A 10-way heating manifold

Integrating Heatmiser underfloor heating with a Vaillant central heating system

Integrating Heatmiser underfloor heating with a Vaillant central heating system

Today we’re talking about central heating systems. They have come a long way since the old-school single thermostat located in a hallway or upstairs landing. Today’s central heating systems allow for much more targeted heating, both physically and virtually via a whole host of apps and manufacturers. Not only is this good news for the environment, but also your pocket!

In this post we’re looking at how to integrate 2 manufacturers: Heatmiser and Vaillant. In this customer’s home, we needed to supply his new extension with underfloor heating. In the existing part of the property was a Vaillant system including Ambisense TRVs, and various room stats to control the existing heating loops. Unfortunately Vaillant didn’t offer a suitable product, and so we went with our favourite manufacturer, Heatmiser.

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Part 1: an overview of the Vaillant setup

The customer’s new extension required an extra heating loop to be installed for the addition of underfloor heating. The existing installation had two: one for radiators throughout the property and one for underfloor heating in the kitchen. The control of the Vaillant Ecotec boiler for these heating loops, plus the separate hot water cylinder was via a Vaillant VR70. This unit only allows for a maximum of two loops, therefore as well as the extra pipework, we also needed to upgrade this to a VR71 unit. This provided us with the extra heating loop connections required to control the boiler.

The system monitors both flow temperature leaving the boiler and external temperature to adjust the boilers heating curve to make it as efficient as it can be. The VR71 has inputs for temperature sensors/probes for each loop. It provides switch inputs to fire the boiler and open zones valves for the relevant loop as required: although in this case two of the three loops were being controlled remotely. It was only our new Heatmiser addition which would be using a switch input to fire the boiler (more on this below). The existing radiator loop and underfloor loop would be controlled by Ambisense battery-powered TRVs and a VR91 roomstat respectively – the setup for these devices is explained below.

The VR71 and Ecotec boiler communicate via a 24V bus connection rather than the tradition 230V switched live connection. This bus connection is required for the Ambisense TRVs to work with the system. A VR920 unit is required to receive data from the TRVs and to all app control via the VRC700 app.

Finally, all the programming for the new wiring centre is done via the main system controller: the VRC700. This controller can also be used as a room stat, however in this case it was not required to function in this way.

Part 2: programing the VR71 with the VRC700

Using the VRC700 programmer, we can specify exactly what we want heating/zone 1, 2 and 3 to do: in this case they are all heating loops. We can also select how we want to control the firing of the boiler for each zone. In this instance, zone 1 was the radiators throughout the property. The system had previously not been set up correctly: the Ambisense TRVs were not calling for heat individually as they should and were simply acting as radiator valves. After adjusting some installer settings and installing a temperature sensor on the flow pipework for this loop we were able to remedy this problem: the individual TRVs now call for heat if required.

The second zone was our new underfloor heating loop. In the VRC700 setting we specified no controller in the zone settings: this would be taken care of by the UH8 wiring centre and Heatmiser room stats (more on that below).

The installer settings on this unit allow you to check which loop may be calling for heat, or not, which is handy for double checking that all options have been set correctly.

Part 3: integrating the new Heatmiser UH8 with the Vaillant system

Now we come to the addition of the underfloor heating control to the existing system. The 10-way manifold was controlled via a Heatmiser UH8 wiring centre and Heatmiser Neo wired thermostats. With the addition of the Neohub, the customer could also have remote control via the Heatmiser Neo app.

The UH8 provides up to 8 zones of heating, in this example we’re only using 4: cinema, landing, and two toilets.

The only slight hurdle for us here was that the UH8 provides a closed signal when calling for heat to fire the boiler. The switch input on the VR71 wiring centre requires a volt-free open signal to trigger the boiler. We got around this by using a switched live from the UH8 to energise a coil feed on a normal closed relay. When the coil feed was energised, the relay opens; sends this open signal to the VR71 and fires the boiler for the new heating loop.


You might like to check out our other posts on heating control with Heatmiser products, and please drop us a line if you’d like to discuss any smart heating installation at your property.