to be urged outwardly by spring action in order to maintain them against the opposite sides 30 thereby holding the spring clip in place the throat 122 is aligned above slot 116 in the insulating block 115 and the throat has a size to closely accommodate the upper portion of the thermostat housing 98 when the thermostat housing is pressed into the throat 122 the legs 120 on opposite sides of the throat grip firmly against the opposite sides of the thermostat housing to hold the thermostat in place initial installation of the thermostat 26 is achieved by first connecting the thermostat tubes 84 and 110 to the respective hoses 84 and 108 the thermostat housing can then be inserted upwardly through slot 116 with one end 98a facing diagonally upwardly the compliance of the foam rubber allows it to be compressed as the thermostat is pushed up into the slot once the thermostat housing has been passed through slot 116 it is rotated into its normal upright position shown in the drawings the corner of the thermostat housing engages the end plate 34 as it is rotated and the end 98b of the thermostat housing then remains in contact with plate 34 as.