Acceptable temperature delta

[nigel_greenwave]

Hi, what's an acceptable temperature delta when doing a field test between an installed space temperature sensor and a handheld temperature sensor during a service?

I'm hoping that there is a ASHRAE standard.

[PiotrJakubczyk · Accepted solution]

Probably it depend from entire device accuracy and its permissible error. If measured temperature is outside of permissible error range for your device it can be part of the problem.

Also acceptable delta temperature depend from process you are controlling. In manufacturing it is defined by production engineer /Quality team.

Reference device should have higher accuracy class than compared device.

Reference device should be intended for the same measurements as the device being checked.

Reference device should have similar measuring range.

Reference device should probably use same phenomena to measure temperature (probably there will be difference between resistive temperature sensing element and IR temperature meter)

Measurement time should be enough to stabilize readings because devices have different inertia.

Measurement environment should be same for both devices. 

Also valid calibration certificate is useful and person should be trained to use reference device. 

You also should be sure that power supply is in range for both devices... and here problems are stacking..

Probably easies solution is to take measured device to laboratory. 

I think this question is more about measurement technique, metrology than about ASHRAE.

In HVAC business if peoples are complaining device accuracy is usually not a problem. Usually problem is difference between measured temperature and perceived temperature. 

[nigel_greenwave]

Hi Piotr,

Thank you for your detailed response, it makes a lot of sense to me.