AAON HP2C2 Two Condenser Head Pressure II Module User Guide
- June 15, 2024
- AAON
Table of Contents
AAON HP2C2 Two Condenser Head Pressure II Module
OVERVIEW
Module Overview
Overview
The Two Condenser Head Pressure II Module (ASM01891) monitors four individual
head pressure transducers and controls two Condenser Fans or Water Valves on
units with two physically separate condenser sections. The highest reading of
head pressure transducers 1 & 2 controls Condenser Signal A. The highest
reading of head pressure transducers 3 & 4 controls Condenser Signal B. If
this is a heat pump unit, the module is able to detect when the unit is in
Heat Pump Heating mode and will force the condenser signal to 100% until it
leaves this mode.
The Two Condenser Head Pressure II Module is designed to work stand-alone by
using its OPTIONS dip switch to adjust the Head Pressure setpoint.
The Two Condenser Head Pressure II Module is directly connected to the VCM-X
Modular E-BUS, VCM-X WSHP E-BUS or SA E-BUS Controller, allowing the Module(s)
to receive setpoints from the Controller.
When using the Two Condenser Head Pressure II Module with the RNE Controller,
refer to the RNE Controller Technical Guide.
The Two Condenser Head Pressure II Module also provides a pulse width
modulation (PWM) signal or voltage output signal to control the condenser
fans.
The Two Condenser Head Pressure II Module requires a 24 VAC power connection
with an appropriate VA rating.
Features
The Two Condenser Head Pressure II Module provides the following:
- Can be operated stand alone or up to two modules can be daisy-chained together and connected to a VCM-X Modular E-BUS, VCM-X WSHP E-BUS, or SA E-BUS Controller
- Monitors up to four individual head pressure transducers Provides control of Condenser Output Signals based on the highest reading of head pressure transducers
- Capable of monitoring a Reverse Valve Signal
- Forces Condenser Fans to 100% while in the Heat Pump Heating Mode
NOTE: The Two Condenser Head Pressure II Module contains no user- serviceable parts. Contact qualified technical personnel if your Module is not operating correctly.
NOTE: The HSSC cable is no longer shipped with this module. If it is to be used with a VCM-X Modular E-BUS, VCM-X WSHP E-BUS, or SA E-BU
Figure 1: Two Condenser Head Pressure II Module
INSTALLATION & WIRING
Mounting and Wiring Considerations
Environmental Requirements
The Two Condenser Head Pressure II Module needs to be installed in an
environment that can maintain a temperature range between -30°F and 150°F and
not exceed 90% RH levels (non-condensing).
Mounting
The Two Condenser Head Pressure II Module is housed in a plastic enclosure. It
is designed to be mounted by using the 3 mounting holes in the enclosure base.
It is important to mount the module in a location that is free from extreme
high or low temperatures, moisture, dust, and dirt. Be careful not to damage
the electronic components when mounting the module.
See Figure 2 for Module dimensions (in inches).
WARNING: Be sure all controllers and modules are powered down before
connecting or disconnecting HSSC cables.
Important Wiring Considerations
Please read carefully and apply the following information when wiring the Two Condenser Head Pressure II Module:
- To operate the Two Condenser Head Pressure II Module, you must connect power to the 24 VAC input terminal block.
- Each Pressure Transducer must have its own 18-gauge shielded twisted pair cable. The Drain Wire must be the “Gnd” signal for the transducer.
- When the Analog Output is being used to control the Condenser Fan Speed or Water Valve Percentage, the cable must be 18-gauge shielded wire, and the Drain Wire must be the “Gnd” signal.
- If the Pulse Width Modulation (PWM) Output is being used to directly control the ECM 142 motor, the wires do not need to be shielded and can be any 18-gauge wire.
- Check all wiring leads at the terminal block for tightness.
Be sure that wire strands do not stick out and touch adjacent terminals. Confirm that all transducers required for your system are mounted in the appropriate location and wired into the correct terminals.
Note: All dimensions are in inches
Figure 2: Two Condenser Head Pressure II Module Dimensions
Stand-Alone Wiring
To operate the Two Condenser Head Pressure II Module as Stand Alone, connect
the Module to a 24 VAC connection with an appropriate VA rating. See Figure 3
for wiring.
Check all wiring leads at the terminal block for tightness. Be sure that wire
strands do not stick out and touch adjacent terminals.
Confirm that all transducers required for your system are mounted in the
appropriate location and wired into the correct terminals.
Condenser Type Selection
As shown in Figure 3, set ADDRESS Dip Switch 1 to ON for water cooled or to OFF for air cooled. Refer to page 9 for further instructions.
NOTE : NORMALLY OPEN AND RATED FOR 24 VAC POWER ONLY ALL RELAY OUTPUTS ARE – 1 AMP MAXIMUM LOAD
WARNING!
Observe Polarity! All boards must be wired with GND-to-GND and 24 VAC-to-24
VAC. Failure to observe polarity could result in damage to the boards.
Figure 3: Two Condenser Head Pressure II Module Wiring Diagram (Stand- Alone)
24 VAC Transformer 3 VA Minimum
VCM-X Modular E-BUS, VCM-X WSHP E-BUS or SA E-BUS Controller to Two Condenser Head Pressure II Module Wiring Up to (2) Two Condenser Head Pressure II Modules can be daisy chained together and connected to the E BUS Controller using a modular HSSC cable. The Two Condenser Head Pressure II Module requires a 24 VAC power connection with an appropriate VA rating. See Figure 4 below for wiring Any E-BUS Module can be connected to the E-BUS Controller’s E-BUS port or can be daisy-chained together using HSSC cables.
NOTE: Contact Factory for the correct HSSC cable length for your application. Cables are available in ¼, ½, 1, 2, 3, 4, and 5 Meter lengths and 100 and 150 Foot lengths.
NOTE: NORMALLY OPEN AND RATED FOR 24 VAC POWER ONLY – 1 AMP MAXIMUM LOAD ALL RELAY OUTPUTS
WARNING!!Observe Polarity! All boards must be wired with GND-to-GND and 24
VAC-to-24 VAC.
Failure to observe polarity could result in damage to the boards.
NOTE:
The HSSC cable is no longer shipped with this module.
If it is to be used with a VCM-X Modular E-BUS, VCM-X WSHP E-BUS, or SA E-BUS
Controller, use the existing cable if possible.
Figure 4: VCM-X E-BUS Controller to Two Condenser Head Pressure II Module Wiring Diagram
SEQUENCE OF OPERATION
Stand-Alone Input Commands
General
The following inputs and outputs are available on the Two Condenser Head Pressure II Module. See Table 1 below to reference the Input/Output Map.
Table 1: Two Condenser Head Pressure II Module Inputs & Outputs
Binary Inputs
1| Condenser Fan A On/Off (24 VAC Wet Input)
2| Reversing Valve On/Off (24 VAC Wet Input)
3| Condenser Fan B On/Off (24 VAC Wet Input)
Binary Outputs
1| Condenser A Enable Relay
(Dry Contact Output Rated for 24 VAC)
2| Reversing Valve A Enable
(Dry Contact Output Rated for 24 VAC)
3| Condenser B Enable Relay
(Dry Contact Output Rated for 24 VAC)
4| Reversing Valve B Enable
(Dry Contact Output Rated for 24 VAC)
Analog Inputs
1| Head Pressure #1 (0-667 PSI Sensor)
2| Head Pressure #2 (0-667 PSI Sensor)
3| Head Pressure #3 (0-667 PSI Sensor)
4| Head Pressure #4 (0-667 PSI Sensor)
Analog Outputs (0-10 or 2-10 VDC)
1| Condenser Signal A (AOUT 1)
2| Condenser Signal B (AOUT 2)
PWM Outputs
1| ECM 142 PWM Output (0-100% Duty Cycle)
2| ECM 142 PWM Output (0-100% Duty Cycle)
Stand-Alone Input Commands
Condenser Fan A On/Off
A 24 volt signal to Binary Input #1 initiates the Condenser Fan A Enable
function. Typically, the source for this signal is the “Y” call from the
thermostat calling for a compressor to run.
Reversing Valve On/Off
A 24 volt signal to Binary Input #2 indicates the reversing valve has been
energized and initiates the Reversing Valve Enable On indication function.
Typically, the source for this signal is the “O” call from a thermostat or
other controller.
Condenser Fan B On/Off
A 24 volt signal to Binary Input #3 initiates the Condenser Fan B Enable
function. Typically, the source for this signal is the “Y” call from the
thermostat calling for a compressor to run.
Head Pressure Setpoint
The Head Pressure Setpoint is set using the OPTIONS Dip Switches. See Table 2.
The Default Setpoint for an Air Cooled Condenser is 340 for 410-A refrigerant.
The Default Setpoint for a Water Cooled Condenser is 235 for 410-A
refrigerant. Set the OPTIONS Dip Switch to 0 if using these Default Settings.
See “ADDRESS Dip Switch” below. You must cycle power after setting Dip Switch
values.
NOTE: The only setpoint available for adjustment by the contractor is the
Head Pressure Setpoint.
The rest of the setpoints described can only be changed by the factory.
ADDRESS Dip Switch Settings for Condenser Type Selection
When using the OPTIONS Dip Switch to set the Head Pressure Setpoint, you must
also set the ADDRESS Dip Switch to designate the type of condenser you are
using.
Set ADDRESS Dip Switch 1 to ON for a Water Cooled Condenser or to OFF for an
Air Cooled Condenser.
If set to ON for a Water Cooled Condenser, the Analog Condenser Output Signal
will be 2-10 VDC for the Water Valve. If set to OFF for an Air Cooled
Condenser, the Analog Condenser Output Signal will be 0-10 VDC for the
Condenser Fan.
You must cycle power after setting Dip Switch values. See Figure 3 or
4 for ADDRESS Dip Switch location and Table 3 for Setting information.
SEQUENCE OF OPERATION
VCM-X Input Commands and Modes of Operation
Input Commands (VCM-X Connection)
Condenser A & B On/Off
Instead of a hard wired input signal to the Condenser Enable input, the VCM-X
Modular Controller, VCM-X WSHP Controller, or SA Controller communicates to
the Module via E-BUS communications. This signal indicates the compressor(s)
are called to run and drives the condenser A & B On/Off function.
Reversing Valve Enable A & B On/Off
As with the Condenser Signal On/Off function, the VCM-X Modular Controller,
VCM-X WSHP Controller, or SA Controller communicates to the Module via E-BUS
communications and signals that the reversing valve has been energized and
that heating has been enabled.
NOTE: When the term “ON” is used, it means there is either 24 VAC on the
appropriate Binary Input or a call-to-run signal is being received from a
VCM-X series or SA series controller. When the term “OFF” is used, it means
there is either 0 VAC on the appropriate Binary Input or the call to-run
signal from a VCM-X series or SA series controller has been removed.
Sensor Reading Routine
The Two Condenser Head Pressure Module is used on units with two physically
separate condenser sections. Up to (2) Head Pressure Sensors can be monitored
in each section. The highest of the two readings in each section will be used
to control the condenser fan(s) in that section.
Air from the condenser fan(s) in each section flows through both condenser
coils. As a result, if you modulate the fan(s) based on the highest reading,
you will have enough air flow for both coils.
The highest reading of Head Pressure Sensors 1 & 2 controls Condenser Fan A.
The highest reading of Head Pressure Sensors 3 & 4 controls Condenser Fan B.
Modes of Operation
OFF Mode
The Head Pressure Control Board is in the OFF Mode when the Condenser Input
Signals are “OFF.” In this mode, all relays are off, the Analog Output is 0
VDC, and the PWM Output is 0% Duty Cycle.
Cooling Mode
If the Head Pressure Controller has been configured for the Reversing Valve
to be energized in the Cooling Mode and to Fail to the Heat Mode (Dipswitch 4
is set ON), then the Head Pressure Controller will be in the Cooling Mode when
one or both of the Condenser Signal inputs is “ON” and the Reversing Valve
Enable Signal is “ON”. In this circumstance, the Reversing Valve Enable Relay
Output(s) will energize for indication purposes.
If the Head Pressure Controller has been configured for the Reversing Valve to
be energized in the Heating Mode and to Fail to the Cool Mode (Dipswitch 4 is
set OFF), then the Head Pressure Controller will be in the Cooling Mode when
one or both of the Condenser Signal inputs is “ON” and the Reversing Valve
Enable Signal is “OFF”.
The Condenser Enable Relays will energize to enable the Condenser Fans or
Water Valves. In a water system, the Water Flow Valve will start at 75% for 3
minutes. The Condenser Output Signals will then automatically adjust between 0
and 100% to maintain the desired Head Pressure Setpoint. The Condenser Output
Signals can be a 0-10 VDC, 2-10 VDC or 0-100% PWM signal provided by the
appropriate output. Both outputs mirror each other.
Heating Mode
If the Head Pressure Controller has been configured for the Reversing Valve to
be energized in the Cooling Mode and to Fail to the Heat Mode (Dipswitch 4 is
set ON), then the Head Pressure Controller will be in the Heating Mode when
one or both of the Condenser Signal inputs is “ON” and the Reversing Valve
Enable Signal is “OFF”.
If the Head Pressure Controller has been configured for the Reversing Valve to
be energized in the Heating Mode and to Fail to the Cool Mode (Dipswitch 4 is
set OFF), then the Head Pressure Controller will be in the Cooling Mode when
one or both of the Condenser Signal inputs is “ON” and the Reversing Valve
Enable Signal is “ON”. In this circumstance, the Reversing Valve Enable Relay
Output(s) will energize for indication purposes. In this mode, the Condenser
Output Signals will go to 100% and remain there until it leaves the Heating
Mode.
NOTE: The Reversing Valve Dipswitch 4 setting determines whether the
Reversing Valve Dipswitch 4 Relay is ON to Heat / OFF to Cool or ON to Cool /
OFF to Heat.
NOTE: The Reversing Valve Enable outputs are for indication only and are
not wired to anything.
SEQUENCE OF OPERATION
OPTIONS Dip Switch Settings
Table 2: OPTIONS Dip Switch/Head Pressure Setpoint Settings for Stand-Alone Operation
OPTIONS Dip
Switch Settings
| Head Pressure Setpoint
---|---
Air Cooled Condenser| Water Cooled Condenser
Binary Value| R410-A| R410-A
0| 340 (DEFAULT)| 235 (DEFAULT)
1| 260| 210
2| 270| 220
3| 280| 230
4| 290| 240
5| 300| 250
6| 310| 260
7| 320| 270
8| 330| 280
9| 340| 290
10| 350| 300
11| 360| 310
12| 370| 320
13| 380| 330
14| 390| 340
15| 400| 350
Table 3: ADDRESS Dip Switch 1 Condenser Type Settings
ADDRESS Dip Switch 1 Settings
Switch 1| Default SP| Description of Default Head Pressure
Setpoint
OFF| 340| Air Cooled Condenser using R410-A Refrigerant
ON| 235| Water Cooled Condenser using R410-A Refrigerant
Switch 1 determines Air or Water Cooled Condenser
NOTE: You must cycle power after setting Dip Switch values.
SEQUENCE OF OPERATION
OPTIONS Dip Switch Settings
Table 4: ADDRESS Dip Switch 2 Address Settings When in Communicating Mode
ADDRESS Dip Switch 2 Settings
Switch 2| Description
OFF| Set to OFF in a Stand Alone setup to use a 1 second condenser fan
enable delay. If connected to a VCMX/ SA Controller then set to OFF if this is
Module 1.
ON| Set to ON in a Stand Alone setup to use a 5 second condenser fan
enable delay. If connected to a VCMX/ SA Controller then set to ON if this is
Module 2.
Table 5: ADDRESS Dip Switch 3 Settings
ADDRESS Dip Switch 3 Settings
Switch 3| Description
OFF| Enable Circuit B Alarm
ON| Disable Circuit B Alarm when only one condenser is used.
Table 6: ADDRESS Dip Switch 4 Settings for Reversing Valve
ADDRESS Dip Switch 4 Settings
Switch 4| Description
OFF| Reversing Valve On to Heat/ Off to Cool
ON| Reversing Valve On to Cool/ Off to Heat
TROUBLESHOOTING
Head Pressure Module Valve / Fan Position Troubleshooting
Head Pressure Module Valve/Fan Position Troubleshooting
If configured for Water valve:
Aout Signal is 2 to 10 volts.
2 volts = 0% valve position or fully closed 10 volts = 100% valve position or
fully open PWM signal is not used for water valve but does modulate.
At Startup for cooling, valve will open to 75% or 8 volts for 3 minutes then
will modulate to try to maintain head pressure setpoint.
For heating, valve will open and stay at 100%.
If configured for Air Condenser Fan:
Aout Signal is 0 to 10 volts.
Minimum fan speed is 1 volt. (10%) Maximum fan speed is 10 volts. (100%)
Anything less than 1.5 volts the fan will be off.
PWM signal is 0 to 100% PWM+ (to ground) will always read 24 vdc.
PWM- (to ground) can be measured for volts dc and this formula will tell you
the percentage signal: (24 – measured value)/24 (measured value = PWM- to
ground)
PWM-
0 volts = 100% fan speed
6 volts = 75% fan speed
12 volts = 50% fan speed
18 volts = 25% fan speed 20.
4 volts = 15% fan speed Above 20.4 volts = 0% fan speed
At Startup for cooling, fan will start at 100% for 3 minutes and then will
modulate to try to maintain head pressure setpoint.
For heating, fan will run and stay at 100%.
Safeties :
If the head pressure signal is above 500 PSIG, fan will go to 100% (high
pressure safety).
If the head pressure signal is below 1 PSIG, fan will go to 100% (assuming bad
sensor).
If the head pressure rises 50 PSI above setpoint, the condenser signal will go
to 100%.
TROUBLESHOOTING
Troubleshooting for Stand-Alone Mode
If you suspect or encounter general problems during operation of the Two Condenser Head Pressure II Module while in Stand Alone Mode, follow the Troubleshooting Flowchart in Figure 5, below.
Head Pressure Control Troubleshooting Flowchart (Stand-Alone Mode)
Figure 5: Two Condenser Head Pressure II Module Troubleshooting Diagram
Pressure Transducer Troubleshooting and LEDs
Pressure Transducer Troubleshooting
If you suspect there is a problem with the Module related to pressure transducer measurements, reference Table 7 below.
Table 7: Two Condenser Head Pressure II Module Transducer Chart
Pressure Sensor Chart
Voltage| Pressure| Voltage| Pressure
0.5| 0| 2.6| 350
0.6| 17| 2.7| 367
0.7| 33| 2.8| 384
0.8| 50| 2.9| 400
0.9| 67| 3.0| 417
1.0| 83| 3.1| 434
1.1| 100| 3.2| 450
1.2| 117| 3.3| 467
1.3| 133| 3.4| 484
1.4| 150| 3.5| 500
1.5| 167| 3.6| 517
1.6| 183| 3.7| 534
1.7| 200| 3.8| 550
1.8| 217| 3.9| 567
1.9| 233| 4.0| 584
2.0| 250| 4.1| 600
2.1| 267| 4.2| 617
2.2| 283| 4.3| 634
2.3| 300| 4.4| 650
2.4| 317| 4.5| 667
2.5| 334|
Using LEDs to Verify Operation
The Two Condenser Head Pressure II Module is equipped with LEDs that can be used to verify operation and perform troubleshooting. There are LEDs for communication, operation modes, diagnostic codes, and relays. The Two Condenser Head Pressure Module has eight LEDs—one for power, one for operation status, one for communication, one for alarms, and four for compressor relays. See Figure 6, page 16, for the LED locations. The LEDs associated with these inputs and outputs allow you to see what is active without using a voltmeter.
1Status LEDs
“COMM” – This LED will light up to indicate Communications with the VCM-X
series or SA series controller. If Communications are established, the COMM
LED will blink. You should not see this LED light up in stand-alone mode,
because there would be no communications with the VCM-X series or SA series
controller.
“ALARM” – This is the diagnostic blink code LED. It will light up and blink
out diagnostic codes. See Table 8 below for Diagnostic Blink Code
descriptions. The blink code descriptions are also located on the Module’s
front cover.
Table 8: ALARM LED Blink Codes
| No. of Blinks | Alarm |
|---|---|
| 0 | No Problems |
| 1 | No Sensors Detected |
| 2 | High Head Pressure Detected |
| 3 | Low Head Pressure Detected |
“STAT” – This is the status blink code LED. It will light up and first blink the address of the Module. It will then blink out the quantity of sensors installed. See Table 9 below for Status Blink Code descriptions. The blink code descriptions are also located on the Module’s front cover.
Table 9: STAT LED Blink Codes
| No. of Blinks | Status |
|---|---|
| Random | Blinks Quantity of Sensors Installed |
TROUBLESHOOTING
LED Diagnostics
2 Module LEDs
“R1” – This LED will light up whenever Condenser A Enable Relay is enabled and
will stay lit as long as the relay is active.
“R2” – This LED will light up when the Reversing Valve A Enable Relay is
enabled and will stay lit as long as the Reversing Valve A is active.
“R3” – This LED will light up whenever Condenser B Enable Relay is enabled and
will stay lit as long as the relay is active.
“R4” – This LED will light up when the Reversing Valve B Enable Relay is
enabled and will stay lit as long as the Reversing Valve B is active.
Figure 6: LED Locations
LED Diagnostics
“PWR” LED: When the Two Condenser Head Pressure II Module is powered up, the
PWR LED (located below the address switches) should light up and stay on
continuously. If it does not light up, check to be sure that the power wiring
is connected to the board, the connections are tight, and the VCM-X series or
SA series controller is powered. If after making all these checks, the PWR LED
does not light up, the module is probably defective.
“ COMM” LED: When the Two Condenser Head Pressure II Module is powered up
while in Stand Alone Mode, the COMM LED does not light up. When the module is
connected to a VCM-X series or SA series controller, the COMM LED should light
up, indicating Communications. Each time Communications are detected, this LED
should continuously blink on and off, for a half second. This LED should never
stop checking for a Communications signal. If it does not light up, check to
be sure that the power wiring is connected to the board, the connections are
tight, and the VCM-X series or SA series controller is configured for Head
Pressure Control and is powered up. If after making all these checks, the COMM
LED does not light up, the board is probably defective.
“STAT” LED: As previously described, when the module is first powered up,
the STAT LED will blink out the number of installed sensors.
“ALARM” LED: As previously described, this LED will blink on and off to
indicate alarms and diagnostics.
Other Checks
NOTE: The Two Condenser Head Pressure II Module contains no user-
serviceable parts. Contact qualified technical personnel if your module is not
operating correctly
HP2C2 Technical Guide Rev. H · 230707
AAON Controls Tech Support:
866-918-1100 |
918-382-6450 |
[email protected] Monday through
Friday, 7:00 AM to 5:00 PM Central Time Controls Tech Support website:
www.aaon.com/aaon-controls-technical-support
AAON Factory Technical Support:
918-382-6450 |
[email protected]
NOTE: Before calling Technical Support, please have the model and serial
number of the unit available.
PARTS: For replacement parts, please contact your local AAON
Representative.
HP2C2 REVISION LOG
REVISION AND DATE| CHANGE
Rev. E, April 1, 2015| Previous version
Rev. F, September 1, 2022| Added note the HSSC cable is no longer supplied
with this module, updated HP2C2 labels
Rev G, June 1, 2023| Added function to address DIP switch 2
Rev H, July 7, 2023| Corrected wiring diagrams
HP2C2 PARTS REFERENCE
PART DESCRIPTION| PART NUMBER
Two Condenser Head Pressure II Module| ASM01891
All manuals are also available for download from www.aaon.com
AAON 2425 South Yukon Ave.
Tulsa, OK 74107-2728
www.aaon.com
Factory Technical Support Phone:
918-382-6450 AAON® Controls Support:
866-918-1100 It is the intent of AAON®
to provide accurate and current product information. However, in the interest
of product improvement, AAON® reserves the right to change pricing,
specifications, and/or design of its product without notice, obligation, or
liability.
AAON® P/N: V22100, Rev H Copyright July 7, 2023 AAON, Inc.
AAON® is a registered trademark of AAON, Inc., Tulsa, OK.
AAON® assumes no responsibility for errors or omissions in this document.
This document is subject to change without notice.