Bosch FHP EC120 User Manual

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Installation, operation and Maintenance Manual

EC Large Series

T111970289 (01/15)

072, 096, 120, 150, 151, 180, 181, 210, 240, 242, 300, 360.

Table of Contents

Questions and Answers:

S
Sheila MillerAug 14, 2025
Why is my Bosch FHP EC120 not cooling or heating enough?
- J
  Jeffrey GomezAug 14, 2025
  Several factors can cause insufficient cooling or heating in your Bosch Heat Pump. It could be due to an undersized unit (recalculate heating/cooling loads, adding insulation/shading), loss of conditioned air (check for leaks in ductwork, doors, or windows), airflow issues (replace dirty filter), low refrigerant charge, a defective compressor (check discharge and suction pressures), a defective reversing valve, incorrect operating pressures (compare to pressure/temperature chart), a restricted or defective TXV (replace if needed), or contamination in the refrigerant system (reclaim refrigerant, replace filter dryer, evacuate, and recharge).
M
Monique FosterAug 17, 2025
Why is my Bosch FHP EC120 off on high pressure control?
- J
  Jasmin McphersonAug 17, 2025
  Your Bosch Heat Pump might be off due to the high-pressure control being triggered. This can happen because the discharge pressure is too high. In cooling mode, this could be due to a lack of water flow, entering water that is too warm, or a scaled/plugged condenser. In heating mode, it could be due to a lack of airflow, an inoperative blower, a clogged filter, or ductwork restrictions. Another cause could be that the unit is overcharged with refrigerant, needing to be reclaimed, evacuated, and recharged with the factory-recommended amount. Lastly, there might be a defective or improperly calibrated high-pressure switch.
J
Janet BrockAug 21, 2025
Why is my Bosch Heat Pump unit off on low pressure control?
- G
  Gregory SmithAug 21, 2025
  Your Bosch Heat Pump may be shutting off due to the low-pressure control. This can be caused by low suction pressure. In cooling mode, this could be due to inadequate airflow, entering air that is too cold, an inoperative blower, a clogged filter, or restrictions in the ductwork. In heating mode, this could be due to a lack of water flow, entering water that is too cold, or a scaled or plugged condenser. Another possible cause is a low refrigerant charge; check for leaks, repair them, evacuate the system, and recharge it with the factory-recommended amount. Finally, the low-pressure switch itself might be defective or improperly calibrated.
Z
Zachary MckinneyAug 27, 2025
What to do if my Bosch FHP EC120 unit short cycles?
- K
  Karen WilliamsAug 27, 2025
  If your Bosch Heat Pump is short cycling, it could be due to several reasons. First, the unit might be oversized, requiring a recalculation of heating and cooling loads. Second, the thermostat could be installed near a supply air grill; if so, relocate it and readjust the heat anticipator. Finally, there may be issues with the wiring and controls, such as a defective or improperly calibrated low-pressure switch.
B
Benjamin SpencerAug 30, 2025
Why is my Bosch FHP EC120 blower operating but the compressor does not?
- T
  Tyler GillAug 31, 2025
  If the blower in your Bosch Heat Pump is working but the compressor isn't, check the thermostat setting, calibration, and wiring. Inspect the wiring at the compressor, capacitor, or contactor for any loose or broken wires. Also, check the UPM board red default L.E.D. for a Blink Code. If the compressor overload is open, and the compressor is cool and won't reset, replace the compressor. If the compressor motor is grounded (internal winding grounded to the compressor shell), replace the compressor and install a suction filter dryer if there was a compressor burnout. Lastly, after the compressor has cooled, check the continuity of the compressor windings; if they're open, replace the compressor.
S
Scott RasmussenSep 3, 2025
What causes no or low flow in my Bosch FHP EC120 Heat Pump?
- S
  Stephanie ReynoldsSep 3, 2025
  No or low flow in your Bosch Heat Pump can stem from several issues. Begin by checking the power supply and ensuring the on/off switch is in the “ON” position. Verify the compressor contactor is engaged. Inspect for broken or loose wires and repair or tighten them as needed. Purge any air from the piping system. If the pump shaft/impeller is stuck, remove the pump cartridge and clean it. If the pump is defective, replace it. Lastly, check for kinked or undersized water piping and repair any kinks, ensuring the line size is correct.
D
davisderekSep 6, 2025
What causes high water temperature in Bosch FHP EC120?
- D
  David WilliamsSep 6, 2025
  High water temperature in your Bosch Heat Pump may be due to a water temperature limit being closed, a stuck limit switch, or a sensor not securely attached to the line.
M
Michelle WuSep 9, 2025
What causes low heat output in Bosch FHP EC120 Heat Pump?
- K
  Keith HayesSep 10, 2025
  Low heat output in your Bosch Heat Pump can be caused by a scaled or fouled heat exchanger. Cleaning the heat exchanger might resolve the issue.

Bosch FHP EC120 Specifications

General

Brand	Bosch
Model	FHP EC120
Category	Heat Pump
Language	English

Summary

Safety and System Information

Understanding Safety Warnings

Explains warning symbols and keywords used in the manual.

Unit Initial Setup

Initial Unit Inspection Procedures

Steps for inspecting the unit upon arrival and before installation.

Thermostat and Unit Controls

Thermostat Wiring and Connections

Instructions for connecting thermostats to the ECM interface board.

UPM Controller and Safety

UPM Controller and Safety Devices

Overview of safety devices and the Unit Protection Module (UPM).

UPM Board Features and Settings

UPM Board Default Configuration

UPM Board Operational Features

Explanation of UPM board features like anti-short cycle and random start.

UPM Fault Management

UPM Board LED Fault Indicators

Explanation of UPM board LED indicators and fault blink codes.

Intelligent Reset and Lockout Procedures

Details on intelligent reset and hard lockout conditions.

Thermostat and Water Quality

Electronic Thermostat Installation Guide

Water Quality Importance and Maintenance

Importance of water quality for heat pump performance and longevity.

UPM Operational Sequence

UPM Control Sequence of Operation

Flowchart detailing the UPM control sequence for unit operation.

Water Quality Standards

Water Quality Parameters and Acceptable Values

Start-Up and Heat Recovery Features

Heat Pump Initial Start-Up Process

Step-by-step guide for starting up the heat pump unit.

Operation Modes and Application Considerations

Cooling Mode Sequence of Operation

Describes the sequence of operations during cooling mode.

Heating Mode Sequence of Operation

Describes the sequence of operations during heating mode.

Installation Checks and Start-Up

Pre-Energization System Checkout

Checks to perform before energizing the unit after installation.

Heat Pump Unit Start-Up Procedure

Step-by-step guide for starting up the heat pump unit.

Maintenance

Routine Maintenance Procedures

Guidelines for regular maintenance tasks like filter changes and annual checkups.

Troubleshooting Guide

Troubleshooting Overview and UPM Board LEDs

Guide to troubleshooting common issues and interpreting UPM board LEDs.

Unit Troubleshooting Common Problems

Diagnosing and correcting common unit operational problems.

Advanced Unit Troubleshooting

Advanced Unit Troubleshooting

Further troubleshooting for pressure controls and unit performance.

HRP Troubleshooting

Heat Recovery Package Troubleshooting

Troubleshooting specific issues related to the Heat Recovery Package.

Operating Temperatures and Pressures

Operating Temperatures and Pressures (EC072, EC096)

Operating Temperatures and Pressures (EC150, EC151, EC120)

Operating Temperatures and Pressures (EC240, EC242, EC300, EC360)

Wiring Diagrams

Wiring Diagram for Belt Drive Motor (3-25 Ton)

Wiring Diagram with Economizer & Hot Gas Reheat

Wiring Diagram for Boilerless Control Systems

Wiring Diagram for Belt Drive Motor (30 Ton)

Wiring Diagram with UPM II Economizer & Hot Gas Reheat

Wiring Diagram with Dual Power Supply and FAR

Wiring Diagram for Modulating Re-Heat

Wiring Diagram for ABB Drive and HGRH

Wiring Diagram for Boilerless Control System

Wiring Diagram with UPM II and FAR

Wiring Diagram for UPM II 2 Stage Economizer

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