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Get the most out of your hybrid heat pump system

If your hybrid heating system isn't working as it should, these quick fixes will help you save some time and get your home heated properly again. 

These handy tips and tricks will help to quickly troubleshoot potential problems with your boiler, heat pump and heating controls.

1 - Common Boiler Issues

Power - first things first, check to see if your boiler has got power.

If the boiler isn't receiving power:

  1. Check your consumer unit (pictured right)

If it’s getting power, check the boiler is fuelled - is your tank empty?

If you’re getting an error message you can look it up online to find out more and see what the next steps are.

You can also try turning the thermostat up. If you have one, use your immersion heater for hot water.

Consumer unit for Hybrid Heat Pump

Low Pressure - Checking for low pressure on your boiler

You'll be able to see if your boiler has lost pressure by checking the gauge on the front;

  1. When your boiler is switched off, the pressure gauge should read around 1 to 1.5 Bar – if there’s a colour gauge, check it’s in the green zone.

  2. When it’s operating (so when heat and hot water are being demanded), the pressure will increase slightly but should drop back down into the green zone.

If the pressure is too low, you can easily re-pressurise; check your manual or search your make and model online to find a 'walkthrough' guide.

If your boiler is constantly losing pressure, check for leaks in the pipework or the boiler. You may need a Gas Safe engineer to come out for things like re-sealing or re-piping; always make sure you’re being safe.

Need more support?

If you have any problems or an engineer needs a helping hand, contact Passiv Support at or call on 0333 006 2934.

2 - Heat Pump Troubleshooting

Consumer unit for Hybrid Heat Pump

Power - Check your heat pump is getting power, the same as you would with a boiler.

If your heat pump fails, there should be an alarm or alert to let you know.  Don’t panic if this happens - there are a few simple things you can check;

  1. Check the consumer unit (pictured left). 

Are there any error messages?  If you’re getting an error message you can look it up online to find out more and see what the next steps are.

If you're still unsure, contact Passiv Support.

Wilo Circulation pump showing dial set to number 3/ 2 o'clock

Low pressure - check for a low-pressure fault.

The most common low-pressure fault will show up as an E911 fault.

Here's how you can fix it:

Check the pressure of your heat pump – firstly have a look at the advice on how to check your boiler pressure (above).

Then check that the Wilo circulation pump (pictured) is set to Speed 3.

Image of magnetic filter and its components

Blocked filter - check to see if the filter is blocked as this could cause an error.

How to clean the magnetic filter;

  1. Turn off both black isolation valves, located on either side of the filter.
  2. Unscrew the magnet and pull it out from the top of the filter.
  3. Have a small container handy to catch the water in the filter. Remove the cap on the bottom and turn the valve a quarter turn - you should see the water start to trickle out.
  4. Once the water stops, turn the valve back off and replace the cap.
  5. Screw the magnet back in, turn on both black isolation valves and bleed the air from the top of the filter like you would on a radiator (see image).

Need more support?

If this doesn't work or if you want some more help, contact Passiv Support at or call on 0333 006 2934.

3 - Controls Failure

Thermostat Troubleshoot

Thermostats are battery-powered, so check for a low battery alert on your app and replace the batteries if needed.

To change the batteries, undo the two screws at the base of the wall plate so you can remove the room thermostat sensor from the wall or back plate.

Replace with two AAA batteries (making sure they’re inserted the right way around).  The thermostat sensor can then go back on the wall – make sure you tighten the screws back in securely.


Heating Control Switch

If your Heating Control Switch (HCS) locks up, you’ll see the bottom light turn red. The easiest way to unlock is to turn it off, wait 15 - 20 seconds, and turn it back on again. This should unlock your HCS.

If your Passiv hub loses power this will stop the system from working; the hub is the control device that tells the heating/hot water to turn on and off. You’ll get an alert via the app if this happens.

If your Passiv hub loses power:

  • Turn the Passiv Hub off for 30 seconds, then turn it back on

  • The system should be restored within twenty minutes

Heating control switch

Offline Hub

If the Passiv hub loses internet connectivity, your system will keep running with the schedule and temperatures already set in the system.

If your internet has gone down, check to see if other devices are connecting and if not check your router and contact your provider if this doesn’t work. If other devices are online but the hub is unreachable, check the TP-Links (if you’re connecting this way).

Don’t turn the hub off and on if you lose internet connectivity. This will cause the hub to lose your stored schedule (time + temperature etc) which stops it from demanding heat/hot water automatically.

If the hub loses connectivity you won't be able to use the app to make changes. You can still use the thermostat to increase/decrease the temperature in the home. Your hot water should continue to heat as per your schedule. Once your internet connection is up and running you should have full-feature support again.

Need more support?

If your internet appears to be working normally but your hub won’t connect, or you want some more help, contact Passiv Support at or call on 0333 006 2934.

If you're planning on doing any of the following:

  • Extension works to your home
  • Changes to your heating system
  • Selling or moving home

Please get in touch with Passiv Support and they will help you with any necessary steps you need to take in line with your contract.

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