What is the Alpha E-Tec 33 HB Hybrid Boiler?

The Alpha E-Tec 33 HB is a 28 kW indoor hybrid boiler unit with an A+++ ErP rating and OpenTherm compatibility. It functions as the internal component of a hybrid system, working alongside an external heat pump to provide efficient heating and hot water for domestic properties.

How do I register a Alpha E-Tec_33_HB_Hybrid_Boiler_Instructions with BoilerTag?

Scan the QR code on the BoilerTag sticker after installation to register a Alpha E-Tec 33 HB. Confirm the model details which pre-fill from the catalogue, then record the installation date and Gas Safe number. This creates a permanent, public service log for the appliance. The first 12 BoilerTag stickers are provided free to engineers. Order free BoilerTag stickers from the engineer dashboard.

What does fault code 01 mean on an Alpha E-Tec 33 HB?

Fault code 01 indicates an ignition failure where the flame is not detected. This is typically caused by issues with the gas supply, a faulty ignition electrode, a blocked flue, or a problem with the gas valve or PCB. Press the RESET button to clear the lockout once the cause is addressed.

How do I fix error 10 on an Alpha E-Tec 33 HB?

Error 10 signifies low primary system pressure. To resolve this, check the system for leaks and refill the primary circuit to 1.0 bar using the filling loop; if the fault persists, inspect the expansion vessel and pressure switch. The boiler will automatically reset once the correct pressure is detected.

Is the Alpha E-Tec 33 HB OpenTherm compatible?

Yes, the Alpha E-Tec 33 HB is OpenTherm compatible. This allows for bi-directional communication between the boiler and compatible thermostats like the Alpha Climatic or Smartech, enabling more precise modulation and improved energy efficiency compared to standard on/off controls.

What are the dimensions of the Alpha E-Tec 33 HB indoor unit?

The Alpha E-Tec 33 HB measures 712mm in height, 440mm in width, and 268mm in depth. It has a dry weight of 35.5 kg, making it suitable for standard kitchen cupboard or wall-mounted installations where space is limited.

How often does the Alpha E-Tec 33 HB require servicing?

The Alpha E-Tec 33 HB requires a professional service every 12 months. Key steps include checking the flue integrity, combustion circuit seals, gas inlet pressure, and overall combustion performance to maintain the warranty and ensure safe operation throughout the year.

What is the ErP rating of the Alpha E-Tec 33 HB?

The Alpha E-Tec 33 HB has an ErP rating of A+++ at a 35°C flow temperature. This high efficiency is achieved when the unit is integrated into a hybrid system using weather compensation and advanced controls, significantly reducing carbon emissions compared to standard boilers.

How do I reset an Alpha E-Tec 33 HB after a lockout?

Press the RESET button on the control panel to clear a lockout code. If the boiler reaches the maximum limit of five resets, the '08' fault code will display; you must then turn the power off and on again to clear the history and allow further operation.

What does fault code 60 indicate?

Fault code 60 indicates a pump fault, meaning the pump is stuck or there is an electrical failure. Engineers should check for a seized pump shaft, inspect the pump wiring, or replace the pump unit if it has failed electrically.

What does fault code 01 mean on the Alpha E-Tec 33 HB?

Ignition failure Likely causes: Gas supply; Check ignition/sensing electrode; Ignition generator or lead; Gas valve operation; Check PCB and wire connections; Flue restriction or blockage. Check gas supply, electrode, ignition generator, gas valve, PCB connections, and flue for blockages.

What does fault code 02 mean on the Alpha E-Tec 33 HB?

Overheat boiler lock out Likely causes: Pump or restricted flow problem; Blocked heat exchanger; Air in heat exchanger; Check external valves/circuit. Check pump, heat exchanger for blockages or air, and external valves.

What does fault code 03 mean on the Alpha E-Tec 33 HB?

High flue temperature Likely causes: Blocked or restricted primary flow; Heat exchanger air flow blocked; Flue restriction; Flue sensor fault; Air in primary heat exchanger. Check primary flow, heat exchanger air flow, flue restriction, and flue sensor.

What does fault code 04 mean on the Alpha E-Tec 33 HB?

Gas valve electrical connection fault Likely causes: Gas valve lead connection fault; Faulty gas valve; Faulty PCB. Check gas valve lead, gas valve, and PCB.

What does fault code 05 mean on the Alpha E-Tec 33 HB?

CH flow sensor fault Likely causes: Flow sensor wire connections or sensor faulty. Check flow sensor wiring and sensor resistance.

What does fault code 06 mean on the Alpha E-Tec 33 HB?

DHW sensor fault Likely causes: DHW sensor wiring connection or sensor faulty. Check DHW sensor wiring and sensor resistance.

What does fault code 08 mean on the Alpha E-Tec 33 HB?

Max. number of resets Likely causes: Multiple attempts to reset without clearing fault. Check fault history and replace PCB if necessary.

What does fault code 10 mean on the Alpha E-Tec 33 HB?

Primary system pressure low Likely causes: Check expansion vessel pressure (1 bar); Leak in system; Expansion relief valve operated; Primary pressure switch. Check expansion vessel, system for leaks, and pressure switch.

What does fault code 12 mean on the Alpha E-Tec 33 HB?

DHW inlet sensor fault Likely causes: Check sensor wiring and connections; Check sensor resistance. Check sensor wiring and resistance.

What does fault code 15 mean on the Alpha E-Tec 33 HB?

Incorrect configuration Likely causes: Inconsistency between settings and signals received from the PCB. Check the settings of the 'A' family parameters.

What does fault code 16 mean on the Alpha E-Tec 33 HB?

Fan fault Likely causes: Check fan wiring connections; Fan fault; PCB fault. Check fan wiring, fan, and PCB.

What does fault code 20 mean on the Alpha E-Tec 33 HB?

Flame sensing fault Likely causes: Flame detected but gas valve is not open. Check flame sensing electrode, lead, and PCB.

What does fault code 22 mean on the Alpha E-Tec 33 HB?

PCB fault Likely causes: Replace PCB. Replace the PCB.

What does fault code 23 mean on the Alpha E-Tec 33 HB?

Return sensor fault Likely causes: Check sensor wiring and connections; Check sensor resistance. Check return sensor wiring and resistance.

What does fault code 24 mean on the Alpha E-Tec 33 HB?

Control panel button fault Likely causes: Check for jammed control panel buttons; Check for jammed PCB buttons. Check for jammed buttons on the control panel or PCB.

What does fault code 25 mean on the Alpha E-Tec 33 HB?

PCB fault Likely causes: Replace PCB. Replace the PCB.

What does fault code 27 mean on the Alpha E-Tec 33 HB?

Primary circuit overheat Likely causes: Air in heat exchanger; Isolation/system valves closed; Check wiring/power to pump; Pump seized/blocked; Pump failed. Check for air, ensure valves are open, check pump wiring and operation.

What does fault code 29 mean on the Alpha E-Tec 33 HB?

Flue sensor fault Likely causes: Check sensor wiring and connections; Check sensor resistance. Check flue sensor wiring and resistance.

What does fault code 31 mean on the Alpha E-Tec 33 HB?

Loss of communication with external control Likely causes: Remote control or receiver connection wiring; Distance or interference of RF signal; Remote control or receiver fault. Check wiring, signal distance, and control unit.

What does fault code 37 mean on the Alpha E-Tec 33 HB?

Low supply voltage Likely causes: Check mains power supply; Check for bad cable connections etc. Check mains supply and cable connections.

Alpha E-Tec 33 HB Hybrid Boiler — Specs & Fault Codes

Engineer's overview

The Alpha E-Tec 33 HB serves as the internal thermal hub for Alpha’s hybrid heat pump range. As a 28 kW appliance, it manages the transition between fossil fuel and renewable energy sources to optimise efficiency. The unit is notably compact for its output, measuring 712mm in height, 440mm in width, and 268mm in depth, with a dry weight of 35.5 kg, facilitating wall-mounted installation in standard domestic settings.

Hydraulic performance is governed by a maximum operating pressure of 2.5 bar and a minimum of 0.5 bar. The system requires a minimum water flow rate of 1.5 litres per minute to maintain stable operation. For electrical integration, the unit operates on a standard 230V 50Hz single-phase supply, protected by a 3A MCB. Its maximum power consumption is rated at 0.105 kW.

Control logic is a core feature of the E-Tec 33 HB. It is OpenTherm ready and supports advanced controls such as the Alpha Climatic and Smartech systems. Integrated weather compensation allows the boiler to adjust its flow temperature based on external conditions, which is critical for maintaining the A+++ ErP efficiency rating at a 35°C flow temperature. The unit can reach a maximum flow temperature of 90°C when required by the heating circuit.

Maintenance and diagnostics are streamlined through a digital display. The unit reports specific fault codes, such as E01 for ignition failure or E10 for low primary system pressure. Engineers must perform an annual service every 12 months, which includes checking flue system integrity, combustion circuit seals, and gas inlet pressure at maximum rate. The sound power level is recorded at 55 dB, ensuring relatively quiet operation within the living space.

Installation requires specific clearances: 235mm above, 5mm at the sides, and 450mm at the front for service access. The appliance uses 22mm pipe connections for the primary circuit. While this manual focuses on the indoor boiler, the hybrid configuration allows for intelligent switching between the gas burner and the external heat pump unit based on demand and outdoor ambient temperatures, which can operate down to -5°C.

E-Tec 33 HB fault codes

Every fault code listed in the manufacturer brochure, with likely causes and engineer actions. Each code has a permalink — paste a URL like https://www.boilertag.com/heat-pumps/alpha/e-tec-33-hb-hybrid-boiler-instructions#fault-01 to jump straight to the entry.

Complete list of fault codes for this Alpha E-Tec 33 HB
Code	Meaning	Details
01Lockout	Ignition failure Show causes & actions Flame not detected during ignition sequence Likely causes Gas supply Check ignition/sensing electrode Ignition generator or lead Gas valve operation Check PCB and wire connections Flue restriction or blockage Engineer action Check gas supply, electrode, ignition generator, gas valve, PCB connections, and flue for blockages. Reset procedure Press the RESET button.	Details
02Lockout	Overheat boiler lock out Show causes & actions Overheat sensor has activated Likely causes Pump or restricted flow problem Blocked heat exchanger Air in heat exchanger Check external valves/circuit Engineer action Check pump, heat exchanger for blockages or air, and external valves. Reset procedure Press the RESET button.	Details
03	High flue temperature Show causes & actions Flue sensor intervention (flue temperature too high) Likely causes Blocked or restricted primary flow Heat exchanger air flow blocked Flue restriction Flue sensor fault Air in primary heat exchanger Engineer action Check primary flow, heat exchanger air flow, flue restriction, and flue sensor. Reset procedure Press the RESET button.	Details
04	Gas valve electrical connection fault Show causes & actions Gas valve wiring circuit fault detected Likely causes Gas valve lead connection fault Faulty gas valve Faulty PCB Engineer action Check gas valve lead, gas valve, and PCB. Reset procedure Press the RESET button.	Details
05	CH flow sensor fault Show causes & actions Incorrect flow sensor resistance value Likely causes Flow sensor wire connections or sensor faulty Engineer action Check flow sensor wiring and sensor resistance. Reset procedure Press the RESET button.	Details
06	DHW sensor fault Show causes & actions DHW sensor resistance value is incorrect Likely causes DHW sensor wiring connection or sensor faulty Engineer action Check DHW sensor wiring and sensor resistance. Reset procedure Press the RESET button.	Details
08Lockout	Max. number of resets Show causes & actions Maximum number of resets reached (5) Likely causes Multiple attempts to reset without clearing fault User action Refer to fault history codes (INFO menu d9), to reset by turning the boiler off and on. If it will not clear replace PCB. Engineer action Check fault history and replace PCB if necessary. Reset procedure Turn the boiler off and on.	Details
10	Primary system pressure low Show causes & actions Primary pressure switch has operated Likely causes Check expansion vessel pressure (1 bar) Leak in system Expansion relief valve operated Primary pressure switch User action Check system pressure on gauge and top up if necessary. Engineer action Check expansion vessel, system for leaks, and pressure switch. Reset procedure Refill system to 1.0 bar.	Details
12	DHW inlet sensor fault Show causes & actions Optional DHW inlet sensor resistance out of range Likely causes Check sensor wiring and connections Check sensor resistance Engineer action Check sensor wiring and resistance. Reset procedure Press the RESET button.	Details
15	Incorrect configuration Show causes & actions Incorrect hydraulic configuration Likely causes Inconsistency between settings and signals received from the PCB Engineer action Check the settings of the 'A' family parameters. Reset procedure Correct PCB parameters.	Details
16	Fan fault Show causes & actions Fan wiring fault or fan faulty Likely causes Check fan wiring connections Fan fault PCB fault Engineer action Check fan wiring, fan, and PCB. Reset procedure Press the RESET button.	Details
20	Flame sensing fault Show causes & actions False flame detection Likely causes Flame detected but gas valve is not open Engineer action Check flame sensing electrode, lead, and PCB. Reset procedure Press the RESET button.	Details
22	PCB fault Show causes & actions PCB software error Likely causes Replace PCB Engineer action Replace the PCB. Reset procedure Replace PCB.	Details
23	Return sensor fault Show causes & actions Return sensor resistance out of range Likely causes Check sensor wiring and connections Check sensor resistance Engineer action Check return sensor wiring and resistance. Reset procedure Press the RESET button.	Details
24	Control panel button fault Show causes & actions Control panel button stuck in the on position Likely causes Check for jammed control panel buttons Check for jammed PCB buttons Engineer action Check for jammed buttons on the control panel or PCB. Reset procedure Free jammed buttons.	Details
25	PCB fault Show causes & actions PCB fault - software error Likely causes Replace PCB Engineer action Replace the PCB. Reset procedure Replace PCB.	Details
27	Primary circuit overheat Show causes & actions Insufficient circulation in primary circuit causing overheating Likely causes Air in heat exchanger Isolation/system valves closed Check wiring/power to pump Pump seized/blocked Pump failed Engineer action Check for air, ensure valves are open, check pump wiring and operation. Reset procedure Press the RESET button.	Details
29	Flue sensor fault Show causes & actions Flue sensor resistance out of range Likely causes Check sensor wiring and connections Check sensor resistance Engineer action Check flue sensor wiring and resistance. Reset procedure Press the RESET button.	Details
31	Loss of communication with external control Show causes & actions Loss of connection between the boiler and Alpha Climatic control unit Likely causes Remote control or receiver connection wiring Distance or interference of RF signal Remote control or receiver fault User action Check batteries if using RF controller. Engineer action Check wiring, signal distance, and control unit. Reset procedure Restore communication link.	Details
37	Low supply voltage Show causes & actions Insufficient supply voltage to operate boiler Likely causes Check mains power supply Check for bad cable connections etc Engineer action Check mains supply and cable connections. Reset procedure Restore correct voltage.	Details
38	Loss of flame rectification Show causes & actions Flame detected but signal lost. Ignition retries after fan purge Likely causes Check flame sensing electrode and lead Check for flue gas recirculation Check the gas valve Check flue system and termination Check gas supply/working pressure Check/adjust combustion settings Check burner earth connection Engineer action Check electrode, flue system, gas valve, and gas pressure. Reset procedure Press the RESET button.	Details
43	Loss of flame rectification Show causes & actions Repeated loss of flame signal during operation Likely causes Flue exposed to high wind conditions Engineer action Check as above for error code 38. Reset procedure Press the RESET button.	Details
45	High ΔT Show causes & actions Sudden, unexpected increase in ΔT between flow and return sensors Likely causes Restricted water circulation Pump configuration Faulty return sensor Engineer action Ensure water circulation, check pump configuration and return sensor. Reset procedure Wait for ΔT to restore.	Details
47	Reduced burner output Show causes & actions Flue thermostat has sensed high flue gas temperature (110°C) Likely causes Air in heat exchanger Restricted primary flow Heat exchanger air flow blocked Flue restriction Flue sensor fault Pump fault Engineer action Check for air, flow restrictions, flue blockages, and pump operation. Reset procedure Wait for temperature to drop; if it continues to rise, E03 will display.	Details
51	Climatic RF communication fault Show causes & actions Error between communication of the Climatic transmitter and boiler receiver Likely causes Batteries require replacing User action Replace batteries in the control unit. Engineer action Check RF communication link. Reset procedure Replace batteries.	Details
60	Pump fault Show causes & actions The pump is stuck or there is an electrical pump fault Likely causes Seized pump shaft Pump wiring fault Faulty pump Engineer action Free pump shaft, check wiring, or replace pump. Reset procedure Press the RESET button.	Details
61	Air in the pump Show causes & actions Restricted CH flow due to air or a circuit restriction Likely causes Air in system Closed valves System pressure low User action Check system pressure and ensure valves are open. Engineer action Purge system of air and check for restrictions. Reset procedure Purge air from system.	Details
70	Return/flow sensor error Show causes & actions Return reading higher than flow Likely causes Possible wiring fault Sensors incorrectly fitted System blocked Engineer action Check sensor wiring, fitting, and system circulation. Reset procedure Press the RESET button.	Details
75	Return/flow sensor fault Show causes & actions Possible failure of one or both sensors Likely causes Check sensor wiring and connections Check sensor resistance Engineer action Check sensor wiring and resistance. Reset procedure Press the RESET button.	Details
76	Return/flow sensor fault Show causes & actions Possible failure of one or both sensors Likely causes Check sensor wiring and connections Check sensor resistance Engineer action Check sensor wiring and resistance. Reset procedure Press the RESET button.	Details
Sr	Service reminder Show causes & actions Service reminder count down has reached zero Likely causes Annual service interval reached User action Pressing the RESET button will clear the 'Sr' code for 24 hrs to allow the display to be read. Engineer action Perform annual service and reset the counter via parameter P6. Reset procedure 1. Enter parameter menu (password 69). 2. Set P6 to any value above zero and save. 3. Set P6 to 0 and save. 4. Set P6 to the number of months until next service (e.g., 12) and save.	Details
dot	Boiler completely turned off Show causes & actions Screen only shows a single dot to indicate boiler is completely off Likely causes Boiler switched to Off mode User action Press mode button for 2 seconds then release. Boiler display will return and you can select an operating mode. Reset procedure Press mode button for 2 seconds.	Details
Blank screen	Boiler fused blown Show causes & actions Fuse on main PCB blown Likely causes Incorrect power supply Seized or sticking pump Boiler component drawing excessive current Engineer action Check power supply, pump rotation, and individual components for excessive current. Reset procedure Replace fuse and address cause.	Details
Symbol with steady red light	Pump fault Show causes & actions Pump with UPM4 electronics ONLY indicating fault Likely causes Low power supply voltage Seized rotor Electrical fault Engineer action Check supply voltage, rotor rotation, and electrical integrity. Reset procedure Address electrical or mechanical fault.	Details

Common E-Tec 33 HB problems & troubleshooting

Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.

How to fix the E-Tec 33 HB ignition failureLockout

Engineer: Check gas supply, electrode, ignition generator, gas valve, PCB connections, and flue for blockages.

Triggered by fault code 01.

How to fix the E-Tec 33 HB overheat boiler lock outLockout

Engineer: Check pump, heat exchanger for blockages or air, and external valves.

Triggered by fault code 02.

How to fix the E-Tec 33 HB max. number of resetsLockout

User: Refer to fault history codes (INFO menu d9), to reset by turning the boiler off and on. If it will not clear replace PCB.

Engineer: Check fault history and replace PCB if necessary.

Triggered by fault code 08.

E-Tec 33 HB

E-Tec 33 HB at a glance

E-Tec 33 HB

E-Tec 33 HB at a glance

Register this Alpha E-Tec 33 HB on BoilerTag

E-Tec 33 HB data sheet

Engineer's overview

E-Tec 33 HB fault codes

Common E-Tec 33 HB problems & troubleshooting

How to fix the E-Tec 33 HB ignition failureLockout

How to fix the E-Tec 33 HB overheat boiler lock outLockout

How to fix the E-Tec 33 HB max. number of resetsLockout

How to fix the E-Tec 33 HB high flue temperature

E-Tec 33 HB FAQs

Every boiler brochure, free with BoilerTag

Working on a Alpha E-Tec 33 HB?

How to fix the E-Tec 33 HB gas valve electrical connection fault

Likely causes that trigger multiple E-Tec 33 HB fault codes

E-Tec 33 HB at a glance

E-Tec 33 HB at a glance

Register this Alpha E-Tec 33 HB on BoilerTag

E-Tec 33 HB data sheet

Engineer's overview

E-Tec 33 HB fault codes

Common E-Tec 33 HB problems & troubleshooting

How to fix the E-Tec 33 HB ignition failureLockout

How to fix the E-Tec 33 HB overheat boiler lock outLockout

How to fix the E-Tec 33 HB max. number of resetsLockout

How to fix the E-Tec 33 HB high flue temperature

E-Tec 33 HB FAQs

How do I fix error 10 on an Alpha E-Tec 33 HB?

Is the Alpha E-Tec 33 HB OpenTherm compatible?

What are the dimensions of the Alpha E-Tec 33 HB indoor unit?

How often does the Alpha E-Tec 33 HB require servicing?

What is the ErP rating of the Alpha E-Tec 33 HB?

How do I reset an Alpha E-Tec 33 HB after a lockout?

What does fault code 60 indicate?

Every boiler brochure, free with BoilerTag

Other Alpha heat pumps

Working on a Alpha E-Tec 33 HB?

How to fix the E-Tec 33 HB gas valve electrical connection fault

Likely causes that trigger multiple E-Tec 33 HB fault codes