Last weekend the temperature in the house dropped below 17C so I put the heating on to get the chill off (outside temperature was around 9C overnight). However it took almost 2 hours to get to 19C, and another hour to 20C! I don't think this is right for a new build so something must be wrong!
Some facts on the house:
-The house is a 4-bed detached with gas central heating.
-I've checked the radiator sizes and they're sized correctly for the rooms.
-The radiators are all hot to the touch with no cold spot.
-I've also checked the temperature at the flow & return pipes at the radiators (by touching with hands), and I can feel a distinct temperature difference so I think the balance is ok.
-The flow temp at the boiler is set to 70C
-The air permeability of the house is 4.7, which is within the requirement of 5
Everything seems to be fine on paper, which doesn't explain why the house takes so long to heat up!?
One thing I did notice is that during the heatwave this summer, the temp inside the house seems to be lower than the outside temp. I could feel a temp drop as soon as I enter the house, only managed to bring the inside temp up after opening all the windows and patio doors.
Can anyone suggest what is wrong with my house?