Calibration Data in Your EMS

What if the temperature your thermostat displays is not the true room temperature?

During the heating season, if the thermostat “thinks” the room is at the 72°F/22°C set point, but the room temperature is actually 76°F/25°C, you’re wasting energy. On the other hand, if the room temperature is actually 62°F/17°C, the room is uncomfortably cool. As a hotelier, you don’t want either situation.

Defining the New Normal

Unless your thermostat is in an inappropriate place for reading the room temperature, the  thermistor (the temperature sensor inside the thermostat) is askew. Recalibrating the thermostat defines its “new normal”.

Do YOU know which of your thermostats have been recalibrated?

EMS systems can track degrees calibrated from the factory setting. So, let’s say you have 100 thermostats at your property. At the time of installation, the calibration for all of them is zero. Over time, maintenance adjusts the calibration in some of the rooms. Some are recalibrated to a mere 2° difference. Others are calibrated to a significant 5° difference, and one of those rooms is calibrated to a whopping 12° difference.

Symptom of a Larger Problem?

Recalibration is a useful tool, but sometimes the temperature discrepancy is a symptom of a larger problem, as explained by Jacob Hittler, Telkonet Support Manager and formerly one of Telkonet’s most experienced EMS installers.

A robust energy management system tracks the calibration degrees for each thermostat at the property. As an EMS user, part of your routine maintenance should be to view a list of all thermostats and sort them by calibration degrees. The thermostats with the highest calibration degrees are warning flags that something in the room could be amiss. What caused the thermistor to be calibrated to read twelve degrees off?

Set Point Differential

To further investigate, take a look at the “Set Point Differential” (that is, the difference between set point and current temperature) for those thermostats. That data can confirm if something is amiss in those rooms if they are occupied, the thermostat relays are active, and it has not been unoccupied in the last 15 minutes. (Conveniently, your EMS may be able to list this information all on the same screen.)

Get in Front of the Problem

Jacob recommends maintenance personnel visit those rooms to assess a potential problem. The most common causes for wide temperature swings include something as simple as thermistors caked with dust and debris. Simply removing the debris is an easy (and cheap!) fix.

Another reason is the thermostat location. Is the thermostat located on an outside wall? Is there hot or cold air in the wall that can be plugged with some peel and stick pipe insulation from the hardware store? Perhaps an air leak? Is the thermostat in the pathway of direct airflow? Perhaps relocating the thermostat is warranted.

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