FYI
I have been using an HSM-100 sensor to monitor my SPA temperature
for 3 years now and it has worked fine (spa has seen days over 40 and
winters of minus 35 outside). SPA is 500 mile away so it’s great to know
ahead of time when it fails. Bonus two spas in the area have been stolen
in mid day so the motion sensor could also prove useful someday !
Richard.
Note: Sensor is inside SPA housing and 24 inches from ground (on ozonator)
I placed a zwave wall switch as close as possible to relay the signal.