You're right, it's not typical to have a single multi-zone controller for under-tile heating, but it's definitely understandable to want consolidated control. Here's a breakdown of options and considerations

Potential Solutions (and their challenges):
Programmable Thermostats with Remote Sensors (Combined)



How it Works

You could use high-end programmable thermostats, each with its own sensor in each zone, but then install them all at a central location. You'd be effectively mimicking a multi-zone system by grouping individual thermostats. The 'multi-zone' aspect comes from you programming each individually from one location.

Pros

More common, easier to find compatible components (thermostats and sensors).

Cons

More complex setup. The thermostats might be a bit crowded at a central location. No real intercommunication between zones (can't optimize for overall energy usage).

Limitations

This works best when the underfloor heating cables have similar power requirements.

Smart Home Hub with Individual Smart Thermostats



How it Works

Use a smart home hub (like Hubitat, SmartThings, Home Assistant, etc.) paired with individual smart thermostats designed for floor heating. The hub acts as the central controller, and you can program the thermostats through the hub's interface. This allows you to control each zone individually and even create automation rules (e.g., "If kitchen temperature is below X degrees, turn on kitchen heating").

Pros

Centralized control through a smartphone app or web interface. Automation capabilities. Remote access. Often voice assistant compatibility (Alexa, Google Assistant).

Cons

More complex setup (requires the smart hub and compatible thermostats). Potential compatibility issues between hub and thermostats. Hubs can have a steep learning curve, particularly Home Assistant.

Considerations

Ensure the chosen thermostats are rated for inductive loads, as heating cables can create a significant inductive load. Look for thermostats with floor sensor inputs.

PLC (Programmable Logic Controller) based system



How it Works

This is the most customizable and robust option, but also the most complex. A PLC is a small industrial computer designed for controlling machinery and processes. You would connect temperature sensors in each zone and use the PLC to control relays that switch the heating cables on and off.

Pros

Extremely flexible and powerful. Can handle complex control logic, data logging, and remote monitoring. Can be integrated with other building systems.

Cons

Significant programming and wiring expertise required. Higher initial cost. Overkill for a simple three-zone system unless you have specific advanced control needs.

Considerations

Requires a qualified electrician or automation specialist to design and install.

Key Considerations Before Recommending a Solution



Total Load (Amperage/Wattage) of Each Zone

This is critical for selecting the right thermostat or relay. Each controller (or relay) must be rated to handle the maximum current draw of the heating cable it controls. This is your most important safety concern.

Voltage

Confirm the voltage of the heating cables (120V or 240V is common in the US).

Wiring

How are the cables currently wired? Is there already wiring run to a central location? If not, running wiring can be a major cost factor.

Client's Technical Aptitude

A smart home hub setup requires some technical comfort. A PLC solution is only for someone with experience or a professional installer.

Budget

Costs can vary significantly between these options.

Steps to Take


Get Detailed Information

Manufacturer and model of the heating cables. Wattage/amperage of each cable. Voltage. Existing wiring configuration. Budget. Client's technical skill level.2.

Research Compatible Components

Once you have the wattage/amperage, search for thermostats or relays rated to handle that load. If using a smart hub, confirm compatibility with the thermostats.3.

Consider Professional Installation

Especially for the PLC option or if any wiring changes are required, hiring a qualified electrician is essential.4.

Safety First! Always prioritize safety. Ensure all wiring is done correctly and that all components are properly rated for the load.

Recommendation

For most residential scenarios with a desire for centralized control, a

smart home hub with individual smart thermostats is likely the best balance of functionality, cost, and ease of use. However, only if the client is comfortable with the tech. If they are not tech-savvy, grouping individual programmable thermostats is a more straightforward, albeit less integrated, solution. Be certain to check the inductive load rating of the smart thermostats. This can be a problem with less expensive thermostats.Before making any recommendation, get all the information from the client. Good luck! Flag for review