Immergas boiler error 27: causes and safe checks

Code 27 indicates insufficient water circulation in Immergas boilers such as the Victrix Tera 24-28 and Eolo Superior 21/24/27. The appliance detects that water in the primary circuit is not carrying heat away properly and may shut down to protect itself. This does not automatically mean the pump needs replacing: trapped air or a restriction may also be responsible. Without opening the boiler, you can read the pressure, observe the radiators and check accessible controls. If the warning persists, a qualified technician needs to investigate.

If you have a problem with your boiler, you can use our free error code finder. There you can identify errors and find clear guidance on how to address them.

The water is not moving as the boiler needs it to

Combustion produces heat, but that heat needs to leave the heat exchanger and travel through the circuit. The circulating pump keeps the water moving to make this possible. When flow is insufficient, the temperature inside the appliance can rise quickly even while the radiators remain cold. The warning therefore describes a problem moving heat around, rather than necessarily an inability to generate it.

This distinction explains a seemingly contradictory situation: the display shows a high temperature while the home fails to warm up. It is not conclusive evidence of a faulty pump, but it is a useful observation for diagnosis. Water can struggle to circulate for several reasons, and the same shutdown can have different causes that require different checks.

Pressure does not tell the whole story either. The gauge indicates circuit pressure, not how much water passes through the heat exchanger at any given moment. An apparently correct reading does not prove circulation is adequate. Likewise, low pressure needs attention, but pressure and flow are not interchangeable. Confusing them can lead to unnecessary topping up when the actual problem lies elsewhere.

The exact model determines how the warning should be read

The reference documentation for the Victrix Tera 24-28 and Eolo Superior 21/24/27 associates 27 with insufficient circulation. That agreement helps guide the investigation, but it does not make all Immergas codes universal. The manual for the specific model determines what the warning means, how the shutdown behaves and which reset instructions are available to the user.

Some generic code lists describe 27 as a communication fault with the remote panel. That interpretation conflicts with the documentation cited for these ranges and should not be used to diagnose them. On the Eolo Superior models mentioned, 31 means the Control Amigo Remoto is incompatible. The distinction matters: a hydraulic problem is not a communication fault simply because another online table suggests otherwise.

Identify the appliance using the complete model designation in its paperwork or on a label visible without removing anything. The product family name may not be enough if different versions exist. Screen colour should not be the main guide either: light indications vary, and the displayed number and exact model provide a firmer reference than a generic description of the display.

Related codes help keep different faults separate

Other warnings may appear before or after 27. Recording that sequence helps explain what happened, but it does not make the codes interchangeable. The following table covers codes for the Eolo Superior 21/24/27 included in the reference documentation. It should not automatically be applied to a Victrix or another range, even where some numbers match.

The table separates a detected condition from a component proven to be faulty. Overtemperature protection does not prove the thermostat is broken, just as a circulation warning does not confirm an unusable pump. Keeping a photograph of the display and explaining which code appeared first is more useful than trying a different repair for every number.

The pump is a possibility, not a confirmed diagnosis

A stuck or faulty pump can prevent water from travelling through the circuit normally. In that situation, the boiler produces heat it cannot remove at the required rate. However, noise, vibration or their absence cannot reliably establish the pump’s condition from outside. Checking the circulator is a technician’s job: they need to distinguish a blockage or seizure from a failure that justifies replacement.

A closed or defective valve can also restrict flow. Context provides clues: a problem that starts after work on the installation calls for a different investigation from one that appears without any known changes. Users can observe familiar radiator controls, but should not turn unidentified valves beneath the boiler or force mechanisms that resist movement.

Trapped air is another possibility. Gurgling or uneven heat distribution may be consistent with air in the system, although neither proves it on its own. The work needed depends on where air has collected and how the installation is arranged. Opening boiler vents or removing plugs can expose hot, pressurised water: this is not a harmless household check.

For the same reason, do not try to free the pump shaft with a screwdriver or remove its plug. This is internal work that can expose you to hot water and electrical components. Informal instructions do not change that boundary. Removing the casing to find the fault falls outside safe user checks.

The pressure reading provides clues, not permission to top up

Reading the pressure gauge or digital indicator is an accessible check. Record the value and whether the boiler was cold or had been running, because temperature affects pressure. Then compare it with the manufacturer’s instructions for that appliance. A number found in a generic table should not be treated as the required pressure for every model.

If the reading is outside the range specified in the manual, report that to the professional. Do not open the filling valve as an automatic response to 27: adding water will not free a pump or remove an obstruction. Pressure that keeps falling also needs its cause investigated. Repeated topping up can conceal the problem rather than solve it.

External observation can provide useful information too. A damp patch beneath the appliance, visible dripping or leaks near radiators should be recorded without taking joints apart or trying to tighten them. If there is an active leak or water near electrical components, stop using the boiler. Leak investigation and any work on the pressurised water circuit belong to an authorised professional.

The radiators help show how the problem developed

Heat distribution helps describe the fault more accurately. All radiators remaining cold is different from one radiator heating less than the others. An immediate shutdown is also different from one that occurs after several minutes. These observations do not replace measurements, but they help reconstruct what happened before the shutdown without touching internal components.

If all radiator controls have been closed, the available path for water may have changed; the consequences depend on the installation design and its regulating components. You can check whether familiar user controls have accidentally been left closed, without forcing them. There is no need to change balancing or technical settings to carry out a visual check of familiar controls.

Recent changes are worth recording as well. Replacing a radiator, carrying out maintenance or draining part of the circuit may guide the investigation towards trapped air or an altered hydraulic configuration. This does not prove the most recent work was done incorrectly, but it adds context. A clear timeline is more useful than claiming the pump has failed without a professional assessment.

A successful reset does not prove the fault is repaired

If the manual allows the user to reset this warning, one attempt can be made using the designated control, provided there are no leaks or other abnormal signs. Follow the instructions for that model rather than borrowing button timings from another boiler. Some appliances have a dedicated button and others use a selector function; there is no universal reset sequence across the brand.

If the code disappears, that only shows the appliance has accepted a return to operation at that moment. It does not confirm that the cause has been corrected or that the electronics had made an incorrect reading. If it shuts down again when heating or hot water is requested, do not keep resetting it. A returning warning needs diagnosis, especially if the temperature rises quickly while the radiators receive little heat.

Repeatedly switching the power off and on to clear the problem is not advisable either. The shutdown is a protective measure, not an obstacle to work around until the appliance starts. If there is banging, loud noise or a leak, stop using it and arrange an inspection. Forcing repeated operation is not a useful test of how serious the fault may be.

Hot water also depends on the primary circuit

In a combination boiler, water in the primary circuit helps produce domestic hot water through the relevant heat exchange system. It should not be confused with the water coming out of the tap: they follow separate paths. Describing the warning as a heating problem therefore does not establish that using the shower is independent of the fault.

Tell the technician if the shutdown happens only when a tap is opened, or only when central heating is requested. That difference may help establish the conditions in which circulation fails, but it does not justify running the appliance in the other mode as a temporary solution. A temporary absence of the code does not guarantee that the circuit works correctly in every operating condition.

The cautious approach is to stop repeated attempts when the fault returns and follow the manual’s instructions for taking the appliance out of use. Needing hot water does not change the safety limits. An accurate account of when it shuts down is preferable to trying successive temperature settings or demands in search of a combination that avoids the protection.

A repair quote should start with a confirmed cause

The code cannot provide a reliable repair price. Correcting an accessible restriction does not cost the same as replacing a circulator, and a failed reset does not establish that a new electronic board is needed. Before approving a replacement part, the diagnosis should explain which finding justifies replacement and which other possible causes have been ruled out.

A useful quote separates the call-out or diagnostic charge, labour and materials, and states whether the visit is payable if the repair is declined. Do not assume that charge will be deducted later: that depends on the terms of the service you book. Knowing exactly what the quote includes avoids comparing a partial figure with one covering the whole job.

The code alone offers little basis for deciding whether to repair or replace the boiler. The confirmed fault, overall condition, history of problems and spare-part availability matter more. A localised hydraulic issue has different implications from several significant faults occurring together. Compare the complete cost of each option, rather than making the decision out of concern at seeing the boiler shut down.

If the appliance may still have warranty cover, check the terms before commissioning work or buying parts. It is not accurate to say that every user check automatically invalidates cover, but neither should internal work be assumed to have no consequences. Keeping the paperwork and avoiding dismantling allows you to check the cover without altering the appliance or adding unnecessary risks.

A clear fault history prevents guesswork with replacement parts

When 27 persists, the professional needs to identify the boiler and check water circulation, pump response and any restrictions or trapped air. Temperature readings and control operation also form part of the diagnosis where appropriate. The aim is not to replace the component most often mentioned online, but to establish why heat is not being carried away properly.

Useful information can be gathered without opening anything: the complete model, a photograph of the code, the observed pressure and the circumstances in which it appears. Recent work, noises, visible leaks or differences between heating and hot water operation help reconstruct the fault. There is no need to prolong testing to collect information; observations made before the shutdown already matter.

For the ranges discussed, the core meaning of 27 is clear: circulation is insufficient. What remains to be established is the specific cause and the work required. Keeping those separate avoids buying a pump without a diagnosis, topping up without a reason or persisting with resets. The user’s role is limited to observation and intended user controls; internal repairs belong to a qualified technician.