Biasi ER14 Fault Code: Causes, Fixes & Repair Costs
What does the Biasi ER14 fault code mean?
The ER14 fault code on a Biasi boiler signals that the control board has detected either a failure in water circulation through the primary circuit, or that the primary flow temperature has exceeded 105°C. In plain terms, the boiler cannot confirm that water is moving around the system at an adequate rate, or it has become dangerously hot. As a safety measure, the boiler will typically go into lockout — shutting itself down to prevent further damage. Avoid repeatedly resetting the boiler until the underlying problem has been identified and resolved.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Seized or failing circulation pump Common
The most frequent trigger for ER14 is a pump that has seized up, is running intermittently, or has failed entirely. When water stops moving through the primary circuit, the boiler's flow sensor or temperature sensors quickly detect the problem and lock the boiler out. Pumps in older or infrequently serviced systems are particularly prone to seizing, especially if magnetite sludge has built up around the impeller.
- Airlock trapped in the pump or pipework Common
A pocket of air lodged in the pump body or the primary pipework can prevent adequate water movement, mimicking a full pump failure. This is more common after system work has been carried out, after the system pressure has dropped very low, or at the start of the heating season after a long period of dormancy. An engineer can bleed the pump via its bleed screw to release the trapped air.
- Magnetite sludge or limescale blockage Common
Heating sludge — the dark, muddy by-product of internal corrosion in radiators, valves, and pipework — accumulates over time and can restrict or block the pump impeller and heat exchanger passages. In hard water areas, limescale deposits compound the problem by coating internal surfaces and narrowing flow paths. Either condition can reduce circulation enough to trigger ER14, and may also cause the primary temperature to spike towards or beyond 105°C.
- Incorrect pump speed setting Sometimes
Biasi boilers require the pump to operate at the correct speed setting for the size and layout of the heating system. If the speed is set too low — often the case after a new installation or pump replacement — water moves through the circuit too slowly, causing poor heat distribution and potentially triggering the overtemperature protection that contributes to ER14.
- Pump wiring or PCB communication fault Sometimes
The boiler's PCB continuously monitors pump operation. If the wiring between the PCB and the pump is corroded, loose, or damaged — possibly by water ingress — the PCB may lose the signal it expects from the pump and raise ER14 even if the pump itself is mechanically sound. A faulty PCB may also send incorrect signals, producing the same result.
- Pump seal leak causing low system pressure Sometimes
A leaking pump seal can cause a slow but progressive drop in system pressure. As pressure falls, circulation efficiency drops with it, and the boiler may struggle to confirm adequate flow. The resulting strain on the pump can accelerate wear and eventually lead to ER14. Look for damp patches or dried limescale residue around the pump body.
- Blocked or restricted heat exchanger Rare
A partially blocked primary heat exchanger restricts the volume of water that can flow through it, causing localised temperature spikes. If the primary flow temperature climbs above 105°C — the boiler's safety threshold — ER14 can be triggered even when the pump itself is operating correctly. This is more common in systems without a magnetic filter and in hard water regions.
How to fix it
- Check that the gas supply to your home is working DIY safe
Confirm that other gas appliances such as a hob or gas fire are operating normally. If there is no gas supply to the property, contact your gas supplier before going any further.
- Check and restore system pressure if it has dropped below 1 bar DIY safe
Look at the pressure gauge on the boiler — it should sit between 1 and 1.5 bar when the system is cold. If it has dropped below 1 bar, top it up carefully using the filling loop (typically the braided hose or lever valve beneath or near the boiler) until the gauge reads around 1.2 bar, then close the filling loop fully. Refer to your boiler manual for the exact filling loop location on your model. If pressure is already correct, move on.
- Attempt a single boiler reset DIY safe
Once you have checked pressure and the gas supply is confirmed, press and hold the reset button (usually marked with a flame or reset symbol) for around three seconds. Allow the boiler two to three minutes to restart. If it locks out again immediately, do not continue resetting — repeated resets without resolving the cause can damage components further.
- Look for visible leaks around the pump area DIY safe
With the boiler off and cool, inspect the area around the pump body for any signs of dripping water, damp patches, or dried white limescale residue that may indicate a slow seal leak. Do not attempt to tighten, remove, or replace any components — simply note what you find and report it to the engineer.
- Do not attempt to bleed, dismantle, or replace the pump yourself Gas Safe engineer
Bleeding the pump bleed screw, adjusting pump speed settings, removing the pump, and testing electrical connections all require the system to be safely isolated and the work carried out by a competent person. Incorrect handling risks water damage, electric shock, and loss of system integrity.
- Do not attempt to inspect or replace the PCB or wiring Gas Safe engineer
Testing the PCB and pump wiring with a multimeter, repairing damaged connections, and replacing the PCB are all tasks for a Gas Safe registered engineer. These components involve mains voltage and must only be handled by a qualified professional.
- Call a Gas Safe registered engineer to diagnose and repair the fault Gas Safe engineer
An engineer will carry out a systematic diagnosis: testing pump operation and electrical supply with a multimeter, bleeding the pump if an airlock is suspected, checking pump speed settings, inspecting for sludge or limescale, and assessing the heat exchanger and PCB. Depending on findings, repairs may include pump bleeding, a system flush or Powerflush, pump replacement, or PCB repair. Always ask to see the engineer's Gas Safe registration card before work begins.
Parts you may need
- Central heating circulation pump (e.g. Grundfos UPS2 or equivalent) · from £65
- Pump capacitor · from £12
- PCB (printed circuit board) · from £180
- Magnetic system filter (e.g. Fernox TF1 or Adey MagnaClean) · from £55
- Pump wiring harness · from £25
- Heat exchanger (primary) · from £120
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £120–£350, depending on the underlying cause.
Frequently asked questions
Can I keep resetting my Biasi boiler to clear the ER14 code?
It is best to limit resets to one attempt. If the boiler locks out again shortly after a reset, there is an active fault that resetting will not cure — and repeatedly forcing restarts can put additional stress on the pump, PCB, and other components. Wait until a Gas Safe engineer has diagnosed and fixed the underlying problem before resetting again.
How much does it cost to fix a Biasi ER14 fault in the UK?
Most homeowners with this fault code pay between £120 and £350, depending on what the engineer finds. Bleeding an airlock or correcting the pump speed setting will be at the lower end — broadly just a call-out and labour. A pump replacement including a quality part such as a Grundfos pump typically comes to around £200–£280 all in. If the PCB turns out to be faulty, expect to pay £350–£500 or more, as the board itself is expensive. A primary heat exchanger replacement is a bigger job still and can exceed £600, though this is an uncommon outcome for ER14.
Is ER14 always a pump failure, or could something else be causing it?
ER14 can be triggered by any condition that prevents adequate water flow or causes the primary temperature to exceed 105°C. So while a failed or seized pump is the most common cause, the code can also appear because of an airlock, a sludge or limescale blockage in the pump or heat exchanger, a leak dropping system pressure, a wiring fault between the pump and PCB, or even an incorrect pump speed setting. A Gas Safe engineer will work through these possibilities systematically rather than assuming the pump needs replacing straight away.
How can I reduce the chances of ER14 happening again?
There are a few practical steps worth taking after the repair. Having a magnetic filter fitted to the central heating circuit (if one is not already present) captures sludge before it reaches the pump and heat exchanger. Getting an annual boiler service means an engineer checks pump operation, system pressure, and water quality every year, catching problems early. Bleeding radiators at the start of each heating season releases trapped air before it can cause an airlock. And if your Biasi boiler is still within its 5–7 year manufacturer warranty, contact Biasi directly before paying for repairs — the fault may be covered.