Main Heating
Heat Only 15
Regular
15kW
2010-2016
ErP A
41 fault codes
<p>The Heat Only 15 is a combi boiler from Main Heating, available at 15kW output. Produced 2010-2016.</p>
Heat Only 15 Fault Codes 41
Code
Description
Severity
Type
E09
Gas Valve Connection Error
On Main Eco Compact boilers, code E09 indicates a fault in the gas valve connection cable.
High
Engineer
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E109
Pre-Circulation Fault
The boiler has detected insufficient circulation during its pre-circulation check.
Medium
Engineer
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E110
Overheat Lockout
The boiler has overheated and the safety thermostat has triggered.
High
Engineer
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E119
Low Water Pressure
System pressure has dropped below 0.5 bar. Main Heating boilers share the same fault code system…
Low
DIY
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E125
Primary Circuit Circulation Fault
Insufficient water circulation through the primary heating circuit.
Medium
Engineer
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E128
Loss of Flame During Operation
The boiler has lost its flame 12 times during operation, triggering a safety lockout.
High
Engineer
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E130
Flue Thermostat Tripped
The flue safety thermostat has activated due to excessively high flue temperatures.
High
Engineer
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E133
Ignition Failure / Frozen Condensate
The boiler has failed to ignite. Identical to Baxi E133 — Main Heating shares the BDR…
Medium
DIY
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E135
Gas Supply Interruption
The gas supply to the boiler has been interrupted.
Medium
DIY
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E154
Flow/Return Sensor Test Failure
The boiler's internal sensor cross-check test has failed.
Medium
Engineer
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E160
Fan Fault
The boiler fan has a fault — not running, running slowly, or speed sensor failure.
High
Engineer
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E168
PCB Lockout / Unspecified Fault
The PCB has detected an unspecified fault and locked out the boiler.
High
Engineer
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E20
CH NTC Sensor Fault
Central heating thermistor sensor fault on Main Heating boilers.
Medium
Engineer
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E270
Dry Fire Detected
The boiler has fired without adequate water circulation — a dry fire condition.
High
Engineer
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E28
Frozen Condensate / Flue Thermistor Fault
In cold weather, E28 on Main Heating boilers indicates a frozen condensate pipe. In warmer conditions,…
Medium
DIY
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E321
Hot Water NTC Fault (Eco Compact)
On Main Eco Compact boilers, E321 indicates a hot water thermistor fault.
Medium
Engineer
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E384
False Flame Detected
The boiler is detecting a flame signal when the gas valve should be closed.
High
Engineer
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E40
CH Return Sensor Error
Central heating return sensor has a fault on Main Eco Compact boilers.
Medium
Engineer
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E50
Hot Water NTC Fault
The domestic hot water temperature sensor has a fault on Main Heating boilers.
Medium
Engineer
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E60
Fan or Fan Wiring Fault
On some older Main boilers, E60 indicates a fan or fan wiring fault.
High
Engineer
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E83
Communication Error
A communication error between the boiler PCB and external controls or room controller.
Medium
Engineer
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