Some muppets think that by removing t,stat that engine runs cooler,all it does is to mess with the circulation and causes hot spots around the cylinder head.Tstat`s are designed to create pressure on the hot side,the higher the pressure the higher the boiling point,and to force hot water through the heater matrix.Also add a wetting agent to the coolant,this aids the transfer of heat from the metal to the water.
regards Vic