I have an older high efficiency gas boiler and have had it and the thermostat inspected within the last few years. The thermostat is an analog dial. The house has radiator heat. The boiler kicks on intermittently when the thermostat shows that the house is 4-5 degrees above the set temperature. Is this a design feature of high efficiency boilers since it may take a while to bring the house up to temp with radiators or is there something wrong with the thermostat or boiler control? Last night I fired my woodstove and could hear the boiler run for a long time although the tstat was set on 64 and its thermometer showed 70. The boiler wouldn't shut off until I turned the tstat down to 60.