What is this white box item on underfloor heating manifold? Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

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Hi

I have a wet UFH manifold that has recently been wired to a heatmister system.

The heatmister system is working perfectly but the UFH system keeps locking out. I then have to press the reset button on a white box. This usually, (but not always) will allow the UFH pump and port valve to activate.

The boiler is fine, the port valve to the upstairs radiators works normally when the ufh has tripped.

Can anyone help me with two areas..
1. What is this white box on the manifold?
2. How can I solve the problem?

Thanks