Either Side of a
Elapsed time meters are sometimes used to help predict service intervals, and
confirm proper control operation.
BTU meters combine temperature differential and flow rate measurements to
calculate heat flow. These are generally used for monitoring purposes. (Figure 2-54)
Indicator lights are normally included on the differential thermostat to show the
availability of power and when power is being sent to the pumps. Sometimes,
remote lights and temperature displays are added to the control to make checking
on the system more convenient.
Pressure alarms have been used to alert service personnel to the need for service
in closed-loop systems. They are not currently in general use.
A BTU Meter System
2.7 COMPONENT OPERATION