[Hai-users] RE: Temp sensors accuracy again. (Brad)

[Kenneth McLeod]

Just my 2 cents from experience:

Omnistats with remote temperature sensors will nearly always read low.  The
longer the cable run from the stat, the more off they will be, due to the
addition of the line resistance to the remote thermistor resistance.
Happily, they are easily calibrated by entering the correct offset in the
thermostat setup.  Use a precision thermometer at the sensor location and
let it stabilize for some time to get the correction.

You may find that the stand-alone temperature sensor is reading correctly
after all.  They are a different animal.  They are not just a remote
thermistor sending resistance back to the Omni panel, but have circuitry to
convert it to frequency at the unit.  (that is why they do not require
shielded cabling, as do the Omnistat remote sensors.  They are usually quite
accurate.  Sadly however, the humidity sensor portion is usually not, and
they are grossly inaccurate.  Of seven that I have tried to install, the
*best* one reads 20 percent low.  Reading 30-35 percent low has been my
typical experience, with units obtained from 2003 until now.

The only time I use them now is when HVAC control decisions depend upon
humidity input, and I have to "fudge" the setpoint off by the amount of the
error to be able to do what I need.

Ken McLeod
Integrated Home Technologies


----- Original Message ----- 

From: Brad <mailto:looney2ns at sigecom.net>
To: hai-users at tssi.com
Sent: Friday, January 13, 2006 10:19 AM

Subject: [Hai-users] Temp sensors accuracy again.

  Just installed 3 HAI temp/humidity sensors. Also installed 3 HAI OmniStats
with remote temp sensors. The Thermostat remote sensors and the
Temp/Humidity sensors are mounted on inside walls within 6 inches of each
other, each set in a different room. Temp/Humidity sensors show temps being
3-5 degrees higher than the thermostats show.

Apparently HAI STILL has not resolved the issue of the Temp/Humid sensor's
being inaccurate.

The Humidity is reading low on them as well. Very frustrating.

Anyone else seeing this?
______