Domestic hot water control

Some Google Nest thermostats can control hot water in addition to heating your home. Depending on your thermostat model, it may work with a simple On/Off hot water tank, an OpenTherm hot water tank, or an OpenTherm combi boiler.

Before you start

Make sure your Nest thermostat works with your domestic hot water system. Refer to the table below.

How to tell which Nest thermostat you have

	Nest Thermostat E	3rd gen Nest Learning Thermostat1
Separate hot water tank with On/Off control	-
OpenTherm2 combi boiler (hot water temperature)
Proprietary systems	-	-
Electric hot water tanks	-	-

¹ Only the models listed in the table above can control hot water. The 2nd gen Nest Learning Thermostat doesn't control domestic hot water.

² Check for the OpenTherm logo on your boiler or contact your system’s manufacturer and ask about your model. To save more energy, learn more about how the Nest thermostat works with OpenTherm.

Separate hot water tanks (On/Off or OpenTherm)

If your system has a separate On/Off or OpenTherm hot water tank, your Nest thermostat can control it if it's compatible. Check the table above for compatibility.

Tip: If you have a combi boiler, these features aren't available because hot water is produced on demand.

Set up a hot water schedule

By default, your Nest thermostat heats water from 6:00 AM to 8:00 AM and from 4:00 PM to 10:00 PM.

You can always change your hot water schedule with the Nest app, Google Home app, or the thermostat itself. You can set the time and duration for heating water and set a different schedule for every day of the week.

With the Nest app

1. Open the Nest app .
2. Select Hot Water Schedule . This leads to a dedicated schedule for your hot water settings.
   • To edit an existing schedule, tap a day to view its scheduled events. Tap again to edit the day, its start and end time, and the days the schedule repeats on.
   • Tap Add to create a new schedule.
   • Tap Remove to delete a schedule.

With the Google Home app

1. Open the Google Home app .
2. Tap Home   Climate   your thermostat.
3. Tap Settings Hot water Schedule.
4. Select the day which you want to add or edit a schedule on.
   • Add a schedule: Tap Add, set the start and end time of your schedule, then select the days it will repeat on.
   • Edit a schedule: Tap Edit, set the start and end time of your schedule, then select the days it will repeat on.
5. Tap Save.

On your thermostat

1. Press your thermostat's ring and select Settings Hot Water Schedule.
2. Choose to Enable, Disable or Edit your domestic hot water schedule.
3. To scroll through the days of the week, turn the thermostat ring. To add a new heating schedule, press the ring while an empty time is selected. To edit or delete it, press the ring when an existing schedule is selected.

Automatically stop heating water when nobody's home

Your thermostat will stop heating water when it detects that your home is empty for at least 48 hours. While your system is turned off, it won't follow your hot water schedule. Heating resumes when someone returns home.

With the Nest app

1. Open the Nest app .
2. Tap Hot Water Settings Home/Away Assist.
3. Turn Home/Away Assist on or off.

With the Google Home app

1. Open the Google Home app .
2. Tap Home   Climate   your thermostat.
3. Tap Settings Hot water.
4. Make sure that Eco when away is on.

On your thermostat

1. Press your thermostat's ring and select Settings Home/Away Assist Hot water.
2. Choose Enable or Disable.

Tip: If you have a Nest Learning thermostat (3rd gen) and Bacteria Prevention is enabled, your thermostat can still periodically heat the water in your tank.

How the Nest thermostat helps prevent Legionella bacteria

Get hot water on demand (Boost)

If you need hot water for longer or at a different time than what’s scheduled, you can use Boost to heat the water for a specified duration. After that, your hot water tank goes back to its regular schedule.

With the Nest app

1. Open the Nest app .
2. Select Hot Water.
3. Tap ON.
4. Tap Start.

With the Google Home app

1. Open the Google Home app .
2. Tap Home   Climate   your thermostat.
3. Tap Hot water.
4. Choose between 30 min, 1 hr, or 2 hr for how long you want to boost hot water.
5. Tap Start boost.

After you start the boost, the hot water state (both the manual boost and the hot water) are now visible on the Hot Water tile.

On your thermostat

Important: The menu should say "Stop Boost" if hot water is already being boosted.

1. Press your thermostat's ring and select Hot Water .
2. To select how long you want to boost hot water, turn the ring, then press your thermostat ring to start.

Manually turn water heating on or off

If you’ll be away for an extended period, you can manually turn off heating for your hot water tank. When you want to go back to your existing hot water schedule, you need to turn heating back on again.

With the Nest app

1. Open the Nest app .
2. Select Hot Water Settings .
3. To switch your hot water on or off, tap the On/Off slider.

With the Google Home app

1. Open the Google Home app .
2. Tap Home   Climate   your thermostat.
3. Tap Hot water Schedule.
4. Turn off Use schedule.

On your thermostat

1. Press your thermostat's ring and select Settings Hot Water Schedule.
2. To turn your schedule on or off, choose Enable or Disable.

Tip: If you have a Nest Learning thermostat (3rd gen) and Bacteria Prevention is enabled, your thermostat can still periodically heat the water in your tank.

How the Nest thermostat helps prevent Legionella bacteria

Set hot temperature (OpenTherm only)

If you have an OpenTherm hot water tank, you can control the temperature of the water.

Important: In many cases, your Nest thermostat should be able to control water temperature with OpenTherm boilers. However, because OpenTherm standards can vary, your boiler might not be able to do this.

With the Nest app

1. Open the Nest app .
2. Select Hot Water Settings Set Temperature.
3. To set the water temperature, adjust the slider.

With the Google Home app

1. Open the Google Home app .
2. Tap Home   Climate   your thermostat.
3. Tap Hot Water.
4. Adjust the slider to set the temperature of your hot water.

On your thermostat

Important: The minimum 55ºC (131ºF) temperature setting for hot water tanks is to help reduce the chance of Legionella bacteria contamination.

1. Press your thermostat's ring and select Settings Hot Water Schedule Equipment.
2. Continue to the next screen and choose Hot Water Temp.
3. Select your desired water temperature.

OpenTherm combi boilers

If you have a system that uses an OpenTherm combi boiler, your Nest thermostat can control it if it's compatible. Check the table above for compatibility.

Tip: You don’t need to create a schedule or control when hot water turns on because combi boilers produce hot water on demand.

Set hot water temperature

In many cases, your Nest thermostat should be able to control water temperature with a combi boiler that’s OpenTherm compliant. So, you can turn up the water temperature in the winter a bit for a warmer bath or shower, and turn it down in the summer for better comfort in hot weather and to help save energy.

However, because OpenTherm standards can vary, your boiler might not be able to do this. If this is the case, you should be able to set the water temperature manually on your combi boiler.

To find instructions for setting hot water temperature, select your thermostat below.

Nest Thermostat E

Use your thermostat to set the hot water temperature.

1. Press your thermostat's ring and select Settings Equipment.
2. Your current equipment and settings should appear. Select Continue.
3. Select Hot water temp and then adjust the hot water temperature to your preference.

3rd gen Nest Learning Thermostat

With the Nest app

1. Open the Nest app .
2. Select Hot Water Settings Set Temperature.
3. To set the domestic hot water temperature, tap and drag the slider.

On your thermostat

1. Press your thermostat's ring and select Settings Hot Water Schedule Equipment.
2. Continue to the next screen and choose Hot Water Temp.
3. Select your desired domestic hot water temperature.

Tip: The minimum temperature setting for combi boilers with OpenTherm control (40ºC) is lower than hot water tanks (55ºC). Combi boilers don't store hot water in a tank and the risk of the formation of Legionella bacteria is very low.

Troubleshoot hot water control

If there aren’t any options

Check your thermostat model

Domestic hot water control isn't available for the 2nd gen Nest Learning Thermostat. In addition, not all Nest thermostats support all types of hot water systems. Check the table at the top of this article. If you’re not sure which thermostat you have, learn how to check which Nest thermostat you have.

Check the installation

If your thermostat is compatible with your hot water system but there’s no hot water controls in the app or on the thermostat, you or your installer may have set up your thermostat to control heating only. If that’s the case, then hot water is controlled by your system programmer rather than your thermostat.

Contact a Pro installer

To help you configure your thermostat and correctly control your domestic hot water, you can contact a Professional in your area.

If there are some options for hot water

Some of the options listed above don’t appear for certain types of hot water systems.

Simple hot water tank with On/Off controls

There's no option to control water temperature. That’s because this type of system doesn't support water temperature control through the Nest thermostat.

Combi boiler

Your combi boiler produces hot water on demand. So, there are no options to create a schedule, automatically switch temperature, or Boost your hot water.