Central heating not bringing room to temperature setting

[Lizard]

Going back to the winter I found in one of the rooms the central heating was not bringing the room to the termostat controller setting in a reasonable time.

I note that the radiator remained very hot and the temperature was not reached even after a four hour period.  Setting at 20 degrees C.  The radiator has no TRV installed. 

I had reported this under snagging and have not been given a suitable answer as to why, only some people feel the cold more than others - completely ignoring the fact that this is about the time taken to get near to the room desired temperature and not achieving it in a reasonable time frame. 

Could this be the size of the radator or lack of insulation?
Three exteranal walls and two windows. Would this be reasonable to expect the developer to investigate and repair, or is it just tough the controller and radiator is install and working.

[New Home Expert]

Who is the housebuilder?

The radiator gets hot so the issue is not with the central heating not working.

It could be the radiator is undersize but I would very much suspect a lack of or missing insulation.
You will need to have a thermal imaging survey done to prove this beyond question.
Ask your housebuilder to investigate and point out if they do not you will get a survey done and the builder to pay for it if insulation is proved to be missing.

[Maxell]

It would be unusual for a radiator not to have a TRV fitted, unless the thermostat is in the same room.
The room where the thermostat is sited will control the boiler. Systems should be balanced so thermostat room is last to heat up .
Balancing a system is very rarely carried out on new build as most systems perform well.
I would question no trv .

[New Home Expert]

At least one room on each floor should not have a TRV fitted to allow circulation.
On the ground floor it is indeed usually where the thermostat is fitted.
It is also usual for bathrooms to not have a TRV fitted as these rooms need to be a little warmer.

[Lizard]

Thanks in advance for your futher responses

The developer was originally Keepmoat but changed to Engie - but I believe they all are Keepmoat.

The controller is in the same room as the radiator I mentioned, the system has one controller for the downstairs which I understand regulates the downstairs heat.  Additionally the system has another controlller upstairs which regulates the upstairs set of radators.  The upstairs and downstairs heating work independanly, one on at a time or both together.

Re- the survey any idea on typicals costs.

Would I be able to get someone independently to check if the radatior in the room has been sized correctly - say someone like British Gas.

[Maxell]

So the thermostat was set to 20 degrees, the radiator was hot to the touch for 4 hours and I assume the boiler was fired up for 4 hours too as  the room never  reached  temperature.
Something is wrong with the system or controllers.

[New Home Expert]

Radiator size calculator

[Lizard]

Thank you