Account
A warm towel rail on winter mornings

A warm towel rail on winter mornings

How it works

The Shelly 1PM Gen4 sits in the towel rail's supply and switches it on and off. A schedule stored on the relay does the rest: it switches the rail on at the time you choose, on the days you choose, and the Toggle value after setting switches it off again once the seconds you entered have passed.

The 1PM also measures power. The app shows what the rail is drawing right now and a chart of the last 24 hours, so you can see when it heated and whether it was left on.

  1. Shelly app schedule screen for a device named Towel rail, with Monday to Friday ticked under Choose Weekday. 01

    Your phone

    Set the weekday and weekend times once.

  2. 1PM Gen4 Smart Relay 02

    Shelly relay

    Switches the rail on in the morning and off before you leave.

  3. 03

    Your towel rail

    Warm when you step out of the shower, off for the rest of the day.

What it looks like on your phone

  • Weekdays. Tick Monday to Friday and leave the weekend alone.

  • The action. On, then toggle back after 5400 seconds, which is 90 minutes.

  • Saved. One schedule switches the rail on at 06:00 and off again 90 minutes later.

Step by step

How you'll set it up

Add the device to Wi-Fi from your phone, or straight from a browser.

Download Shelly Smart Control on the App Store Get Shelly Smart Control on Google Play

  1. Fit the Shelly to the rail's supply

    Mains goes to L and N. The rail connects to O and neutral, and its wall switch, if it has one, goes to SW so it still works as before.

    Wire map 1PM Gen4
    • Active (supply) L
    • Neutral N
    • Appliance O
    • Wall switch (optional) SW
    Circuit overview
    LN230 V~ 50 Hz1Appliance2Wall switchOSWLLLNNShelly 1PM Gen4
    1Appliance2Wall switch
    Active (supply)Neutral / 0 VSwitched loadSwitch signal / dry contact

    In Australia, fixed 230 V wiring is licensed-electrician work. Use these diagrams to plan the job and brief your electrician.

    Showing the whole circuit

    Shelly 1PM Gen4

    100%
    LN230 V~ 50 Hz1Appliance2Wall switchOSWLLLNNShelly 1PM Gen4
    1Appliance2Wall switch

    Select a terminal to follow its wiring.

  2. Add it to the Shelly app and name the output

    Add the relay in the Shelly app, then name the output Towel rail. Switch it on with the power button and the main screen shows what the rail is drawing, in watts. In the web interface, open the output, enter Towel rail under Name and click Save.

    Learn how to add a device to the Shelly app

  3. Add a weekday schedule

    Open the Schedule tab and tap Add schedule. With Simple selected, tick Monday to Friday under Choose Weekday, then tap Next. Choose Time, set the time you want the rail heating (an hour before you get up is a good start) and tap Next. In the web interface, open Schedules and click Create schedule, enter the Time and select Monday to Friday.

  4. Switch it on, then off again

    Tap Add local action and choose Control Output. Set it to On, tick Toggle value after and enter 5400, which is 90 minutes in seconds. Tap Save, then Next, then Save. The rail comes on at your time and switches itself off 90 minutes later. In the web interface, click Add action to execute, choose Control Output, set it to On and Flip value after to 5400, then click Save local action and Save.

  5. Add a weekend schedule if you want one

    Repeat the last two steps with Saturday and Sunday and a later time, so the rail is warm when you are up rather than when the alarm goes.

  6. Check the schedule

    Schedule now lists Monday to Friday: On at 06:00 and back off after 5400 seconds, with the weekend line below it if you added one. Schedules in the web interface shows the same list.

  7. Add it to your home app over Matter

    Matter is on by default on the Gen4, so scan the QR code on the device label with Apple Home, Google Home or SmartThings.

Optional: only when the room is cold

The weekday schedule switches the rail on whether or not the bathroom needs it. A Shelly BLU H&T on the bathroom wall measures the room, so the rail can come on only when the temperature drops below a level you choose, and switch off again once it's warm. The relay is a Bluetooth gateway for Shelly BLU sensors, so you don't need a separate hub.

  1. Put the sensor in pairing mode

    Press the button on the sensor four times quickly. Its light flashes once every two seconds for a minute while it waits to pair. Five presses starts Zigbee pairing instead, which isn't what you want here.

  2. Add it in the Shelly app

    Add the sensor in the Shelly app, in the same room as the rail, and choose the relay as its Bluetooth gateway. The relay passes the sensor's readings on, so there is no hub to buy.

  3. Fit it in the bathroom

    Fix the sensor to a wall away from the towel rail, so it reads the room rather than the rail's own heat.

  4. Switch the rail on when it's cold

    In the Shelly app, open the room's Scenes and add a scene. For When, choose Device based, then the sensor's Temperature, and set it to drop below 20 °C. For Do, choose Device action, Towel rail and turn on. Name it Rail on when cold.

  5. Switch it off when it's warm

    Add a second scene with the sensor's Temperature rising above 22 °C, and Towel rail turn off as the action. The rail now follows the room, and the weekday schedule still gives it a set morning run. Delete the schedule if you want the temperature alone to decide.

Frequently asked questions

Should I use the Shelly app or Home Assistant?

If you don't run Home Assistant, use the Shelly app: it needs no hub, and the schedule is stored on the relay, so it runs even when your phone and the internet are off. If Home Assistant already runs your home, put the rail there, so it can sit alongside your other automations.

Will the rail's own switch still work?

Yes. The switch connects to the relay's SW input, so it still turns the rail on and off. Only the scheduled run switches itself off; if you turn the rail on by hand, turn it off again when you're done.

Will it work with my towel rail?

Check the rating on the rail's label against the relay: the 1PM Gen4 switches up to 16 A and the 1PM Mini Gen4 up to 8 A. The relay wires into the supply, so it suits a hardwired rail. A rail that plugs into a wall socket needs a plug-in smart plug rated for its load instead.

How long should the rail run for?

Start with 90 minutes and adjust to suit your rail and your morning. Home Assistant's History for the rail's Power sensor shows when it was drawing, which makes it easy to see how long it actually needs.

What if I'm running late or up early?

Switch it on from the Shelly app, your home app or the wall switch. The schedule keeps running on its usual days.

Can the rail come on only when the bathroom is cold?

Yes, with a Shelly BLU H&T on the bathroom wall. The relay can't measure room temperature itself, but it is a Bluetooth gateway for Shelly BLU sensors, so a scene can switch the rail on below a temperature and off above another.

What happens if the internet drops out?

The relay works on your local Wi-Fi and the schedule is stored on the relay itself, so it doesn't rely on Shelly's cloud to run. Control from outside the house does.

Can I see how much power it uses?

Yes. The 1PM measures the rail's power draw, shown live in watts on the main screen with a chart of the last 24 hours, so you can see how much the rail is heating and spot a rail that has been left on.

Does it still run if Home Assistant is off?

No. The automation runs in Home Assistant, so the rail won't come on while Home Assistant is down. The wall switch still works. If you'd rather the timer kept running on its own, set the schedule in the Shelly app instead: it's stored on the relay.

Still need a hand?

We answer most messages within one business day. If your question is about an existing order, have your order number ready. It speeds things up.

Contact us