I have three electric heaters installed on the 1st floor. All three heaters are running off of 1 thermostat the heaters keep turning off an on not allowing the 1st floor to get warm. The heaters are as follows a 1500,1500 and 2000 watts. These heaters are not running using a relay is this OK? We are using 10/2 wire and a 30 circuit breaker. Does anyone have any suggestions?