Ariston CLAS ONE 24 heating schedules: what to check

If your heating starts at the wrong time, stays in a constant mode or ignores a change you made in an app, the boiler may not be the device that holds the schedule.

On an Ariston CLAS ONE 24, the heating times can depend on the controls fitted with the boiler. Some homes use an Ariston room control, some use the Ariston Net app, and others have a separate thermostat or programmer. The first useful step is to identify the control before changing settings or resetting the boiler.

This guide applies to the UK Ariston CLAS ONE 24 combi, product code 3301043 and G.C.N. 47-116-85. Control layouts and menus differ on other CLAS models and on third-party thermostats.

Start by finding the schedule owner

The CLAS ONE boiler front panel controls the boiler's operating mode and heating-water temperature. A connected room controller or app may hold the daily heating times.

Use this quick check:

1. Confirm the boiler model from your paperwork. Look for CLAS ONE 24, product code 3301043 or G.C.N. 47-116-85 in the handover documents. Do not remove the boiler casing to look for a label.
2. Identify the room control. Note the make and model shown on the thermostat or programmer. If it says CUBE S NET, use the CUBE S NET guidance below. Do not apply those symbols or menus to a different control.
3. Check whether an app is involved. If your household uses Ariston Net, the schedule may be managed there. Make sure you are looking at the correct home and heating zone.
4. Keep a short record. Photograph the controller screen, boiler display and any fault code. Do not include account details or Wi-Fi passwords.

Ariston's current UK product information says the CLAS ONE is compatible with Ariston controls and Ariston Net. That does not mean every CLAS ONE 24 has a connected control fitted.

What the CUBE S NET symbols mean

Only use this section if the installed control is labelled CUBE S NET.

The official CUBE S NET manual identifies separate display states for:

• Programmed — the control is following a time programme.
• Manual — a steady manual setting is active instead of the programme.
• Override — a temporary change is active.
• Holiday — holiday mode is active.
• Wi-Fi — the controller's connection state is shown on the display.

If the house is warm at unexpected times, first note which of these states is showing. A manual, override or holiday state can explain why the normal programme is not behaving as expected.

The CUBE S NET manual also says that, when it is paired with a boiler that does not have its own internal clock, an internet connection is needed to show the current time and configure time scheduling through the Ariston Net app. The exact effect of losing Wi-Fi therefore depends on the equipment in your home.

Ariston's current UK CUBE S NET page lists 16 August 2026 as the end of its software-support period. That date does not prove that an installed thermostat has stopped working. It does mean homeowners considering a new app-based setup should confirm the currently supported Ariston control and app route before buying equipment.

Safe checks when the schedule seems wrong

These checks do not require the boiler casing to be opened:

1. Check the boiler is in a heating mode. The CLAS ONE manual describes Winter as heating plus hot water. Summer keeps hot water available but switches heating off. If the heating symbol is absent, record the display before changing anything.
2. Check the controller state. On a CUBE S NET, look for Programmed, Manual, Override or Holiday. On another control, use that exact model's homeowner instructions.
3. Compare the time and day. A controller with the wrong clock can run the right schedule at the wrong time. If an app is used, confirm the correct home and zone before editing.
4. Compare room temperature and setpoint. If the sensed room temperature is already at or above the set temperature, the control may not be asking the boiler for heat.
5. Check the connection state. If an Ariston Net schedule is used, note any Wi-Fi or cloud-connection warning. The CUBE S NET manual says its network setup must be repeated after changes to the home network, such as a new router or password.
6. Look at the boiler display. Record any error code, pressure warning or unusual symbol. A scheduling problem is not a reason to keep pressing reset.

Do not use a button sequence from a different Ariston control or from a video for another boiler revision. If the exact controller cannot be identified, stop and ask for help rather than guessing.

When the schedule is not the real problem

A correct programme cannot make the boiler run if the heating system has another fault. Ask for professional help if:

• a fault code remains or returns;
• the boiler repeatedly locks out;
• the pressure keeps falling;
• there is water leaking from the boiler or heating system;
• the controller is calling for heat but the boiler does not respond; or
• the controller, app and boiler display give conflicting information.

Do not remove the casing, alter wiring, change installer or service-menu settings, bypass a safety device or repeatedly reset a persistent fault.

If you smell gas or suspect a gas leak, call the National Gas Emergency Service immediately on 0800 111 999. If a carbon-monoxide alarm sounds or you are concerned about carbon monoxide, get everyone into fresh air and call the same emergency number. Treat these as emergencies, not as schedule or reset problems.

What to send when asking for help

The quickest handover is a short, factual one. Include:

• the boiler model and any product or G.C.N. number in your paperwork;
• the controller make and model;
• whether an app is used;
• the controller state or symbol showing;
• the time the heating was expected to start;
• the room temperature and set temperature; and
• a clear photograph of the boiler display or fault code.

MPH can then help you identify the right next step. Read more about Ariston boilers, ask about boiler repairs and fault finding or contact MPH Boilers.

Frequently asked questions

Can I set the heating schedule on the CLAS ONE 24 boiler itself?

Ariston's UK product page refers to in-built timer programming, but the installed controller still matters. The current CLAS ONE homeowner manual does not provide one universal schedule-editing sequence. Identify the exact controller and use the matching homeowner instructions.

Does the CLAS ONE 24 work with Ariston Net?

Ariston lists the CLAS ONE as compatible with Ariston controls and the Ariston Net app. Compatibility does not confirm that the required control is already fitted or that every older accessory remains supported.

Why did my schedule disappear after a router change?

The CUBE S NET manual says its network configuration must be repeated after changes to the home internet network. Follow the guided instructions for the exact controller or ask the installer for help. Never share your Wi-Fi password in a public message.

Should I reset the boiler if the heating starts at the wrong time?

No. A timing or controller-mode problem is not, by itself, a reset request. Check the boiler mode, controller state, clock and connection first. If a fault code is present, use the exact CLAS ONE manual and arrange help if it persists.