Ariston Boiler Repairs
Experienced Ariston 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
Ariston 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 Ariston models we repair include E-Combi, E-System, Clas, and Genus, with frequent calls for codes 501, 108, 103, and 104.
We fix Ariston 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 Ariston 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 Ariston 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.
Ariston Fault Codes
Note: Ariston fault codes can vary by model and generation. If your code is not listed, call us with the exact code and model and we will advise the safest next step.
Common Ariston fault codes and what to do
| Code |
What It Means |
What To Do |
| 501 |
Ignition failure or no flame detected |
Check gas supply and whether other gas appliances work. In freezing weather, check condensate pipe. If still locked out, call an engineer. |
| 108 |
Low system pressure |
Top up to 1.0 to 1.5 bar. If it drops again within days, call an engineer. |
| 103 |
Circulation issue or poor flow detected |
Check radiators are warming evenly. If flow seems poor or it returns, call an engineer. |
| 104 |
Overheat protection triggered |
Do not keep resetting. Call an engineer for safe checks and testing. |
| 607 |
Fan fault or fan not detected |
Call an engineer. Do not remove the casing. |
| 5P1 |
Flame signal issue (model dependent) |
Reset once. If it returns, call an engineer. |
Most Searched Ariston Problems
If you are seeing a lockout, loss of hot water, or your Ariston boiler keeps resetting, tell us the fault code and model and we will confirm the safest next step.
501 – ignition failure
501 is the most common Ariston fault code. The boiler tries to ignite but no flame is detected. 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.
108 – low pressure
If your Ariston shows 108, system pressure has dropped below the minimum threshold. 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.
104 – overheat protection
If your Ariston shows 104, the boiler has overheated 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 Ariston 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 Ariston Boilers Develop Faults
Ariston is an Italian manufacturer, part of the Ariston Thermo Group. Here is what we commonly see.
Ignition electrode wear
Ignition faults (501) 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 (108)
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 flow issues (103)
Code 103 can indicate poor circulation through the system. This may be caused by a failing pump, sludge buildup, or closed radiator valves. A powerflush may help restore flow.
Fan faults (607)
Fan faults prevent safe combustion and flue gas extraction. The boiler will lock out for safety. Causes include fan motor failure, wiring faults, or PCB issues.
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.
Ariston Models We Repair
We repair Ariston combi, system, and regular boilers in London, including:
E-Combi range: E-Combi 24, E-Combi 30, E-Combi 38
E-System range: E-System 15, E-System 18, E-System 24, E-System 30
Clas range: Clas HE, Clas ONE, Clas System
Genus range: Genus HE, Genus Premium
Other models: Microgenus, Microsystem, and older Ariston units
Ariston parts are available through the Ariston Group network. We check availability before attending and advise honestly if repair is not viable or cost effective.
Repair or Replace Your Ariston 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.
Ariston Boiler Servicing
Annual servicing reduces breakdown risk and keeps your Ariston 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).
Ariston Repairs Across London
London wide coverage for Ariston 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 • Main • Vokera • Alpha
View all brands
Ariston Boiler Repair FAQs
How quickly can you attend for an Ariston 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 Ariston parts?
We stock common Ariston parts including diverter valves, ignition electrodes, pressure sensors, fans, and PCBs. Parts are available through the Ariston Group network.
Is it safe to reset my Ariston boiler?
Try one reset. If the fault returns after resetting, stop and call an engineer. Do not keep resetting, especially for 104 overheat faults.
How much does an Ariston 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
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