Mill WiFi Max Portable Heater 1500W Review

Design and Features

• Slightly clunky app
• Clever learning features

There’s a tiny bit of assembly before the Mill WiFi Max Portable Heater 1500W can be used, with the legs needing to be screwed into place. It’s a five-minute job, if that, and only needs to be done once.

Once completed, the heater looks stylish, with its neat white metal sides. This heater doesn’t take up too much room and I installed it next to my desk in my office.

Once powered on, the heater can be controlled via the dial on the front. A push gives you on/off control, but there’s also a twist action to adjust temperatures between 5°C and 35°C in 0.5°C increments.

You can stick with this, but it makes more sense to get the Mill WiFi Max Portable Heater 1500W connected to the Mill Norway app, which gives you remote control over the heater.

The app is good, but it works it a slightly odd way that takes some time to get used to. For example, you can run the heater without adding it to a room, but this disables some of the advanced features, so using rooms makes sense.

Rooms can contain more than one device, so a large room could be stocked with a couple of heaters, all controlled together.

Rooms operate on a default schedule, which consists of three components: a Sleep temperature, a Comfort (think daytime or when you’re in the room) temperature, and an Away temperature. You can’t edit the Standard program (the default), but you can create your own settings instead, and set the times that you want each Mode to be active.

That’s fine, but it feels like a few too many steps to set what’s effectively a schedule. I’d prefer a standard schedule, such as with Tado X, being able to set specific target temperatures at set times.

It’s also possible to set any of the modes as an override, which can be done permanently, on a timer or until a specific date/time. I prefer to use the heater this way, as I only turn it on when I want heat, and then set the override to Off when I’m not using my office.

The dial on the front of the heater can be used to manually set a temperature, but adjusting this doesn’t update the room setting in the app, which is frustrating. Often, it’s easier to quickly turn the dial up to get a bit more heat, but throws the heater out of sync with the app.

The alternative is to use the settings and turn on Control Device Individually. This gives the Mill WiFi Max Portable Heater 1500W individual target temperature controls, which the heater aims for permanently. In this mode, adjustments made on the heater are reflected in the app. But, you do lose the ability to schedule the heater to come and and off at set times.

With individual control turned on, it still makes sense to have the heater in a room, as you get access to the more advanced features, which includes Predictive Heating, where the heater learns how your rooms heats up, and turns on early to reach a target temperature at a set time; the Open Window Detector, which shuts the heater off when large temperature drops are detected; and the PID controller, which adjusts the heater’s wattage on the fly, reducing power when the target temperature is reached.

Via the app, it seems as though it’s possible to turn on Matter compatibility, although enabling the option comes up with a warning that the heater will no longer be available in the Mill app, and that weekly heating schedules, statistics, predictive heating, open window detection, timers, and the child lock will be disabled.

This seems a bit off. Most Matter devices that I’ve used continue to work with full functionality in the parent app, and with fewer options in a Matter controller. All of this turned out to be a moot point, as trying to convert the Mill WiFi Max Portable Heater 1500W to a Matter device didn’t work, as the app then doesn’t list it as one of the compatible devices.

There’s no Alexa or Google Home integration, either, so easy remote control with automations is out for these devices.

For safety, both tip-over and overheat protection are built in.

Performance

• Heats well
• Adjusts power automatically

I tested the Mill WiFi Max Portable Heater 1500W in my garden office. On full power it draws 1500W, and there’s a gentle heat that flows through the convection heater, with cold air draw in underneath and hot air passed out of the grill at the top.

At this level of power, the heater should be good for room up to 15m2 and my office definitely falls into this category.

Heating speed is basically the same as with other heaters, but the PID technology is interesting, as the wattage is dialled back when the room is near temperature, so I didn’t get the spikes I get with other heaters: a slight overshoot of temperature, then a drop before the heater kicks back in. Overall, the Mill WiFi Max Portable Heater 1500W provides a slightly more comfortable heat.

There is also a difference in energy use. I heated my outdoor office on a very cold day, taking it from 1.5°C to 14°C. Between 12pm and 1pm, the heater used 1.32kWh of power (37p at the current price cap) getting the temperature up to just over 10°C; in the following hour, as the temperature got to just under 14°C, power usage dropped to 1.15kWh (32p). 

A small difference, perhaps, but used over a year, PID could add up to some decent savings over a regular electric heater.

Should you buy it?