Why is there low heat output from my Bosch SM070 Heat Pump?
- TTeresa CampbellSep 14, 2025
Low heat output from your Bosch Heat Pump could be due to a scaled or fouled heat exchanger. Clean the heat exchanger to resolve this issue.

Why is there low heat output from my Bosch SM070 Heat Pump?
Low heat output from your Bosch Heat Pump could be due to a scaled or fouled heat exchanger. Clean the heat exchanger to resolve this issue.
Why is the water temperature high in my Bosch SM070 Heat Pump?
High water temperature in your Bosch Heat Pump may be due to a stuck water temperature limit switch or a sensor that is not securely attached to the line.
What to do if my Bosch SM070 has no flow or low flow?
If your Bosch Heat Pump experiences no flow or low flow, here's what you can check: * Verify the power supply. * Ensure the on/off switch is in the 'ON' position. * Engage the heat pump contactor. * Repair or tighten any broken or loose wires. * Purge air from the piping system. * Remove the pump cartridge and clean it if the pump shaft/impeller is stuck. * Replace the pump if it is defective. * Repair any kinks in the water piping and check for proper line size.
What to do if my Bosch SM070 Heat Pump is short cycling?
If your Bosch Heat Pump is short cycling, several factors could be responsible. The unit might be oversized, requiring a recalculation of heating and cooling loads. The thermostat could be installed near a supply air grill, necessitating relocation, or the heat anticipator may need readjustment. Additionally, check for a defective or improperly calibrated low-pressure switch.
What to do if my Bosch SM070 Heat Pump unit shuts off due to high pressure?
If your Bosch Heat Pump shuts off on high pressure control, it could be due to several reasons. In cooling mode, it could be due to a lack of or inadequate water flow, entering water temperature being too warm, or a scaled or plugged condenser. In heating mode, it may be caused by a lack of or inadequate air flow, an inoperative blower, a clogged filter, or restrictions in the duct work. The unit might also be overcharged with refrigerant, requiring you to reclaim refrigerant, evacuate, and recharge with the factory-recommended charge. Finally, check for a defective or improperly calibrated high-pressure switch.
How to reduce noise levels from my Bosch SM070?
If you're experiencing objectionable noise levels from your Bosch Heat Pump, it could be due to several reasons. Air noise might be the issue; ensure the ductwork and grilles are properly sized for the unit's airflow. The fan speed setting could be too high; consult the blower performance table and reduce fan speed if possible. Structure-borne noise can also be a factor; try mounting the unit on a vibration pad. Also, make sure the unit cabinet isn't touching a wall or other building component; adjust the unit's location to prevent contact.
How to stop water hammer in my Bosch Heat Pump system?
If you're experiencing water hammer with your Bosch Heat Pump, it's likely due to fast-closing valves being installed. Change the valves to a slow-close type to resolve this issue.
Why does Bosch Heat Pump UPM board show fault in test mode?
If your Bosch Heat Pump operates in test mode but the UPM board shows a fault, it's likely because the UPM board is in test mode. Change the dip switch setting to Normal. This is part of the test mode to ensure that freeze 1 and freeze 2 sensors are correctly located.
Why does my Bosch SM070 have no delay on startup?
If your Bosch Heat Pump operates but has no or short delays on start or restart, the UPM board might be in test mode. To resolve this, change the dip switch setting to Normal.
Why isn't my Bosch SM070 Heat Pump switching between heating and cooling?
If your Bosch Heat Pump isn't shifting between cooling and heating modes, a faulty solenoid could be the cause. Check that the reversing valve solenoid is receiving 24 VAC; if it is, check the resistance of the solenoid, as an open circuit may indicate a burned-out solenoid. A miswired or faulty thermostat could also be the problem; ensure that the reversing valve thermostat wire is connected to the "O" terminal of the thermostat. Finally, check for a loose wire on the "O" terminal, ensuring that the wires from the thermostat to the unit are securely connected, as well as the wires from the electrical box to the reversing valve.
Identifies symbols used for warnings and their severity levels.
Indicates important information where there is no risk to property or people.
Warns about hazards from system pressure and electrical components.
Emphasizes turning off main power before service to prevent electrical shock.
Advises observing precautions, following codes, wearing safety gear, and having fire extinguisher.
Specifies that refrigerant circuit must be serviced by qualified technicians.
Warns against using units for heating/cooling during construction to avoid damage.
Highlights performance, efficiency, AHRI ISO, UL1995, and CAN/CSA C22.2 standards.
Specifies entering fluid temperature ranges for heating and cooling modes.
Notes limitations on air/fluid flow rates and temperatures under extreme conditions.
Recommends 50°F EWT for well water; antifreeze required for closed loops below 45°F.
Lists Vertical, Horizontal, Counter-Flow configs and factory-installed options.
Mentions an externally mounted LCD for unit diagnosis without opening the cabinet.
Specifies indoor installation, easy access for service, and sufficient room for connections.
Ensures return air path and avoids locating units in areas subject to freezing.
Describes field configurable blower orientation: end blow or straight through.
Provides instructions for reconfiguring the blower on left-hand horizontal units.
Notes that discharge air configuration changes are not possible with electric heat.
Describes the dedicated downflow configuration for Counter-Flow units.
Details field configuration for Vertical units by relocating E-box and reorienting blower.
States discharge air configuration changes are not possible with electric heat.
Instructions for removing the panel belt to access internal components.
Recommends two persons for safety precautions when performing panel removal.
Provides instructions for identifying and installing corner caps on the unit.
Details mounting vertical units level on vibration absorbing pads.
Describes suspending horizontal units above ceilings using threaded rods.
Instructions for installing the hanging bracket kit for suspended unit mounting.
Details relocating the condensate drain connection for left-hand to right-hand return.
Explains connecting the drain line, pitching it away from the unit, and including a trap.
Specifies supply and return air outlet collars and flanges for duct connections.
Recommends flexible connectors, insulation, and proper duct sizing for performance.
Ensures no direct air path to heat pump and requires a 90-degree turn in return air.
Recommends piping size, copper or cupro-nickel condenser based on water quality.
Advises insulating lines, using ball valves, and checking for leaks.
Warns against exceeding recommended water flow rates to prevent heat exchanger damage.
Details attaching conduit and connecting ground lead and power leads.
Specifies two separate power supplies for units with internal electric heat.
Describes UPM controller functions, safety devices, and board indicators.
Explains connections for thermostat malfunction lights.
Details UPM controller functions and safety controls like high/low pressure switches.
Describes water and evaporator side freeze protection sensor functions and settings.
Explains the condensate overflow protection sensor location and connection.
Lists default settings for UPM board parameters like TEMP, LOCKOUT, RESET, ALARM, TEST.
Shows default positions for UPM DIP switches for lockout, reset, alarm, and test.
Details Anti-Short Cycle Timer and Random Start features of the UPM board.
Explains brownout/surge protection and how the unit behaves during power interruptions.
Describes malfunction output (dry contact) and display output (pulse) functions.
Explains freeze sensor settings, soft/hard lockout conditions, and recommended flow switch.
Details intelligent reset procedures and manual lockout reset methods.
Describes the ECM interface board's role in translating thermostat inputs to ECM motor commands.
Lists thermostat connections and their functions for compressor, fan, and auxiliary heat.
Explains how to adjust airflow using the selector for application requirements.
Details selecting between Hot Gas Reheat and fan-only dehumidification modes.
Describes ECM motor efficiency, flatter fan curve, and simple operation.
Provides instructions for changing speed taps to adjust airflow and static options.
Explains HGRH for cooling and dehumidifying return air without altering sensible temperature.
Details supplemental electric heat for auxiliary or emergency backup heat.
Describes HRP for heating potable water using waste heat from compressor discharge.
Explains HRP operation, temperature monitoring, and draining to prevent freezing.
Details ECM motor for constant airflow and optimized power consumption.
Explains DPS switch function to prevent compressor operation without adequate water flow.
Describes pump relay for energizing supply pumps and Comfort Alert for troubleshooting.
Explains SSA reducing starting current, extending compressor life, and optimizing starts.
Lists operational voltage, environmental range, IP rating, and current ratings for SSA.
Describes LED status and controller behavior under normal and undervoltage conditions.
Details LED indications and controller actions for overcurrent and incomplete ramp alarms.
Explains green and red LED indications for power supply and alarm conditions.
Details SSA recovery behavior after undervoltage, overcurrent, and incomplete ramp alarms.
Provides steps for preparing the water tank for HRP installation.
Details piping requirements, insulation, and isolation valves for the HRP system.
Ensures valves are open, never operate HR pump dry, and checks HR pump operation.
Checks for expected water temperature difference across the heat recovery system.
Describes unit operation in cooling mode, including fan and compressor staging.
Details unit operation in heating mode, including auxiliary and emergency heat.
Discusses copper suitability, water quality testing, and solenoid valve use for well water.
Details loop temperature maintenance, heat rejection, and chemical treatment for cooling towers.
Covers air elimination in closed loops, boiler use for heating, and temperature exposure risks.
Emphasizes cleaning and flushing the water system before connecting the unit.
Highlights need for specialized knowledge, training, and GLP for geothermal installations.
Mentions use of anti-freeze solutions for low evaporating conditions in geothermal systems.
Lists checks for supply voltage, electrical connections, fusing, wiring, and piping.
Ensures proper grounding and free rotation of the blower assembly.
Confirms unit serviceability and that all access panels are secured.
Guides setting thermostat for cooling mode, checking operation, and system equalization.
Guides setting thermostat for heating mode and checking operation.
Recommends filter maintenance intervals based on environment type.
Suggests annual performance checks by a licensed refrigeration mechanic.
Advises on blower motor lubrication, recommending SAE-20 non-detergent oil.
Recommends annual cleaning and flushing of the condensate drain.
Identifies air/water flow problems as common causes for unit lockouts.
Fields for customer name, address, phone, and unit identification details.
Space to record unit make, model, refrigerant charge, compressor, and blower specs.
Sections to record entering/leaving air and fluid temperatures, flow, and pressures.
Fields to record auxiliary heat unit make, fuse size, voltage, and air temperatures.
Table detailing UPM board LED colors, blinks, and corresponding fault descriptions.
Troubleshooting steps for issues where the entire unit does not run.
Steps to diagnose issues when the blower runs but the compressor does not.
Diagnosing unit shutdown due to high pressure control issues.
Diagnosing unit shutdown due to low pressure control issues.
Troubleshooting causes for the unit short cycling.
Diagnosing and resolving issues with insufficient cooling or heating performance.
Provides resistance (ohms) values for compressor start and run windings by model.
Lists flash codes for Comfort Alert module and corresponding troubleshooting information.
Provides solutions for Comfort Alert flash codes 6, 7, 8, and 9.
Troubleshooting steps for HRP issues related to flow, temperature, and heat output.
Explains red LED status indications for SSA, including flashes and recovery mode.
Describes green LED status indications for SSA, related to power supply and idle state.
Instructions for mounting thermostat subbase, drilling, and wiring.
Details locations of detachable thermostat connectors based on motor type.
Explains jumper connections for 2-cool, 3-heat thermostats with W1/W2 and W2/EM.
Table showing operating temperatures and pressures for cooling mode by model and load.
Table showing operating temperatures and pressures for heating mode by model and load.
Provides airflow data for Constant Torque Motors at various static pressures.
Lists airflow data for Constant Airflow Motors (ECM) at various static pressures.
Illustrates the overall wiring of the unit, including components and connections.
Provides legends for standard/optional components and important wiring notes.
Diagrams for wiring harnesses related to constant torque motors.
Diagrams for wiring harnesses related to constant airflow ECM motors.
Illustrates and lists cabinet components for Vertical units.
Illustrates and lists blower assembly components for Vertical units.
Illustrates and lists refrigeration and electrical components for Vertical units.
Provides detailed illustrations of specific VT spare parts.
Continues detailed illustrations of specific VT spare parts.
Illustrates and lists cabinet components for Horizontal units.
Illustrates and lists blower assembly components for Horizontal units.
Illustrates and lists refrigeration components for Horizontal units.
Illustrates and lists panel components for Horizontal units.
Provides detailed illustrations of specific HZ spare parts.
Illustrates and lists cabinet components for Counter Flow units.
Illustrates and lists blower assembly components for Counter Flow units.
Illustrates and lists panel components for Counter Flow units.
Illustrates and lists refrigeration components for Counter Flow units.
Provides detailed illustrations of specific Counter Flow spare parts.
Provides dimensional data and illustrations for horizontal end blow configurations.
Provides dimensional data and illustrations for horizontal straight through configurations.
Shows hanging bracket location specifications for horizontal units.
Provides dimensional data and illustrations for Counter Flow units.
Provides dimensional data and illustrations for Vertical units.