| 摘要 |
<p>ELECTRIC HEATING SYSTEM WITH PROPORTIONAL TIMER HAVING A CYCLE OF FIXED DURATION A heating system comprising a closed conduit containing a liquid which is continuously circulated through the conduit by a pump. An electrical resistance heating unit serves to heat the liquid in the conduit and heat is transferred from the liquid through a heat exchanger to a medium to be heated. A proportional timer is operably connected in the electrical circuit with the heating unit. The timer has a cycle of fixed duration composed of an "on" interval and an "off" interval, with the duration of the "on" interval being variable within the cycle. A temperature sensor senses the temperature of the liquid in the conduit and if the temperature falls below a set value, the sensor acts to operate the timer and energize the heating unit. A second temperature sensor acts to adjust the "on" interval of the timing cycle in proportion to the deviation of the liquid temperature from the temperature setting.</p> |
