Avoid Unnecessary Start-ups and Shutdowns

      During heat up the system is under maximum load and components are stressed due to temperature changes. The expansion tank temperature is elevated as hot fluid expands into it. During shut down the temperature stresses are also present and air can be drawn into the system at sealing points. These problems can be avoided by maintaining the system at constant temperature as long as possible, or by scheduling reasonably long heat up and cool down schedules. At shut down the circulation pump(s) should be left running until the system is 150 deg F or cooler. In many cases, systems are oversized leading to repeated burner cycling. This can often be avoided by de-rating the burner capacity leading to continuous firing with modulating control which causes much less wear and tear on the burner, heater and the heat transfer fluid. Do not let the system overheat – temperature alarms should be in place to shut the burner off in the event of an overshoot above the required operating temperature.