Velbus temp control system

I have a standard boiler on a flow-trough principle (doorstroom gaswandketel) and I want to run it with velbus. How do I make the internal circulation pump for heating work. In other words how do I let my boiler know that I want heating? My boiler comes with a controler (thermostat) that connects with its own bus protocol.

Do I need a new and special boiler? Do I need to start modifying my boiler?

any and all help is welcomed

What’s the brand of your heater?

it’s a vaillant ecoTec

The problem of the most heaters is that they use there own protocol in combination with there thermostats. The only solution they often provide is a normal sitch contact but in that case u lose the modulation character of your heater.
Another option is to make your heater weather dependant and use the velbus modules only to control the zone valves. In this mode your heater will be modulating and your pump is running all the time (you’ll need a bypass valve to have circulation all the time). The heater will look at the inlet/outlet temperature difference and heat up when there’s deviation (meaning a zone valve is open). Depending the weather outside, the circuit is at a higher or lower temperature.

  • benefits of the first system (open closed contact): your heater will only work when asked for and your pump isn’t running all the time

  • disadvantages: no modulation, the heater is running at full power every time

  • benefits of the second system (weather control): your heater is modulating and the right temperature of your system is given by the outside temerature.

  • disadvantages: pump is always running

In my case I 'm going to use the second option (I’m using a Junkers heater) otherwise I 'll have problems with the solar modules of the system wich uses the same protocol (heatronic) and in that case I’m not able to use the open/close contact.

I’ll hope this makes it a bit clear? If you 've questions, the best way is to go to your local dealer and discuss the best options in your case.

I also use the same heater to heat my boiler (buffervat). I’m planning to use 1 relay to switch the heat demand to the heater on or off. Inside the heater is a connection that is normally bridged or connected to a thermostat, in this case i will connect it to a relay. With questions about this heater itself, feel free to ask…