Heating Compatibility

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One of the most important question you might have if you can integrate your heating system with Openmotics. Let's already share the answer: In most cases, the answer is yes !

However, we advise everyone to double check if your system is compatible. To do that, it's important to understand the basics. In this page, we will first explain how a heating system normally works and how it works in combination with Openmotics, then check if your system is compatible.

We will base the whole explanation on a heating system with room radiators but we will also explain the possible combinations (Radiators in combination with floor heating, floor heating with AC etc).

Interested how installation must be done? Please consult the Hardware Installation Guide.

Interested which actuators to use? Please consult the Additional Material page.

Interested how the Openmotics thermostats work? See the Thermostat page.

The thermostat system can be programmed using the graphical user interface. Interested how to program thermostats by using the CLI interface? See the CLI Thermostat Setup Pages.

How does a heating system work?

Heating traditional.jpg

In a traditional setup, you've following components:

  • Heating boiler
  • Room thermostat
  • Collector
  • Radiators with thermostatic head
  • Outside sensor (optional)

Your room thermostat (mounted in the living room) will give a signal to the heating boiler when heating is needed and the water pump will start running. The hot water will be sent to the radiators and when the thermostatic head on the radiator is opened, the water will go through the radiator and the water will be cooled and returned to the heating boiler. The Heating boiler will measure the temperature difference between the outgoing water temperature and the incoming water temperature which is called the delta T.

When the delta T is high, the boiler will start heating, when the delta T is low, the boiler will stop heating. The temperature of the outgoing water depends on the heat output curve. The heat output curve plots the water temperature that will be send to the radiators which will depend on the outside temperature. When the outside temperature is colder, the water sends to the radiators will be hotter. The curve is programmable and depend on the isolation applied.

Every radiator will have a thermostatic head that will opens and closes depending on the temperature in the that room. Typically, you can set such thermostatic head to a certain temperature. All rooms will follow the living room in other words, when the living is not heating (or has reach his setpoint), the rest of the rooms won't heat either. So opening a thermostat head in the kinder room won't have any effect. Some systems solve this problem by keeping the pump running.

What changes are needed to combine Openmotics with your heating system

Heating with Openmotics.jpg

What we do is very simple, we just change the mechanical thermostatic head by an electrical version called an actuator. You could install those actuators on every radiator but this requires a lot of additional cabling so working with actuators on a central collector is much simpler.

The single room thermostat in the living room will disappear (Every room will have an Openmotics temperature sensor) and a dry contact will be used on the heating boiler. This contact will be used when one (or more) of the rooms require heating, the pump will start running. When the delta T is high, the boiler will start heating.

We will not interact in any other way with the heating system so we will not change heat output curve and others.

Sometimes, we get customers telling that the HVAC installer doesn't want to use any form of home automation since he had discussions regarding who's responsible when things are not working. In our type of installations, it's very simple, we just replace the thermostat heads by actuators and use 1 dry contact on the heating boiler. This makes troubleshooting very simple:

  1. Check if the actuator is opened (can be seen on the outside of the actuator)
  2. Check if the dry contact is closed

What needs to be checked?

These are the things that needs to be checked:

  • Have a collector installed with valves, on those valves, the actuator will be mounted. Make sure to use actuators that are compatible with the installed valves and that you use a NC (normally closed) version.
  • Check if your heating boiler has a dry contact. The need of this dry contact depends on the heating boiler type, some boiler types keeps the pump running so a dry contact is not needed in that case.

You can check with your HVAC installer if the above can apply to your system.

Can floor heating be used in combination with Openmotics?

Yes this is possible and exactly the same principles are applied as above. A central collector for your different floor circuits will be installed, on that collector the different actuators are installed.

Is a combination of radiators and floor heating possible by using Openmotics?


Every thermostat has 2 outputs: 1 output will be used for the floor heating (with dimmer follow function, multiple outputs will be linked to 1 output) and 1 output for radiator heating (with dimmer follow function, multiple outputs will be linked to 1 output). With the PID parameters, you can program the behavior of both outputs. For example, when the different between the setpoint and actual temperature is higher then 1 degree, both outputs will be ON, when only 0,5 degree difference, only the floor heating will continue. This will enable you to use the floor heating in normal circumstance and to use the radiators when fast heating is needed.

Can a pump delay be programmed in Openmotics?


Since an actuator takes some time to open (between 1 and 3 minutes), the dry contact (if applicable) cannot be applied until at least one actuator is open (some boilers go in error state if you switch on the pump without having any valve open). You can program the pump delay between 0 and 240 seconds. In total 8 different pump groups (will drive 8 dry contacts) can be programmed if a larger building is used with different floors and different pump circuits.

Note 1: Please always use actuators with an opening time of less than 240 seconds. Note 2: Question which type of actuator to use? Please consult Additional Material.

Does Openmotics supports cooling?


Floor systems that also supports cooling can be used in combination with Openmotics. Typically, a second dry contact is used to switch between heating and cooling.

Openmotics also supports Daikin airco systems in combination with RTD-10. For more information how to setup a floor heating system in combination with radiators and Daikin, please consult Daikin Setup.