Room Temperature

I don’t think this is any fault or problem with Tado itself but Just in general regarding room temperature.

Currently in the living room with all doors closed off to half and joining dining room. Relativity small room. We have had radiator on for almost two hours with the smart radiator thermostat, but it’s not going anywhere past 18c’ - (it’s set to 20c’)

When I use a 2.5kw electric heater with built in digital thermostat It can ramp up the temperature quick and easy to 22c.

The heater is currently off but also reading 18c in line with the Tado smart radiator valve (which is set to -1c offset).

So basically I’m confused on why the room isn’t heating up to 20c’ with the radiator over the past almost 2 hours.

The dial on my alpha combi boiler is set to 5 out of 9 so I’m unsure if higher would help. I’m just unsure because I’m new to Tado and only now just seeing temperature by using the radiator only.