Learn about domestic hot water control and how to change settings

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.

First, check compatibility: make sure your Nest thermostat works with your domestic hot water system. For help identifying your thermostat model, see our article about how to tell which Nest thermostat you have.

 

Nest Thermostat E

3rd gen Nest Learning Thermostat1

Separate hot water tank with On/Off control

-

Separate OpenTherm2 hot water tank

-

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 does not control domestic hot water.

2 Look for the OpenTherm logo   on your boiler, or contact your system’s manufacturer and ask about your model. If you’d like to learn more about how the Nest thermostat works with OpenTherm to save you more energy while keeping you comfortable, see our OpenTherm article.Opentherm logo

Separate hot water tanks (On/Off or OpenTherm)

If your system has a separate On/Off or OpenTherm hot water tank and your Nest thermostat is compatible (see the table above), then your thermostat can control when your system heats the water in your tank.

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

Set up a hot water schedule

By default, your Nest thermostat will heat water from 6am-8am (06:00-08:00) and from 4pm-10pm (16:00-22:00).

Of course, you can always change your hot water schedule with the Nest app, just like you can change your heating schedule. You can set the time and duration for heating water as well as set a different schedule for every day of the week.

With the Nest app

  1. On the Nest app home screen, select Hot Water Hot water icon (droplet).
  2. Select Schedule Nest app schedule icon.
  3. Select a day that you’d like to edit. You can add a new scheduled heating time or select one that already exists and edit or delete it.

On your thermostat

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

Use Home/Away Assist to stop heating water when nobody's home

With Home/Away Assist, your thermostat can stop heating the water in your tank after it detects that your home has been empty for at least 48 hours. While your system is turned off, it won’t follow your hot water schedule until Home/Away Assist detects that someone has come home again.

With the Nest app

  1. On the Nest app home screen, select Hot Water Hot water icon (droplet) and then Settings Nest settings icon and then Home/Away Assist.
  2. Tap the slider to turn Home/Away Assist on or off.

On your thermostat

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

Note: If you have a 3rd gen Nest Learning thermostat and you have Bacteria Prevention turned on, your thermostat may still periodically heat the water in your tank. For more information, see our article about how Nest thermostats can help 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 will go back to its regular schedule.

With the Nest app

  1. On the Nest app home screen, select Hot Water Hot water icon (droplet).
  2. Tap the large Boost button.
  3. Choose how long you want to boost hot water.

On your thermostat

  1. Press your thermostat's ring and select Hot Water Hot water icon (droplet).
  2. Turn the ring to select how long you want to boost hot water, then press your thermostat ring to start.

Note: The menu will say Stop Boost if hot water is already being boosted.

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’ll need to turn heating back on again.

With the Nest app

  1. On the Nest app home screen, select Hot Water Hot water icon (droplet) and then Settings Nest settings icon.
  2. Tap the slider to switch your hot water on or off.

On your thermostat

  1. Press your thermostat's ring and select Settings Nest settings icon and then Hot Water Schedule.
  2. Choose to Enable to turn your schedule on, or choose Disable to turn your schedule off.

Note: If you have a 3rd gen Nest Learning thermostat and you have Bacteria Prevention turned on, your thermostat may still periodically heat the water in your tank. For more information, see our article about how Nest thermostats can help prevent Legionella bacteria

Set hot temperature (OpenTherm only)

If you have an OpenTherm hot water tank, you may be able to control the temperature of the water.

Note: 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. On the Nest app home screen, select Hot Water Hot water icon (droplet) and then Settings Nest settings icon and then Set Temperature.
  2. Tap and drag the slider to set the water temperature.

On your thermostat

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

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

OpenTherm combi boilers

If you have a system that uses an OpenTherm combi boiler and your Nest thermostat is compatible (see the table above), then your thermostat may be able to control hot water temperature.

Tip: You won’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.

Select your thermostat below to see instructions for setting hot water temperature.

Nest Thermostat E

Use your thermostat to set the hot water temperature.

  1. Press your thermostat's ring and select Settings Nest settings icon and then Equipment.
  2. You'll see your current equipment and settings. Select Continue.
  3. Select Hot water temp and then adjust the hot water temperature to your liking.

3rd gen Nest Learning Thermostat

With the Nest app

  1. On the Nest app home screen, select Hot Water Hot water icon (droplet) and then Settings Nest settings icon and then Set Temperature.
  2. Tap and drag the slider to set the domestic hot water temperature.

On your thermostat

  1. Press your thermostat's ring and select Settings Nest settings icon and then Hot Water Schedule and then 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) because combi boilers do not store hot water in a tank and the risk of Legionella bacteria forming is very low.

Troubleshooting 

If you don't see any options

Check your thermostat model: Domestic hot water control is not 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, see our instructions about how to check which Nest thermostat you have.

Check the installation: If your thermostat is compatible with your hot water system but you don’t see 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 Nest Pro: You can always contact a Nest Pro to help you configure your thermostat to correctly control your domestic hot water. 

If you see some options for hot water

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

Simple hot water tank with On/Off controls: You won’t see an option to control water temperature. That’s because this type of system does not support water temperature control through the Nest thermostat.

Combi boiler: Your combi boiler produces hot water on demand. So you won't see options to create a schedule, enable or disable Home/Away Assist switching, or Boost your hot water.

Was this helpful?
How can we improve it?