Night setback operation can be overridden for two hours by toggling the fan switch (intermittently
closing the R to O terminals) on the Deluxe Auto Changeover
thermostat. Day thermostat setpoints the control the heating
and cooling operation. The Mark IV/AC control system is also
set up for load shed and shutdown operation on receipt of a
“grounded” signal to the “L” and “E” terminals, respectively,
on the low voltage terminal strip. See Figure 29.
The P and C terminals of the Mark IV/AC board are used
for pump restart. These terminals pass a voltage signal
whenever the unit compressor is turned on. This signal is
detected by a pump restart relay board providing an N.O. or
N.C. set of contacts for heat pump loop circulation pump
control. When used with the Loop Water Controller, the relay
operation accommodates turning off circulation pump control. When used with the Loop Water Controller, the relay
operation accommodates turning off circulation pumps during unoccupied periods with a safety override dependent on,
at minimum, one WSHP's need. The P and C terminals may
be “daisy-chained” between 200 units. See page 19.
*in heating mode only
Note: The fault output is energized when no faults exist. The fault output is
de-energized during faults and when unit power is off.
General Use and Information
The Mark IV/AC control board is provided with three drive terminals,
R(24vac), F(24vdc), and C(Ovac) that can be used by the end user to
drive the thermostat inputs (G, Y1, W1, and W2) and control inputs
(U, L, E, and O). Any combination of a single board drive terminal (R,
F, or C) may be used to operate the Mark IV/AC boards control or
thermostat inputs. However, only one drive terminal (R, F, or C) can
be connected to any individual input terminal or damage will occur.
Some of the control inputs are used within the Water Source Heat
Pump and not accessible to the end user. For example, HP, LT, and
COF are not available for use by the end user.
Typically the Mark IV/AC board’s R(24vac) terminal is used to drive
the board’s thermostat inputs and control inputs by connecting it to
the R terminal of an industry standard thermostat. The control
outputs of the standard thermostat are then connected to the Mark
IV/AC board thermostat inputs and control inputs as needed. Any
remaining board input(s) may be operated by additional thermostat
outputs or remote relays (dry contacts only).
All Mark IV/AC board inputs must be operated by dry contacts
powered by the control board’s power terminals. No solid state
devices (Triacs) may be used to operate Mark IV/AC board inputs.
No outside power sources may be used to operate Mark IV/AC
board inputs.
Using DriveUsing DriveUsing Drive
Terminal R (24vac) Terminal F (vdc)Terminal C (ground)
Note: Thermostat provides a fixed 13oF differential between W1 and W2.
P/N 105571003 Includes Thermostat and Subbase
(Honeywell P/N’s T874C1869 and Q674C1579)
Fan Switch: Auto / On / Tenant Override
System Switch: Off / Auto
Time Clock
(by others)
Daisy-chain connection to
additional units Mark IV/AC
board “U” terminals
Operation: The units Mark IV/AC board
will be in the occupied mode, monitoring
terminals W1 and Y1 and ignoring
terminal W2, when the time clock
contacts are open. The Mark IV/AC
board will be in the unoccupied mode,
monitoring terminal W2 and ignoring
terminals W1 and Y1, when the time
clock contacts are closed. No cooling is
allowed during the unoccupied mode.
The tenant override feature of the
thermostat allows the occupant to force
a 2-hour override of unoccupied mode.
During this override period the W1 and
Y1 terminals are monitored and the W2
terminal is ignored (same as occupied).
Page 16 / IM 407
GW1Y1 RRc C
Thermostat Terminals
P/N 105570801
Includes Thermostat and Wall Plate
(Honeywell P/N T8524D1064)
The multiple unit control board is an accessory used when
you need to control up to 3-units from a single thermostat.
The board is typically mounted in the unit control box
closest to the thermostat. A maximum of 2 boards may be
used together if up to 6-units must be connected and
controlled from a single thermostat.
This version of the board uses VAC relays and should not be
used in combination with any other accessories or equipment that require VDC connections to the "G", "W1", or
"Y1" terminals (i.e. Boilerless System Kit).
The multiple unit control board provides the components
necessary to protect the Mark IV/AC board from electrical
damage that may occur when using standard off-the-shelf
relays.
Multiple Unit
Control Panel
GWY R C
GW1Y1RRc C
Thermostat Terminals
TB4
TB3
TB2
TB1
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
R
Y
G
W
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
R
Y
G
W
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
R
Y
G
W
Up to 2 Units (Part No. 106059801)
The multiple unit control board is an accessory used when
you need to control up to 2-units from a single thermostat.
The board is typically mounted in the unit control box
closest to the thermostat. The "G", "W", "Y", "C", and "L"
connections are short flying leads pre-attached to the
board. A maximum of 3 boards may be used together if up
to 4-units must be connected and controlled from a single
thermostat.
This version of the board uses VDC relays and should not
be used in combination with any other accessories or
equipment that require VAC Connections to the "G", "W1"
or "Y1" terminals (i.e. Boilerless System Kit). Do not use the
unoccupied (U-terminal) feature with the multiple unit control board.
The multiple unit control board provides the components
necessary to protect the Mark IV/AC board from electrical
damage that may occur when using standard off-the-shelf
relays.
Multiple Unit
Control
Panel
GWY C L
GW1Y1 R Rc C
Thermostat Terminals
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
R
Y
G
W
L
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
IM 407 / Page 17
Page 18
Motorized Valve & Relay for Unit Sizes 007 to 060
Wired as shown below the motorized valve will open on
a call for compressor operation. Valves for unit sizes
007 to 019 are 1⁄2˝ power-open spring-return while unit
sizes 024 to 060 are 3⁄4˝ power-open power-close. Other
thermostat combinations may be used. Valve and
auxiliary relay are purchased separately.
Note: The wiring shown below can only be used when the “P” terminal
is not being used as a pump restart signal to other equipment. If the
“P” terminal must be used as a pump restart signal to other equipment,
then wire the auxiliary relay’s yellow wire to “Y1”, white wire to “W1”,
and orange wire to “C”, then the valve will open on a call for occupied
Note: Thermostat provides a fixed 13oF differential between W1 and W2.
Options on Mark IV/AC Units
Auxilliary Relay (P/N 106059701)
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
Operation: In this example the
auxiliary relay contacts can be
used to indicate a fault
condition. With the auxiliary
relay connected as shown, the
normally open contacts will
close during a fault condition.
1
2
3
Auxiliary Relay
Orange
Yellow
White
OW2GW1Y1 FELU AP V R C
OW2GW1Y1 A R
Thermostat Terminals
P/N 105571003
Includes Thermostat and Subbase
(Honeywell P/N’s T874C1869 and Q674C1579)
Fan Switch: Auto / On / Tenant Override
System Switch: Off / Auto
The auxiliary relay is designed to interface external equipment
with the Mark IV/AC board. The auxiliary relay has been provided with the components necessary to protect from electrical
damage that may occur to the Mark IV/AC board when using
standard off-the-self relays. The auxiliary relay can be used to
provide fault signals, unit operation signals, or to provide a
means for remote equipment to control the Mark IV/AC board.
The orange, yellow, and white connections are short flying leads
pre-attached to the board. The diagrams shown are some
connection examples.
Time Clock
(by others)
Daisy-chain to
additional Mark IV/AC
board “U” terminals
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
Operation: In this example the
auxiliary relay contacts can be
used to signal WSHP fan
operation to another device. In
this example when the
thermostat energizes the “G”
terminal the auxiliary relay
normally open contacts will
close.
1
2
3
Auxiliary Relay
Orange
Yellow
White
Page 18 / IM 407
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 F E L U A P V R C
1
2
3
Auxiliary Relay
Orange
Yellow
White
Operation: In this example the
auxiliary relay is used to
interface other control devices
to the Mark IV/AC board. Using
the Orange (-) and White (+)
wires, and 24vac or 24vdc,
another device could be used
to start and stop the WSHP
heating sequence.
Page 19
6.5 (165 mm) (007 – 042)
4.12 (105 mm) (048 – 060)
Boilerless System Kit (BSK)
P/N 062522201 for Sizes 007 to 042
P/N 062522204 for Sizes 048 to 060
The BSK option for use with the Mark IV/AC control board
provides the capability to control a remote duct heater. The
duct heater must be provided with a low voltage control
circuit that only requires a set of dry contacts for operation.
The contacts shown on the Boilerless System board (termi-
9.66
(245 mm)
(007 – 042)
14.50
(368 mm)
(048 – 060)
1.75
(44.5 mm)
Wire Ends to be Field
Connected to the
Mark IV/AC Board
RD
RD
nals 1, 2, and 3) are used to control the remote duct heater,
the N.O. contacts will close on a call for duct heater heat.
POT1 provides a means to manually adjust the water temperature setpoint (adjustment range is 43
Normal/Override switch provides a means to manually force
electric heat to always be used in place of heat pump heat
when in the override position (default position is normal - heat
pump heat).
When the water temperature drops below the value of POT1,
then the duct heater will be used instead of heat pump heat
on a call for heat from the low voltage thermostat (not
included).
OR
43 Ohm
BR
WH
WH
1
2
3
Auxiliary Relay
WH
YE
WSHP Mark IV/AC Board Low Voltage Terminal Strip
4-pin
Plug
OR
GRGR
Orange
Yellow
White
RD
WH
BK
Boilerless
System
Board
OR
Normal
Pot 1
Override
O
F to 60OF). The
Water
Temperature
Sensor
12345
Signal to remote
duct heater
control circuit
The BSK field installed kits include the sheet metal enclosure
with cover, wire harness, boilerless system board, auxiliary
relay, and water temperature sensor. When used, one BSK is
required for each unit. To use the BSK kit you attach the sheet
metal enclosure to the unit as shown, route the 4-wire
harness through knockouts and connect to the Mark IV/AC
board, mount and connect and insulate the water temperature sensor on the water supply line, and then connect the
duct heater control contacts to the duct heater control
circuit.
Wire ends
from
Boilerless
System Kit
WSHP Mark IV/AC Board
Low Voltage Terminal Strip
OR
BR
RD
43 Ohm
WH
0W2 GW1Y1 F E L U A P VR C 0W2 G W1Y1FE L U A P V R C
GW1Y1 W2 Y2 R Rc C
Thermostat Terminals
+
R1
If night setback (U-terminal) is used, the duct heater will
respond to the occupied W1 thermostat signal. The load
shed input (L-terminal) cannot be used for other control
functions when being used with the BSK.
The BSK is a DC voltage device, when the BSK is used the
thermostat must be wired for VDC operation, one example is
provided below. This example is for a 2-circuit WSHP, R1 is
a field supplied 24vdc relay. R1 is not required on 1-circuit
units.
R1
WSHP Mark IV/AC Board
Low Voltage Terminal Strip
IM 407 / Page 19
Page 20
Pump Restart Relay Kit P/N 061419001
Used as an option with the Mark IV/AC board, the pump
restart relay kit provides a means to alert the loop water
controller that water flow is required by a WSHP so that the
system pump can be started. This option is typically used in
installations where the pump may be shut off when there is
no need for water flow (i.e. temperature OK, etc.). Typically
only one pump restart relay kit is required per installation as
up to 200 Mark IV/AC boards can be “daisy-chained” together.
The Mark IV/AC “P” terminal is used to determine WSHP
compressor operation. Wired as shown below, when compressor operation is required, the Mark IV/AC “P” terminal
will change state causing a contact closure between terminal
58 and 64 signaling the loop water control (LWC) panel to
restart the loop pump if Off.
The pump restart relay kit is typically mounted within one
WSHP or within the LWC panel, whichever is more convenient, diagrams are provided below for each location. To
install the relay, remove the cover on the double-faced tape
provided on the relay and attach the relay either to the inside
of the LWC panel (adjacent to circuit breaker CB1 and
terminal block TB3) or in the WSHP control box (in a convenient location), then wire as shown below.
Wiring Pump Restart Relay when Installed within the LWC Panel
WSHP Mark IV/AC Board Low Voltage Terminal Strip
OW2GW1Y1 FELUAPVRC
Pump
Restart
Relay
7
6
5
4
3
64
58
Daisy chain to other Mark
IV/AC board “P” and “C”
terminals
Loop
Water
Controller
Terminals
2
1
65
Wiring Pump Restart Relay when Installed within a WSHP Control Box
WSHP Mark IV/AC Board Low Voltage Terminal Strip (Circuit 1)
OW2GW1Y1 FELUAP VRC
Daisy chain to other Mark
IV/AC board “P” and “C”
terminals
64
58
Controller
Terminals
Loop
Water
Pump
Restart
Relay
7
6
5
4
3
2
1
Page 20 / IM 407
Page 21
WARNING
!
Troubleshooting Water Source Heat Pump
To avoid electrical shock, personal injury or death, be sure that field wiring complies with local and national fire, safety, and electrical
codes, and voltage to the system is within the limits shown in the job-specific drawings and unit electrical data plate(s).
Power supply to unit must be disconnected when making field connections. To avoid electrical shock, personal injury or death, be sure
to rigorously adhere to field wiring procedures regarding proper lockout and tagout of components.
Low Voltage, check power
supply voltage
Check wiring - loose or broken
and check for bad
connection
Check relays and contacts,
also capacitor and wiring
Check high pressure switch
and low temperature switch to
see if unit is cycling on the safety
Check to see if the reversing
valve is not hung up and is
operating correctly
Check condensate overflow
switch in cool mode of operation
Fuse may be blown, circuit
breaker is open
Fan, nor Compressor Run
Compressor runs
in short cycle
Compressor attempts to start
but doesn’t
Wires may be loose or broken.
Replace or retighten wires
Fan operates,
Unit
Insufficient cooling or heating
Compressor does not
Unit Control, check thermostat
for correct wiring or bad t’stat
Check capacitor
Check wiring - loose or broken
and check for bad
connection
Hi pressure lockout A. Cool mode, check water flow
B. Heating mode, check air flow
C. Check reversing valve for
proper valve position
Check compressor overload
make sure it’s closed
Check compressor to ground,
or for internal short to ground.
Compressor winding may be
open. Check continuity with
ohm meter
Check compressor wiring for
defective wiring or loose
connection
Check for defective compressor
internal windings with ohm meter
Check for bad compressor
capacitor
Check for lock rotor amp draw
Check themostat for improper
location
Check for proper air flow. Filter
could be dirty
Check blower assembly for
dirt or bad fan motor capacity
Check for low refrigerant charge
Check amp draw on blower
assembly
IM 407 / Page 21
Page 22
Maintenance
1. Normal maintenance on all conditioners is generally limited to filter changes. Lubrication of the fan motor is not
required but may be performed to extend motor life. Use
SAE-20 nondetergent electric motor oil.
2. Filter changes are required at regular intervals. The time
period between changes will depend upon the project
requirements. Some applications such as motels produce a lot of lint from carpeting and linen changes, and
will require more frequent filter changes. It is suggested
that the filter be checked at 60-day intervals for the first
year until experience is acquired. If light cannot be seen
through the filter when held up to sunlight or a bright light,
it should be changed. A more critical standard may be
desirable.
3. The condensate drain pan should be checked annually
and cleaned and flushed as required.
4. Recording of performance measurements of volts, amps,
and water temperature differences (both heating and
cooling) is recommended. A comparison of logged data
with start-up and other annual data is useful as an indicator of general equipment condition.
5. Periodic lockouts always are caused by air or water
problems. The lockout (shutdown) of the conditioner is a
normal protective result. Check for dirt in the water
system, water flow rates, water temperatures, airflow
rates (filter may be dirty), and air temperatures. If the
lockout occurs in the morning following a return from
night setback, entering air below machine limits may be
the cause.
Page 22 / IM 407
Page 23
Notes
IM 407 / Page 23
Page 24
This document contains the most current product information as of this printing. For the most up-to-date
product information, please go to www.mcquay.com.