Multiple controller systems



I have a Vaillant ecoTech 637 combi boiler.

From that I have a two controllers:

  1. HoneyWell ST9100C w THR872C Thermostat that controls the underfloor heating in the kitchen
  2. Honeywell ST9400C with a wall mounted dial thermostat that controls the hot water and the radiators for the remainder of the house.

I bought the wirelsss starter kit on Amazon as a black Friday deal w/o any research (the deal was running out) and not looking at my heating system as I was away from home.

Did I get the right thing? I assume that I need to change use the one I bought to replace the ST9400C / old thermostat. What do I need to do for the underfloor heating?

It is all very confusing, especially as I have recently returned home after 4 years in the US and not so familiar with the system here...