Kaisai MONO KHC-22RX3

Questions and Answers

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Thomas HarrisAug 12, 2025
How to troubleshoot a Kaisai MONO KHC-22RX3 Heat Pump not heating or cooling properly?
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  jonesannAug 13, 2025
  If your Kaisai Heat Pump is on but not heating or cooling as expected, several factors could be at play. First, verify that the temperature settings on your controller are correct, paying attention to T4HMAX and T4HMIN in heat mode, T4CMAX and T4CMIN in cool mode, and T4DHWMAX and T4DHWMIN in DHW mode. Also, ensure adequate water flow by checking that all shut-off valves are fully open, cleaning the water filter if necessary, purging any air from the system, and confirming sufficient water pressure (above 1 bar when the water is cold). Finally, check the expansion vessel and make sure that the water volume in the installation is above the minimum required value.
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Willie TuckerAug 16, 2025
What to do if the Kaisai MONO KHC-22RX3 compressor is not starting?
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  lunalisaAug 17, 2025
  If your Kaisai Heat Pump's compressor isn't starting for space or domestic water heating, it might be due to a low water temperature. In this case, the system should use a backup heater to reach a minimum water temperature of 12°C. Check that the backup heater power supply is correct, the thermal fuse is closed, the thermal protector is not activated, and the backup heater contactors are not broken.
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jeffreywadeAug 20, 2025
Why does the water pressure relief valve open on my Kaisai MONO KHC-22RX3?
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  boylejillAug 20, 2025
  If the water pressure relief valve on your Kaisai Heat Pump opens, it could be due to a broken expansion vessel. In this case, the expansion vessel should be replaced. Alternatively, the filling water pressure in the installation might be too high. Ensure that the filling water pressure is about 0.15~0.20MPa.
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Roberto BurtonAug 25, 2025
Why is there a space heating capacity shortage at low outdoor temperatures with my Kaisai MONO KHC-22RX3 Heat Pump?
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  David McdanielAug 25, 2025
  If you're experiencing a space heating capacity shortage with your Kaisai Heat Pump at low outdoor temperatures, ensure that the "OTHER HEATING SOURCE/ BACKUP HEATER" is enabled. Also, check whether the thermal protector of the backup heater has been activated. It's also important to verify if the booster heater is running, as the backup heater and booster heater can’t operate simultaneously. Also, check that the “t_DHWHP_MAX” and “t_DHWHP_RESTRICT” are configured appropriately, ensure that the “DHW PRIORITY” in the user interface is disabled and enable the “T4_TBH_ON” in the user interface/FOR SERVICEMAN to activate the booster heater for domestic water heating.
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aadamsAug 27, 2025
Why is my Kaisai MONO KHC-22RX3 pump making noise (cavitation)?
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  Brian HarrisAug 27, 2025
  If your Kaisai Heat Pump pump is making noise (cavitation), it could be due to air in the system. If so, purge the air. Another possible cause is that the water pressure at the pump inlet is too low. Check on the manometer that there is sufficient water pressure (must be > 1 bar when the water is cold). Also, check that the manometer and the expansion vessel are not broken and that the setting of the pre-pressure of the expansion vessel is correct.
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Tyler HansenAug 31, 2025
What to do if the water pressure relief valve leaks in my Kaisai Heat Pump?
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  Evan Cox MDAug 31, 2025
  If the water pressure relief valve on your Kaisai Heat Pump leaks, it could be that dirt is blocking the water pressure relief valve outlet. Check the valve by turning the red knob counter-clockwise. If you don't hear a clacking sound, contact your local dealer. If water continues to run out, close both the water inlet and outlet shut-off valves and then contact your local dealer.
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kevinharrisonSep 4, 2025
What to do if DHW mode can’t change to Heat mode immediately in Kaisai MONO KHC-22RX3 Heat Pump?
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  Tammie GrahamSep 4, 2025
  If your Kaisai Heat Pump in DHW mode can’t switch to heat mode immediately, it could be due to several reasons. First, set "t_DHWHP_MAX" to the minimum value, suggested as 60min. If the circulating pump out of the unit is not controlled by the unit, try connecting it to the unit. Also, add a 3-way valve at the inlet of the fan coil to ensure enough water flow. If you have manually turned on the FAST WATER function, manually turn it off. Finally, set "T4DHWMIN", the suggested value is ? -5? and set "T4_TBH_ON", the suggested value is ? 5?.
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isaiah12Sep 8, 2025
Why does DHW mode stop before setpoint, and heat mode won't start on my Kaisai MONO KHC-22RX3 Heat Pump?
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  Elizabeth McdonaldSep 8, 2025
  If your Kaisai Heat Pump stops working in DHW mode before reaching the setpoint, and space heating is required but the unit remains in DHW mode, this may be because the surface of the coil in the tank is not large enough. The solution is the same as for Symptom 7. Also, if TBH or AHS is not available, the heat pump will stay in DHW mode until "t_DHWHP_MAX" is reached or the setpoint is reached. Consider adding TBH or AHS for DHW mode, ensuring they are controlled by the unit.

Summary

Safety Precautions

Meaning of Safety Symbols

Explains the meaning of DANGER, WARNING, CAUTION, and NOTE symbols used in the manual.

Unit Symbols Explanation

Illustrates and describes symbols displayed on the indoor and outdoor units.

Safety Precautions Details

DANGER Hazards

Highlights critical hazards that can cause death or serious injury if not avoided.

WARNING Hazards

Alerts to potential hazards that could result in death or serious injury if not avoided.

CAUTION Hazards

Warns of potential hazards leading to minor injury or unsafe practices.

General Information and Installation

Unsuitable Installation Locations

Lists unsuitable installation locations to prevent damage or hazards.

Product Disposal

Provides instructions for proper product disposal and environmental impact.

Unit Capabilities and Compatibility

Overview of the unit's capabilities and compatible systems.

General Information Details

Operation Range

Details operational temperature and flow ranges for cooling, heating, and DHW modes.

Accessories

Supplied Accessories

Lists components provided with the unit.

Available Accessories

Lists optional accessories that can be purchased separately.

Before Installation

Unit Handling

Provides guidance on safe handling procedures for the unit due to its size and weight.

Installation Site

Selecting a Location in Cold Climates

Guidelines for choosing an installation site in cold weather conditions.

Selecting a Location in Hot Climates

Guidelines for choosing an installation site in hot weather conditions.

Installation Precautions

Unit Dimensions

Provides the physical dimensions of the unit for installation planning.

Installation Requirements

Outlines the necessary requirements for securely installing the unit.

Installation Precautions Details

Drain Hole Position

Specifies the correct placement for the drain hole to ensure proper water drainage.

Servicing Space Requirements

Defines the necessary clearances around the unit for maintenance and servicing.

Typical Applications

Application 1: Space Heating with Room Thermostat

Illustrates space heating with a room thermostat connected to the unit.

Typical Applications Overview

Application 2: Heating with DHW and Solar System

Illustrates space heating with domestic hot water and solar heating system.

Typical Applications Overview 2

Application 3: Cooling, Heating, DHW with Thermostat & FCU

Shows cooling, heating, and DHW with room thermostat and fan coil units.

Typical Applications Overview 3

Application 4: Space Heating with Auxiliary Boiler

Illustrates space heating with an auxiliary boiler (alternating operation).

Typical Applications Overview 4

Application 5: Dual Setpoint Function with Two Room Thermostats

Shows dual setpoint function with two room thermostats for heating/cooling.

Typical Applications Overview 5

Application 6: Dual Setpoint Function without Room Thermostat

Dual setpoint function without room thermostat for floor heating and fan coil units.

Typical Applications Overview 6

Application 7: Parallel Units for Cooling, Heating, and DHW

Illustrates parallel units for cooling, heating, and hot water.

Overview of the Unit

Disassembling the Unit

Provides instructions on how to disassemble the unit to access internal components.

Hydraulic Module

Details the components within the hydraulic module, part of main components.

Overview of the Unit Details

Hydraulic System Diagram

Presents a diagram illustrating the hydraulic system of the unit.

Electronic Control Box

Shows the layout of the electronic control box, front and back views.

Overview of the Unit Details 2

Main Control Board of Indoor Unit

Details the main control board of the indoor unit, including connector layout.

Overview of the Unit Details 3

Inverter Module

Shows the layout and connections of the inverter module.

Overview of the Unit Details 4

Main Control Board of Unit

Details the main control board of the unit, including connector layout.

Overview of the Unit Details 5

Filter Board

Illustrates the filter board and its connections.

Water Piping

Check the Water Circuit

Provides instructions for checking the water circuit before operation.

Water Piping Details

Water Volume and Expansion Vessel Pre-Pressure Checks

Explains how to check water volume and adjust expansion vessel pre-pressure.

Water Piping Details 2

Calculating Expansion Vessel Pre-pressure

Details calculation method for expansion vessel pre-pressure based on height difference.

Checking Maximum Allowed Water Volume

Describes how to check the maximum allowed water volume in the system.

Water Circuit Connection

Guides on correctly connecting the water circuit piping.

Water Piping Details 3

Water Circuit Anti-Freeze Protection

Explains methods to protect the water circuit from freezing.

Freeze Protection by Glycol

Details using glycol for freeze protection and required concentrations.

Water Piping Details 4

Freeze Protection by Freeze Protection Valves

Describes the use of freeze protection valves to drain the system.

Adding Water

Provides instructions on how to add water to the system and purge air.

Water Piping Insulation

Field Wiring Precautions

Outlines essential precautions for safe and correct electrical wiring.

Field Wiring Overview

Provides a general overview of the field wiring connections.

Water Piping Insulation Details

Standard Wiring Components Specifications

Lists specifications for standard wiring components used in the system.

System Parallel Connection

Details how to connect multiple units in a parallel system for control.

Water Piping Insulation Details 2

Power Supply Wiring Precautions

Specific precautions for wiring the power supply to the unit.

Water Piping Insulation Details 3

Other Component Connections

Explains how to connect various external components like thermostats and pumps.

Water Piping Insulation Details 4

Room Thermostat Wiring Methods

Describes wiring methods for different types of room thermostats.

Water Piping Insulation Details 5

3-Way Valve SV3 Wiring

Details the wiring for the 3-way valve (SV3).

Pump Control Signal Wiring

Shows wiring for various pump control signals.

Water Piping Insulation Details 6

Tank Booster Heater Wiring

Explains wiring for the tank booster heater.

External Backup Heater Kit Wiring

Details wiring for an optional external backup heater.

Antifreeze E-heating Tape Wiring

Describes wiring for external antifreeze heating tape.

Unit Running State Output Wiring

Shows wiring for unit running state output signals.

Additional Heat Source Control Wiring

Explains wiring for additional heat source control signals.

Water Piping Insulation Details 7

Defrosting Signal Output Wiring

Wiring for defrosting signal output.

Wired Controller Wiring

Details wiring for the wired controller.

Other Functional Ports Wiring

Lists connections for other functional ports like room thermostat and smart grid.

Start-Up and Configuration

Climate Related Curves

Explains how climate-related curves affect water temperature settings.

Start-Up and Configuration Details

DIP Switch Settings Overview

Describes the function and overview of DIP switch settings.

Function Setting

Details specific function settings configurable via DIP switches.

Start-Up and Configuration Details 2

Initial Start-up in Low Outdoor Ambient Temperature

Provides guidance for initial start-up in cold ambient conditions.

Pre-Operation Checks

Lists essential checks to perform before initial unit start-up.

Start-Up and Configuration Details 3

Powering Up the Unit

Describes the process of powering up the unit for the first time.

Setting the Pump Speed

Explains how to adjust the pump speed for optimal system performance.

Start-Up and Configuration Details 4

Field Settings

Introduces the section for configuring unit parameters via the "FOR SERVICEMAN" menu.

Field Settings

DHW Mode Setting

Settings related to Domestic Hot Water (DHW) mode operation.

Cool Mode Setting

Settings for the cooling mode operation.

Heat Mode Setting

Settings for the heating mode operation.

Auto Mode Setting

Configuration settings for the automatic operating mode.

Temp. Type Setting

Selects temperature source (water flow or room) for unit control.

Field Settings Details

Room Thermostat Configuration

Configuration for room thermostat usage and settings.

Field Settings Details 2

Other Heating Source Settings

Settings for backup heaters, additional heat sources, and solar kits.

Holiday Away Setting

Configures settings for holiday or away mode to prevent freezing.

Service Call Setting

Allows setting the local dealer's phone number for service calls.

Restore Factory Settings

Restores all user-configured parameters to factory defaults.

Field Settings Details 3

Test Run

Guides on performing manual test runs for various unit functions.

Field Settings Details 4

Special Function

Accesses special functions like floor heating preheating and drying.

Field Settings Details 5

Auto Restart Function

Configures the unit's automatic restart behavior after a power failure.

Field Settings Details 6

Power Input Limitation

Sets limits for the unit's power input.

Input Define

Defines the function of various input terminals and switches.

Cascade Set

Configures settings for cascade operation of multiple units.

HMI Address Set

Sets the HMI address for communication, especially in master/slave configurations.

Test Run and Final Checks

Final Checks

Lists final checks to be performed after unit installation and before operation.

Test Run Operation (Manually)

Describes how to perform manual test runs to verify unit functions.

Maintenance and Service

Annual Maintenance Checks

Lists essential checks and inspections to be performed annually by a qualified technician.

Trouble Shooting

General Guidelines

Provides general guidelines for troubleshooting unit issues.

General Symptoms

Lists common symptoms and their potential causes and corrective actions.

Operation Parameter Review

Displays current operational parameters for installer review.

Trouble Shooting Details

Error Codes

Lists error codes, their causes, and corrective actions for troubleshooting.

Technical Specifications

Information Servicing

Area Safety Checks

Safety checks required for the work area before servicing.

Work Procedure and Area Safety

Describes procedures for personnel and work area safety during maintenance.

Refrigerant Handling and Fire Prevention

Procedures for detecting refrigerant, fire prevention, and ventilation.

Refrigeration Equipment Checks

Checks on components and markings of refrigeration equipment.

Electrical Device Safety Checks

Safety checks and procedures for electrical components during repair.

Repairs to Sealed Components

Procedures for safely performing repairs on sealed components.

Information Servicing Details

Intrinsically Safe Components and Cabling Checks

Guidelines for intrinsically safe components and cabling integrity.

Flammable Refrigerant Detection and Leak Detection

Methods for detecting flammable refrigerants and leaks.

Refrigerant Removal and Evacuation

Procedures for refrigerant removal and evacuation.

Annex A: Refrigerant Cycle

Refrigerant Cycle Diagram

Diagram illustrating the refrigerant cycle of the unit.