Baxi code H.01.18 means no water circulation (temporary). Baxi lists this wording for applicable Combi 2 and System 2 boilers. The controls have detected that heating water is not moving as expected and have treated the interruption as temporary.
A temporary code can clear when conditions return to normal, but it should not be ignored if it returns. The display does not identify one failed part, and it is not an invitation to open the boiler, free a pump or alter valves.
What does Baxi H.01.18 mean?
Heating water must circulate through the boiler so heat can be carried into the system. H.01.18 appears when the boiler temporarily cannot confirm the expected circulation. Depending on the model and operating condition, the appliance may pause while protecting itself.
The word “temporary” describes how Baxi categorises the message. It does not guarantee that the issue has fixed itself. If the code appears repeatedly or heating and hot water remain unreliable, arrange a qualified repair.
Which Baxi boilers use H.01.18?
Baxi places H.01.18 in its Combi & System 2 error-code group. The current list includes Baxi 200, 400, 600 and 800 Combi 2 boilers, the Assure 500 Combi 2, and the Baxi 600, 800 and Assure 500 System 2 ranges.
Check the exact model name visible on your appliance and use its matching user guide. Other Baxi ranges can use different controls and codes, and a similar-looking message on another make may have a different meaning.
How is H.01.18 different from E.01.17?
Baxi defines H.01.18 as no water circulation (temporary). It separately defines E.01.17 as no water circulation (permanent). Both concern the movement of heating water, but the boiler has categorised the duration or persistence differently.
If H.01.18 clears once, monitor the boiler. If it comes back, do not keep treating it as a harmless pause. A recurring temporary circulation code can still interrupt heating or hot water and needs professional attention.
What symptoms might you notice?
The boiler may pause shortly after starting, radiators may remain cool, or hot water may be interrupted. The message may disappear and later return. You might also notice that some radiators warm while others do not.
These are useful observations, not proof of a cause. H.01.18 does not automatically mean the pump has failed, and the code should not be used to decide which part to replace.
What can you safely check?
Keep the boiler closed and make only external observations:
- Write down the complete code H.01.18.
- Note whether heating, hot water or both were being requested.
- Record how long the boiler ran before the message appeared.
- Look at the normal pressure display or external gauge and note the reading.
- Observe which radiators are warm or cold without removing fittings.
- Check for visible water or staining around accessible pipework.
- Confirm the exact model name from the outside of the boiler.
Do not assume radiator bleeding is the cure for this code. Do not repeatedly top up pressure, attempt to turn a pump, alter a bypass, remove panels or operate unfamiliar valves.
Should you reset H.01.18?
Consult the user guide for your exact Baxi model. If it permits a homeowner reset, one careful attempt is reasonable when there is no gas smell, carbon-monoxide warning, visible leak near electrics or sign of overheating.
If the message remains or returns, stop resetting and arrange repair. Repeated resets can hide the timing of the circulation interruption without correcting whatever is causing it.
Can you keep using the boiler?
If H.01.18 clears in accordance with the correct user guide and normal operation returns, continue to monitor the display. If the message recurs, heating or hot water becomes unreliable, or the boiler progresses to a permanent circulation fault, book an engineer.
Do not try to force a boiler to run while it is pausing for protection. If temporary electric heaters are needed, use them according to their instructions, keep them clear of furnishings and never leave them unattended.
What will an engineer check?
A suitably qualified Gas Safe registered engineer will confirm the exact model, pressure and fault history, then use Baxi’s service information to test circulation safely. Several hydraulic, sensing or control conditions can produce an unexpected circulation result, so the displayed code is not a complete repair conclusion.
Internal pumps, sensors, wiring, valves and hydraulic components must remain untouched by the homeowner. Accurate notes about when the code appears can help the repair visit begin efficiently.
What should you report when booking?
Provide the full H.01.18 code, the model name, the visible pressure reading and whether the interruption occurred during heating or hot-water demand. Mention whether the message cleared by itself or returned after one permitted reset.
For other manufacturer-specific messages, use our boiler help guides. Always match information to the make and exact model on the appliance.
Does Baxi code H.01.18 keep returning?
Book Incredaboil’s fixed-price boiler repair for a clear price and an engineer visit focused on fixing the circulation fault.
Quick answers about Baxi H.01.18
What does H.01.18 mean on a Baxi boiler?
It means no water circulation, categorised by Baxi as temporary on the applicable Combi 2 and System 2 ranges.
Is H.01.18 the same as E.01.17?
No. H.01.18 is temporary no circulation; E.01.17 is the permanent no-circulation fault.
Can I fix H.01.18 by bleeding radiators?
Do not assume that bleeding is the cure. Note the visible symptoms and follow only the exact user guide. A recurring code needs qualified repair.
Can I reset Baxi H.01.18?
If your exact model guide permits it, make one reset attempt. Stop if the code returns and arrange professional attention.