I have wet underfloor heating in my new extension and radiators in the rest of the house. In all there is 5 double panel radiators and 4 single panel ones.

There are two RF switches connected to the combi condensing boiler (vailant ecotec plus 838). There are two wireless thermostats. One is connected to the RF switch which controls the underfloor heating and the other is connected to the RF switch which controls the radiators.

There are 2 x Honeywell two port valves. One for the radiators and one for the Underfloor heating.

I know my gas safe engineer needed help connecting the wiring for there to be two RF switches and for them to be able to be turned on independently from two separate thermostats.

I have noticed that sometimes for many hours even after the boiler is not on anymore (room temperature higher than setting on thermostat) the radiators in the house remain warm. Like today The radiators have been warm since morning to late afternoon/evening. Not warm like when the boiler is on, but warm. The boiler says the temperature is around 45-50 degrees.

Also the boiler sometimes turns on (not when using hot water) and the radiator icon shows Even though the thermostats do not have the flame icon and the temperature setting is still lower than the room temperature.

The are no time settings on the thermostats, it is on manual mode.

Is this normal? As I do not remember my radiators doing anything like this before when we just had one RF switch and no underfloor heating

It's possible the Radiator zone valve is jamming open or the ZV micro switch is jamming ON.
Next time it happens, check the lever on both zone valves.
HTH

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I wonder if the rads are leeching heat from the UFH?

We need to know how it's been piped and wired really

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