Geminox Boiler Repairs
Experienced Geminox Boiler Repairs specialists
Available 24 hours a day, 7 days a week
Insurance approved
All parts guaranteed for a year
Fully Gas Safe trained engineers
Geminox Boiler Repairs London
Gas Safe registered engineers • 24/7 call handling • London wide
Call Now: 0203 868 6251
Tell us the fault code and model. We will advise the safest next step.
Common Geminox models we repair include THRi, Megalisthe, and Geminox condensing boilers, with frequent calls for ignition lockout, low pressure, overheat, and circulation faults.
We fix Geminox boiler fault codes, no heating, no hot water, lockout, leaking, and low pressure across London.
We also offer boiler servicing and boiler installation across London.
Quick Navigation
Safety First
Smell gas? Turn off the gas supply at the meter if it is safe to do so. Open windows. Leave the property. Call the National Gas Emergency Service on 0800 111 999. Do not use switches, and do not use naked flames.
CO alarm sounding? Open windows immediately. Leave the property. Call 999. Do not re-enter until cleared by emergency services.
Boiler leaking heavily? Turn off the boiler at the controls. If safe, turn off the water supply. Call an engineer.
Quick Checks Before You Call
Before calling an engineer, these safe checks may resolve simple issues with your Geminox boiler.
Check the gas supply
Is gas working at other appliances in your home? If not, check your meter and any prepayment credit.
Check the pressure gauge
Pressure should read around 1.0 to 1.5 bar when cold. If below 1 bar, you may need to repressurise using the filling loop.
Check the thermostat
Is the room thermostat set above current room temperature? Are the batteries working?
Check the timer or programmer
Is the heating scheduled to be on? Check the clock is set correctly.
Try a single reset
Locate the reset button on your Geminox boiler. Press once and wait. If the fault returns, do not keep resetting. Call an engineer.
Check the condensate pipe
In cold weather, the external condensate pipe can freeze. Look for a white plastic pipe exiting through an outside wall. If frozen, pour warm water over it gently.
Geminox Fault Codes
Note: Geminox fault codes vary by model and controller. If your code is not listed here, call us with the exact code and model and we will advise the safest next step.
Common Geminox fault types and what to do
| Code / Message |
What It Means |
What To Do |
| Ignition / Lockout |
Boiler cannot establish a stable flame |
Check gas supply and whether other gas appliances work. In freezing weather, check condensate pipe. Reset once. If it returns, call an engineer. |
| Low Pressure |
System pressure below minimum operating level |
Top up to 1.0 to 1.5 bar. If it drops again within days, call an engineer. |
| Overheat |
Boiler has shut down for safety due to high temperature |
Do not keep resetting. Call an engineer to check circulation, sensors and safety controls. |
| No Circulation |
Poor flow through the system or pump related issue |
Check radiators are warming evenly. If flow seems poor or it repeats, call an engineer. |
| Fan / Airflow |
Airflow safety fault or fan proving issue |
Call an engineer. Do not attempt DIY on flues or remove the casing. |
| Sensor / Control |
Temperature sensor or control issue |
Reset once. If it returns, call an engineer for safe testing. |
Most Searched Geminox Problems
If you are seeing a lockout, loss of hot water, or your Geminox boiler keeps resetting, tell us the fault code and model and we will confirm the safest next step.
Ignition lockout
Ignition lockout is the most common Geminox fault. The boiler tries to ignite but cannot establish a stable flame. Common causes include gas supply issues, a faulty ignition electrode, or a blocked condensate pipe in winter. Check gas is on elsewhere in the home. Try one reset. If the lockout returns, stop and call an engineer.
Low pressure
If your Geminox shows a low pressure warning, system pressure has dropped below the minimum operating level. Top up via the filling loop to around 1.0 to 1.5 bar when cold. If pressure drops again within days, there may be a leak in the system or a failing expansion vessel. Call an engineer to find the cause.
Overheat protection
If your Geminox has shut down due to overheat, the boiler has reached a high temperature and locked out for safety. This can indicate a circulation problem, pump failure, or blocked heat exchanger. Do not keep resetting. Call an engineer to check the system.
No hot water but heating works
On Geminox combi boilers, you may get heating but no hot water, or the reverse. This often points to a diverter valve issue. The diverter valve directs hot water between taps and radiators. When it wears or sticks, hot water delivery becomes unreliable. Call an engineer for diagnosis.
Why Geminox Boilers Develop Faults
Geminox is a European manufacturer with a range of condensing boilers. Here is what we commonly see.
Ignition electrode wear
Ignition faults can occur when the ignition electrode wears or becomes coated with carbon. Condensate blockages in winter can also contribute to repeated lockouts.
Low pressure and expansion vessel faults
Low pressure faults often point to a failing expansion vessel or a weeping pressure relief valve. The expansion vessel absorbs pressure changes as water heats and cools. If the diaphragm fails or the air charge is lost, pressure drops can occur.
Circulation and pump issues
No circulation faults can indicate poor flow through the system. This may be caused by a failing pump, sludge buildup, or closed radiator valves. A powerflush may help restore flow.
Fan and airflow faults
Fan faults prevent safe combustion and flue gas extraction. The boiler will lock out for safety. Causes include fan motor failure, wiring faults, or flue blockages.
Diverter valve on combi boilers
The diverter valve directs hot water between your taps and radiators. When it wears or sticks, you may get heating but no hot water, or the reverse.
Geminox Models We Repair
We repair Geminox combi, system, and regular boilers in London, including:
THRi range: THRi condensing boilers
Megalisthe range: Megalisthe condensing models
Condensing range: Various Geminox condensing units
Other models: Older Geminox boilers
Geminox parts can be more specialist than mainstream UK brands. We check availability before attending and advise honestly if repair is not viable or cost effective.
Repair or Replace Your Geminox Boiler?
We help you decide based on age, reliability, and parts availability.
Repair makes sense when
- Boiler is under 10 years old
- This is the first major fault
- Parts are readily available
- Boiler has been regularly serviced
Replacement may be better when
- Boiler is 12 to 15 years old or more
- You have had multiple breakdowns recently
- Parts are obsolete or hard to source
- The boiler is undersized for the property
- Energy bills are higher than expected for the property size
Our engineers give honest assessments. We focus on safety and reliability, not pushing unnecessary replacements.
Geminox Boiler Servicing
Annual servicing reduces breakdown risk and keeps your Geminox boiler running efficiently. See Boiler servicing London.
Landlords and Letting Agents
We provide boiler repairs and gas safety certification for landlords across London. See Landlord gas safety certificate (CP12).
Geminox Repairs Across London
London wide coverage for Geminox boiler repairs. Book an engineer or view our London areas we cover.
Have your postcode and fault code ready and we will confirm the quickest appointment slot.
Other Boiler Brands We Repair
Worcester • Vaillant • Ideal • Baxi • Glow-worm • Viessmann • Potterton • Vokera • Alpha • Ferroli
View all brands
Geminox Boiler Repair FAQs
How quickly can you attend for a Geminox breakdown?
We offer same day attendance where slots are available. For no heating or hot water, we prioritise urgent breakdowns. Call our 24/7 line and we will advise availability.
Do you carry Geminox parts?
Geminox parts can be more specialist than mainstream UK brands. We check availability and source parts as quickly as possible. For common faults, we often have compatible components available.
Is it safe to reset my Geminox boiler?
Try one reset. If the fault returns after resetting, stop and call an engineer. Do not keep resetting, especially for overheat faults.
How much does a Geminox boiler repair cost?
Costs vary depending on the fault and parts required. We diagnose first and quote before any repair work begins.
Related Services
Speak to Our Team
For safe next steps, call now.
Call 0203 868 6251 | Book an Engineer
Gas Safe registered • 24/7 call handling • Quote before work
