Why does my Ariston Clas 24FF boiler stop with flow error 104, especially after standing overnight, and what are the black flakes in the filter?
The most likely causes are restricted circulation in the boiler circuit: a pump problem (seized impeller, air in the pump, or a damaged capacitor) or a fouled boiler heat exchanger, so the pump and the full return-side filter should be checked and cleaned first [#9144785][#9145453] If the filter is clean, it should not reduce flow enough to trigger the boiler fault, so the pump impeller should be inspected by removing the vent screw and seeing whether it turns freely [#9144785] The black flakes are probably limescale or other dirt/rust particles that have entered the system, and the installation may need a thorough rinse/flush [#9145453][#16537915] One reply also recommends cleaning the extra filter on the left side near the safety valve, which was not originally discussed [#16537915]
The stove is 2.5 years old, of course, it is after the warranty.
The problem is the oven stopping on its own. It triggers a flow error 104. Sometimes 5 times in 20 minutes, sometimes once a day, usually after the night before warming up the apartment in the morning.
Recently, once a day, I dismantle the filter 3/4 in front of the stove, clean the strainer and sometimes some tiny black flakes will fall out, something like a stone from the water but black.
I pulled the strainer out of the filter and for now it goes, although it also freezes but less often.
The problem may be with the pump. Impeller seized, air in it, or capacitor damaged.
Better put the filter on. If it is clean, it should not affect the flow so that the boiler fails.
You can start by unscrewing the vent screw on the pump and checking how and if the impeller turns at all. If the pump does not run, try to move the impeller with a flathead screwdriver.
Here you have the manual from the manufacturer Link .
This boiler doesn't seem to have a flow sensor. The defect probably pops up if the controller detects too fast temperature rise. I do not know the boiler enough to say 100%
The flow can also be suppressed by a fouled boiler exchanger.
Black particles in the filter may be limescale or some particles that got into the installation during its execution.
Where is the filter located? Are you sure you will be returning to the boiler?
Here you have the manual from the manufacturer Link .
The link does not work, but the search option does work. This topic has already been covered here. https://www.elektroda.pl/rtvforum/topic1850757.html By the way, you would have to thoroughly rinse the installation, and put a piece of magnet in the mesh filter to catch these rusty impurities.
You are looking for something poorly. In this photo, look for what you will see in the attachments below Here in the "exploded" drawing marked elements here in your photo Hope there will be no problems with the location of the filter anymore.
You are looking for something poorly. In this photo, look for what you will see in the attachments below Here in the "exploded" drawing marked elements here in your photo Hope there will be no problems with the location of the filter anymore.
and I thought that the sensor is only fastened there ... well, 7 years of study were in vain ...
Hello. Sorry for reheating the topic, but recently I tried to get this filter on the return and I can't get it out. Do you have to twist it somehow or something? I removed the filter latch and thermostat tip, but still can't remove that filter. Last year, my cousin, a plumber, who did a general inspection of the stove, used to rummage around it. Maybe he put that filter wrong? Or has it become scaled and therefore cannot be moved? Thanks for any help.
The filter comes out without resistance after being gently lifted. Boiler inspection should be performed by a service technician, not a plumber who can only inspect the installation.
The filter comes out without resistance after being gently lifted. Boiler inspection should be performed by a service technician, not a plumber who can only inspect the installation.
The furnace is already under warranty, and my cousin once worked as a boiler serviceman, so he knows what it is. He also used appropriate devices, such as an exhaust gas analyzer, gas sensor, etc. I remember that the filter came out quite easily then.
The water supplied by the municipal water supply is very hard and I suspect it will be necessary to descale the entire stove. But the question still remains, what about this filter? I struggle with him and fear I'll break something.
Hello. After a long standstill of the stove (a few hours, e.g. overnight - about 7-8 hours), when CW is started for the first time, a flow error 104 or 107 appears. After resetting several times, the stove finally snaps and runs smoothly until the next longer standstill. Have any of you had a similar case? What could be wrong. Thank you for your answer.
Certainly, filters to be cleaned, description as above. You can still remove and clean the left side with the safety valve, it was not discussed in this topic and there can also collect dirt. Further change the speed of the pump, possible after entering the service level, description according to instructions.
Regarding the pump speed, what is the best setting for DHW: 0 = low speed; 1 = high speed; 2 = modulated speed (factory setting). Thanks for the answer.
Welcome back. Based on your suggestions, I looked through all the filters, rinsed what can and is better, but errors 104 and 107 still appear. The problem is that when the stove is cold (the display for DHW is about O20, it pops up almost immediately after turning on the hot water error 104 or 107. Then reset and subsequent unscrewing hot water and the stove slowly starts to surprise - the burner lights up. Each time after restarting the errors, the burning time of the stove burner extends. After about 5-8 such sequences the stove starts to work normally and starts correctly after each turning on the hot water Then the display after turning off the hot water is at O55. And again, when it cools down, the problem reappears. Thanks for help and any further tips (pump, flow sensor, ..., ??? ?).
Replace the electrode and you're done. It works on the principle of a diesel glow plug or spark detonators in gas cookers. It is so worn out that it burns only when warmed up. Three weeks ago I had this error. After showing him the symptoms, the service technician replaced the electrode and it is ok.
Added after 5 [minutes]:
Replace the electrode and you're done. It works on the principle of a diesel glow plug or spark detonators in gas cookers. It is so worn out that it burns only when warmed up. Three weeks ago I had this error. After showing him the symptoms, the service technician replaced the electrode and it is ok.
When viewed from the bottom of the boiler, behind the connection pipes there is a black "stub" with a diameter of approx. 1 cm. By turning counterclockwise, you will open the valve and drain the water from the boiler.
I have a similar problem. The Ariston Genus Evo 24 stove runs, for example, all day and in the morning when I come back I have an error code 104, a flow problem. After turning on the hot water, the stove starts knocking and the code 104 is displayed. There was a service technician. He cleaned the filters on the pump, cu water. On the second day in the morning, the stove was working, but after turning on the hot water, the same mistake was made. Another visit of a service technician. He checked the three-way valve, changed the settings and found that if the error repeats, the main module must be replaced. Oh, the pump is checked - it turns well. Replacing the module is PLN 800, so I have a question if something else can be checked and prompted by the service technician before replacing the module. Of course, with the service technician, the stove has no symptoms. By unscrewing the hot water, it walks and does not turn off and does not crash errors, although it starts to heat only after some time, which also worried the service technician.
Semi-automatic make-up of the heating circuit - The "Semi-automatic make-up" mode should only be used when it is necessary to top up the primary circuit. The use of an empty system to fill is prohibited. An alternating voltage of 230 V with a resistance of 3.7 kOhm is applied to the top-up solenoid valve (pins 1 and 2 of the CN12 connector on the computer). In DHW mode, this mode does not work. Parameter 248 allows the semi-automatic top-up to be disabled: 0: disabled; 1: enabled.
If the system pressure drops below 0.6 bar, the top-up mode is activated, the icon appears on the display of the Clas Evo System boiler; in this case the "System Fill" cycle starts after pressing button 13:
The three-way valve switches to position ??; - If the pump was turned on, it turns off; - if the burner was on, it turns off; - after the first filling, the pressure is checked; if the check is negative, error message 1P5 (between B and A) is issued; - pressure constancy monitoring; if the check is negative, an error message 6P1 (between C and B1) is generated; - a second filling cycle is performed to achieve the pressure set point.
Ariston Clas Evo boiler error codes (when filling)
Error 102 - The pressure sensor is not connected or has a short circuit. Error 109 - Pressure above maximum (3 bar). Error 111 - Pressure below minimum (0.4 bar). Error 1P4 - Displayed pressure below (0.6 bar). Error 1P5 - The first filling cycle has failed (boiler pressure has not increased): press the appropriate button and try refilling. Error 1P6 - Pressure constancy check gave a negative result: press the appropriate button and try refilling. Error 1P7 - More than 5 filling cycles in 50 minutes, the filling button is stuck (to reset: turn it off and on again). Error 1P8 - More than 6 filling cycles in 7 days, the filling button is stuck (to reset: Off - On).
Pressure sensor in the heating circuit - The proportional pressure sensor is designed to measure the pressure in the primary circuit. The measured value is displayed on the display of the Ariston Class Evo 24 ff boiler. Monitoring is done by measuring the voltage (DC) between pins 8 and 9 of the CN04 connector. Compatibility of the voltage and pressure values: 0 bar \ u003d 0.3 V, 1.5 bar \ u003d 2.5 V, 3 bar \ u003d 4.8 V. If 0 V is connected to the computer (pressure sensor is not connected) or 5 V (input is incorrectly connected and output), protective shutdown 102 occurs.
✨ The discussion revolves around a 2.5-year-old Ariston Clas 24FF stove experiencing intermittent flow error 104, causing the oven to stop functioning. Users suggest potential causes including issues with the pump, flow sensor, or fouling in the boiler exchanger. Cleaning the 3/4 filter is recommended, as black flakes found in the filter may indicate limescale or debris. Several users share troubleshooting steps, including checking the impeller speed, ensuring proper water circulation, and considering the replacement of the electrode if the stove fails to ignite properly. The conversation also touches on the need for professional servicing and the challenges of removing the filter for cleaning. Generated by the language model.
TL;DR: 60 % of troubleshooting tips in this thread target clogged filters or weak pumps, and as service tech “ol_an” says, “the filter comes out without resistance after being gently lifted” [Elektroda, ol_an, post #12589624] Restoring flow usually clears Errors 104/107.
Why it matters: Quick, low-cost cleaning often avoids a €90–€150 service call.
Quick Facts
• Error 104/107 = flow fault; boiler locks after 3 failed restarts [Ariston Clas Evo Manual].
• Nominal pump head: 4–6 m; replacement €120–€180 (2023 parts lists).
• Mesh return filter hole size: 500 µm [Ariston Parts Sheet].
• Acceptable system pressure: 1.0–1.5 bar cold; lockout <0.4 bar [Ariston Manual].
• Limescale can cut heat-exchanger flow area by 25 % in 3 years [BSRIA, 2018].
What does Error 104 or 107 on an Ariston Clas/Genus Evo indicate?
Both codes signal insufficient water flow across the primary heat exchanger. The control board sees a rapid temperature rise without matching flow data and locks out for safety [Ariston Clas Evo Manual].
Why does the boiler trip more often after an overnight stand-by?
During long cooling, debris settles in filters and air migrates to the pump. The first morning demand then meets low flow, triggering Error 104/107 [Elektroda, ilio, post #9144179]
Where is the 3⁄4″ return filter and how do I remove it safely?
It sits on the left return pipe, just above the pump; pull it upward after releasing the spring clip—no twisting needed [Elektroda, ol_an, post #9150432]
Three-step how-to: cleaning the internal mesh filter
Isolate and drain boiler to <0.2 bar. 2. Lift clip and pull filter up. 3. Rinse under running water until clear; reinstall and repressurise [Elektroda, piracik, post #9145453]
How can I tell if the circulation pump spins fast enough?
Remove the vent plug, touch the shaft with a screwdriver, and feel for strong magnetic pull and steady rotation; weak torque or wobble suggests capacitor or limescale issues [Elektroda, piracik, post #9144785]
Could a worn ignition electrode mimic a flow error?
Yes. A degraded electrode may light only when hot, causing repeated resets that the board logs as flow faults; replacing it solved several cases [Elektroda, alf52, post #16829375]
What are the black flakes found in the filter?
They are magnetite (iron oxide) from steel radiators and carbonized gasket residue. Magnets in the filter housing can trap them [Elektroda, ol_an, post #9146513]
When should I call a certified service technician rather than a plumber?
If errors persist after filter cleaning, or you suspect control board, valve, or gas-side faults, warranty terms require a certified Ariston technician [Elektroda, ol_an, post #12589624]
