Meters for Watts and Power Factor.
I have been testing a few meters for taking watt and power factor readings. One reason I want good watt readings is to double check my TrueFlow grid CFM readings when commissioning a Bosch heat pump. By having an accurate wattage I can determine the CFM from the blower chart.
I want the power factor reading to check on motor efficiency under load.
Redfish/ Supco has the DVM 550 Wireless BlueTooth Power Clamp Meter. I haven’t tried it
Testo has the 770-3. That meter seems to be discontinued. I have one but the watt readings were unusable. They jumped around from 132 to 550 watts on the blower I tested. I don’t know if it was a defect in the meter I have or if this problem was widespread.
Here are two choices I have done well with so far:
I got the PCE-PCM 1 meter for $185 plus $15 shipping. It shipped in one day straight from Germany. I have been testing it and I like it a lot The price is amazing especially considering that it is single phase / three phase meter. The other meters I mentioned are only single phase. Note that it is a bit larger than the typical HVAC multimeter. Also be aware that it only has amp, voltage and kva related readings… no capacitance, ohms etc so it can’t take the place of a regular multimeter.
https://www.pce-instruments.com/us/measuring-instruments/test-meters/current-clamp-pce-instruments-current-clamp-pce-pcm-1-det_2132343.htm?_list=kat&_listpos=14
And here is the dark horse that has really surprised me:a $20 dollar component I got on Amazon, the CrocSee CRS-022B LCD Display.
You have to add your own alligator clips and extend the wiring on the snap around amp clamp but that should be easy for any AC tech.
The readings have been very close to the German PCE-PCM 1 meter so at this point I am very comfortable trusting the data the CRS-022B gives me., though I plan to use them both.
Remember with most HVAC motors you won’t get the correct wattage just by multiplying volts and amps unless it happens to have a power factor of 1.
volt x amps x power factor = watts.