SRH2 Diagnostic Digital Psychrometer with Target Superheat and Target Evaporator Exit Temperature

BREA, Calif., May 29, 2008 -- Fieldpiece Instruments, manufacturer of professional-grade instruments for field service, introduces the SRH2 Standalone Diagnostic Psychrometer. The SRH2 not only performs the typical functions of a digital psychrometer (DB, WB, %RH, DP), but also helps the HVAC technician analyze an air conditioning system by automatically calculating target superheat (TSH) and target evaporator exit temperature (TEET). Superheat is the best method for correctly charging a fixed orifice air conditioning system. The techs need TEET to insure proper air flow across the evaporator.

“This is the only psychrometer that displays TSH and TEET, two parameters a technician needs to properly service most air conditioners,” says Rey Harju, President of Fieldpiece Instruments. “Because it’s difficult to calculate these parameters manually, many technicians skip this step altogether. Now we’ve made it easier for them to do the job right.”

The SRH2 has two sets of sensors. The sensors built-into the body are great for ambient air. The plug-in K-type thermocouples are for hard to reach spots. TSH typically uses the built-in sensors while TEET uses the plug-in sensors to measure the air going through the evaporator. The technician chooses which works best for him.

The SRH2 includes two thermocouples. The ATA1 thermocouple measures dry bulb and the ATWB1 thermocouple measures wet bulb. In both cases, Fieldpiece’s alligator clip design holds the thermocouple in place.

The SRH2 case is plastic and is surrounded by a solid rubber holster to protect it from drops. The display is backlit for reading in dark areas. A magnetic hanger on the back makes everything easier. Other features of the SRH2 are Auto Power Off after 15 minutes of inactivity and MAX/MIN/Hold functions.

The SRH2 is priced competitively at $149 (trade), which includes the Psychrometer, the ATA1 K-Type Thermocouple, ATWB1 K-Type Thermocouple, and battery.

Calculating Target Superheat is important because it is the first step in diagnosing charge related fixed orifice A/C system problems. The superheat needed to keep an air conditioner running depends on the entering dry bulb and indoor return wet bulb. Up to now, a technician has had to take two measurements, and then look up target superheat on a chart. The SRH2 calculates the target superheat automatically. A technician compares the target superheat to actual superheat on a fixed orifice system to determine if the system is properly charged. The actual superheat should be within five degrees of target superheat for a fixed orifice system. A properly charged system prevents damage to the compressor and runs more efficiently.

The TEET diagnostic test (also known as “temperature drop” , “temperature split” or “delta T”) gives an indication of proper airflow to the system. The technician uses the included thermocouples to measure the wet bulb and the dry bulb temperature of the air entering the evaporator by clipping each thermocouple onto the air filter just in front of the evaporator. Then he measures the air temperature coming out of the evaporator. If the actual TEET is 3°F less than the Target TEET check for low airflow. If the actual TEET is more than 3°F above the Target TEET it is an indication of low capacity, and occasionally high airflow.

Client Contact: Russell Harju – Product Manager, (714) 634.1844
Press Contact: Beverly Steinberg, (714) 777-2760


Formed in 1989, Orange County, Calif.-based Fieldpiece Instruments has become the testing tool company that HVACR professionals trust. Because Fieldpiece focuses only on the HVACR industry, all products are developed to solve real world HVACR problems. Not only do the tools have the right functions and features, but also techs can trust them to work where and when they need them, because they withstand the use and abuse techs in the HVACR field dish out. Fieldpiece constantly develops new tools that allow HVACR professionals to do more than they otherwise could, increasing the tech’s capability and billable hours. For more information please visit our website at or call 714.634.1844.

  • Created: Thu, January 17, 2013