Advance Sensors
This sensing element bends predictably due to unequal thermal expansion of two metals.
What is a bimetal strip?
This modern sensor converts pressure into a proportional electrical output signal.
What is a pressure transducer?
This device opens on a rise to protect equipment from excessive discharge pressures.
What is a high‑pressure control?
A thermostat that energizes cooling on a temperature rise is acting in this mode.
What is make‑on‑rise?
This device opens when motors draw excessive current or overheat, then closes again once cooled.
What is an overload protector?
Low suction pressure in a cap‑tube system that equalizes on shutdown indicates this symptom.
What is low refrigerant charge?
This device straightens under rising internal vapor pressure and is commonly used in analog gauges.
What is a Bourdon tube?
These controls replace mercury bulbs and bimetals using microprocessors and LCD displays.
What are electronic thermostats?
This operational device cycles compressors based on evaporator pressure, indirectly regulating temperature.
What is a low‑pressure control?
Slight heating of the sensing element to prevent overshoot is provided by this feature.
What is a heat anticipator?
Must never be bypassed except momentarily by qualified technicians during diagnosis.
What is a gas pressure switch?
A hot hermetic compressor reading “open windings” may actually be this condition.
What is a tripped internal thermal protector?
Used where long travel is needed, this accordion‑like sensor expands under vapor pressure.
What is a bellows?
A thermistor used here increases starting torque briefly before heating up and shutting off the assist.
What is a PTC start assist on a PSC motor?
The difference between cut‑in and cut‑out is known as this.
What is the differential?
The temperature drop below setpoint before heating airflow begins is known as this.
What is system lag?
A line‑voltage safety device on boilers that opens permanently if system pressure exceeds its factory setting.
What is a pressure relief valve?
A relief valve dripping water in a hydronic boiler system may actually indicate mis‑adjustment of this component.
What is a water‑regulating valve?
This device uses fluid boiling in a remote bulb to transmit pressure changes to a diaphragm.
What is a partially liquid/partially vapor‑filled control?
In this type of transducer, reducing plate spacing increases measured capacitance.
What is a capacitive pressure transducer?
Adjusting the cut‑in of a control automatically shifts cut‑out by an equal amount because this stays fixed.
What is the fixed differential?
These thermostats can handle 115V or 230V loads directly and must match the expected amperage.
What are line‑voltage thermostats?
To prevent a fire hazard, these controls are mounted in conduit boxes to contain arcs.
What are line‑voltage thermostats?
Overfeeding of an evaporator can occur when this sensing bulb is not insulated from ambient air.
What is an expansion‑valve sensing bulb mounted incorrectly?
These semiconductor‑based sensors can double their resistance with as little as 1°F of temperature change.
What is a thermistor?
This sensor, mounted on a multi‑compressor rack suction header, enables load‑matching staging.
What is a suction pressure transducer?
This safety control compares pump discharge and crankcase suction to determine lubrication health.
What is an oil pressure safety control (net oil pressure control)?
A cooling anticipator creates a slight rise in sensed temperature by allowing current through a high‑resistance device during off cycles.
What is a cold anticipator?
This airflow‑proving safety ensures electric heat does not energize unless duct movement is present.
What is a sail switch?
High head pressure, oil breakdown, and acid formation can result from this non‑condensable infiltration.
What is air entering a system operating in a vacuum?