Baxi
The Baxi 100 HE is a regular condensing boiler with a maximum central heating output of 32.61 kW, featuring a 90.9% seasonal efficiency and NOx Class 5 rating.
The Baxi 100 HE is a wall-hung, natural gas regular boiler designed for central heating systems in the UK. Identified by GC number 41 075 32, this condensing appliance offers a reliable heating solution. This reference page provides essential technical specifications, operational parameters, and detailed fault code diagnostics, serving as a resource for Gas Safe registered engineers and homeowners seeking comprehensive information on the Baxi 100 HE model.
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Full technical specifications extracted from the manufacturer brochure. Empty sections are hidden.
The boiler has two side water connections, the front connection being FLOW and the rear connection being RETURN.
All recirculatory water systems will be subject to corrosion unless an appropriate water treatment is applied. System additives - corrosion inhibitors and flushing agents/descalers should be suitable for aluminium and comply to BS7593 requirements. Failure to flush and add inhibitor to the system will invalidate the appliance warranty.
The Baxi 100 HE is a regular (heat-only) condensing boiler, specifically designed for wall-hung installation within UK domestic heating systems. Operating on natural gas, this appliance delivers a central heating output ranging from a minimum of 10.1 kW up to a maximum of 32.61 kW, making it suitable for a variety of property sizes. Its factory-set output is 22.0 kW, with adjustability up to 31.18 kW.
Engineers will note its compact physical dimensions: 600 mm in height, 390 mm in width, and 320 mm in depth, with a dry weight of 38.2 kg. The primary heat exchanger is constructed from aluminium. For system integration, the boiler features 28 mm flow and return pipe connections, a 15 mm gas pipe connection, and a 21.5 mm condensate drain. The flue outlet diameter is 110 mm, supporting horizontal, vertical, twin, and concentric flue types, with a maximum horizontal or vertical length of 4 metres, or 150 metres for twin flues.
In terms of efficiency, the Baxi 100 HE achieves a seasonal efficiency of 90.9% and is classified as NOx Class 5, indicating its low nitrogen oxide emissions. Electrical requirements are standard UK 230V, 50Hz, with a maximum power consumption of 80W and a 3A fuse rating. The boiler operates within a water pressure range of 0.1 to 3 bar, with a PRV setting of 3 bar and a water content of 2.6 litres.
Safety features include a boiler thermostat, safety thermostat, flow switch, electronic flame sensing, and a condensate blockage sensor. While frost protection is not integrated, the appliance is designed with multiple safeguards. Service intervals are recommended annually, with specific instructions for water quality, including pre-flushing requirements using agents like Betz-Dearborn Sentinel X300/X400 or Fernox Superfloc Universal Cleanser, and the use of inhibitors such as BETZ DEARBORN SENTINEL X100 or FERNOX COPAL to maintain warranty validity. The boiler is compatible with an Integral Electronic Twin Channel Timer Kit but is not Boiler Plus compliant. Comprehensive fault codes are provided for diagnostic purposes.
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/boilers/baxi/baxi-100he#fault-mains led off to jump straight to the entry.
| Code | Meaning | Details |
|---|---|---|
| Mains LED Off | Mains LED is off. Show causes & actionsLikely causes
Engineer action Replace 3A fuse; Check mains supply to boiler; Rectify wiring from mains input terminal block to control PCB; Replace control PCB; Replace transformer; Check for short circuits on control PCB and fan, replace fuse if OK; Rectify wiring from control PCB to interface PCB; Replace interface PCB. | Details |
| Mains LED Flashing | Mains LED is flashing. Show causes & actionsLikely causes
User action Switch on control knob. Engineer action Rectify wiring from control PCB to interface PCB; Replace control PCB; Replace interface PCB. | Details |
| Dry-fire LockoutLockout | Boiler is in dry-fire lockout (Lockout LED flashing 5 times a second). Show causes & actionsLikely causes
User action Fill system and switch pump on. Engineer action Replace control PCB; Replace flow switch. | Details |
| Safety LockoutLockout | Boiler is in safety lockout (Lockout LED flashing once a second). Show causes & actionsLikely causes
Engineer action Replace safety thermostat (black); Replace fan protection stat; Rectify wiring from control PCB to safety or fan protection thermostats; Replace flow temperature thermistor (red); Replace combustion box door seal; Replace control PCB. | Details |
| Thermistor Open Circuit | Flow temperature thermistor open circuit (Lockout LED flashing once every 4 seconds). Show causes & actionsLikely causes
Engineer action Replace thermistor; Rectify wiring from thermistor to logic PCB; Replace control PCB. | Details |
| Ignition LockoutLockout | Boiler is in ignition lockout (Lockout LED continuously on). Show causes & actionsLikely causes
Engineer action Rectify mains input polarity; Check for incorrect gas supply to boiler; Clear condensate blockage and dry sensors; Replace control PCB; Check 230V at control PCB connection to ignition PCB (M); Replace spark probe if damaged; Check 230V at ignition PCB connection to gas valve (O); Replace ignition PCB; Replace detection probe if damaged; Rectify wiring from ignition PCB to detection probe. Reset procedure Manually using the thermostat knob. | Details |
| No Fan | Fan is not running. Show causes & actionsLikely causes
Engineer action Replace flow temperature thermistor (red); Rectify wiring from control PCB to sensor; Replace fan; Replace control PCB. | Details |
| No Lockout ResetLockout | Boiler lockout cannot be reset. Show causes & actionsLikely causes
User action Allow flow temperature to drop below 60°C; Allow casing temperature to drop below 90°C; Ensure water in system and pump on. Engineer action Replace interface PCB; Rectify wiring from control PCB to interface PCB; Replace control PCB. | Details |
Patterns that group across the manufacturer's fault-code table. Each entry links to the full code listing further down the page.
User: Fill system and switch pump on.
Engineer: Replace control PCB; Replace flow switch.
Triggered by fault code Dry-fire Lockout.
Engineer: Replace safety thermostat (black); Replace fan protection stat; Rectify wiring from control PCB to safety or fan protection thermostats; Replace flow temperature thermistor (red); Replace combustion box door seal; Replace control PCB.
Triggered by fault code Safety Lockout.
Engineer: Rectify mains input polarity; Check for incorrect gas supply to boiler; Clear condensate blockage and dry sensors; Replace control PCB; Check 230V at control PCB connection to ignition PCB (M); Replace spark probe if damaged; Check 230V at ignition PCB connection to gas valve (O); Replace ignition PCB; Replace detection probe if damaged; Rectify wiring from ignition PCB to detection probe.
Common questions from engineers and homeowners about the Baxi 100 HE.
Parts referenced in the manufacturer brochure for routine service and repair.
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Specifications on this page are extracted from the manufacturer brochure. Always cross-check against the latest datasheet before commissioning or quoting. Last updated 27 April 2026.
Triggered by fault code Ignition Lockout.
User: Allow flow temperature to drop below 60°C; Allow casing temperature to drop below 90°C; Ensure water in system and pump on.
Engineer: Replace interface PCB; Rectify wiring from control PCB to interface PCB; Replace control PCB.
Triggered by fault code No Lockout Reset.
Engineer: Replace 3A fuse; Check mains supply to boiler; Rectify wiring from mains input terminal block to control PCB; Replace control PCB; Replace transformer; Check for short circuits on control PCB and fan, replace fuse if OK; Rectify wiring from control PCB to interface PCB; Replace interface PCB.
Triggered by fault code Mains LED Off.