we recently installed a Worcester Greenstar HE Plus combi. According to the manuel, we should set the central heating control on the boiler to "E" or maximum rated temperature for efficiency. However the old room thermostats doesn't work and none of the radiators have thermostatic values so it gets really hot when we do put it to "E". Is the best solution to install thermostatic values on all the radiators? Is it easy to install and inexpensive? Appreciate any suggestions...to save us money and energy!