Error H.01 – .14

Safety precautions:

1. If you smell gas, hear gas escaping, or suspect a leak: turn off the gas supply at the meter, do not operate electrical switches, ventilate the area and call the gas emergency number immediately. Evacuate if necessary.

2. If you suspect carbon monoxide (soot, yellow flame, headache, nausea, CO alarm): turn off the boiler, ventilate, and leave the property. Call a Gas Safe engineer and do not use the boiler until it is checked.

3. Isolate mains electrical power to the boiler before opening the casing or touching internal components. Do not attempt gas or burner repairs unless you are qualified.

Initial homeowner checks (safe to do):

1. Note the exact error code and whether it cleared itself or if the boiler is locked out. Try a single reset by pressing and holding the reset button for 3–5 seconds; watch if the code returns.

2. Check the system pressure on the boiler gauge. Correct operating pressure is typically around 1–1.5 bar when cold. If pressure is below 0.5 bar, the boiler may not circulate correctly — repressurise the system following the manufacturer instructions (use the filling loop) to about 1–1.5 bar.

3. Check that room thermostats, timers and programmer settings are calling for heat appropriately. Ensure radiator TRVs and the central heating flow/return isolation valves are open.

4. Feel the flow and return pipes at the boiler after it runs for a few minutes: they should both heat up and you should notice a temperature difference. If the flow pipe is hot and the return is not warming, circulation may be poor.

5. Bleed radiators to remove trapped air which can prevent circulation. After bleeding, recheck system pressure and repressurise if needed.

Specific diagnostic steps you can try (do not open the boiler):

1. Reset and observe: reset the boiler once. If the fault returns immediately or within a short period, make a note of when (during central heating, hot water call, or initial light-up) and any noises or smells.

2. Pump check (external observation only): with the boiler powered and calling for heat, carefully feel the pump casing and nearby pipes (do not touch rotating parts). You should detect vibration/warmth indicating the pump is running. If the pump is cold and you hear no activity, the pump may not be running or impeller could be seized — this requires an engineer.

3. Valve check: if your system has motorised zone valves, ensure they are moving when a call for heat is made. Manually open any isolation valves on the flow/return if accessible and safe to do so.

4. Flow/Return temperature check: if you have an IR thermometer or can safely touch pipes, check rates of temperature increase. A very rapid rise on flow with little change on return suggests no circulation.

5. Look for leaks or blockages: external pipework leaks or a blockage/scaling in the system can reduce flow. Visible leaks should be stopped and a professional contacted.

6. Check for error patterns: if the fault happens only on domestic hot water (DHW) or only on central heating, note that — it points to diverter valve (DHW) or primary circulation (CH) problems.

If the fault persists after basic checks:

1. Do not repeatedly reset and run the boiler if it is overheating — repeated dry-running risks damage.

2. Record the fault details to give to the engineer: exact error H.01 – .14, whether it occurred on heating or hot water, how often, any recent work on the system, system pressure reading, and whether reset temporarily cleared it.

3. Call a Gas Safe registered engineer. Tell them you have H.01–.14 maximum flow temperature / insufficient circulation fault on a Baxi 200/400 combi. Request checks including pump operation (and replacement if seized), motorised valve and diverter valve operation, flow and return NTC sensors and their wiring, heat exchanger condition (blockage or scale), and PCB diagnostics.

Why a professional is needed and what they will do:

1. The engineer will perform safe live electrical and gas checks, measure flow/return sensors with proper tools, test the pump under load, inspect and, if necessary, replace NTC temperature sensors, motorised valves, or the pump. They can also diagnose PCB or gas/air module faults if wiring or communication errors exist.

2. If the heat exchanger is badly scaled or blocked, or the gas/air unit or PCB is faulty, these are specialist repairs that require qualified replacement and testing.

3. If there are safety thermostat trips, they will test and reset or replace the safety devices as required and verify safe combustion and flue operation.

Final notes:

1. Temporary resets can clear a transient fault, but repeated H.01–.14 faults indicate an underlying circulation, sensor or control fault that should be fixed to avoid damage. 2. Do not attempt internal boiler repairs, gas valve or burner adjustments, or electrical component replacements yourself — always use a Gas Safe registered engineer.