To maintain the water level in a leaking tank, we must put in as much water as is being lost.
Similarly, to maintain the interior temperature of a room we must provide as much heat as is being lost through heat loss.
Start the film below and watch a general presentation of heating requirements.
Link to download the demonstration version or purchase
the: « Heating and Hydraulic simulator »:
http://lebatimentperformant.fr/librairie/produit/apprendre-le-chauffage-a-eau-chaude-et-l-equilibrage-hydraulique-sur-simulateur-le-simulateur-seul/520