Are Your Thermostat Temperature Sensors in the Wrong Place?

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Let’s suppose your Heating and Cooling equipment is in perfect health and your thermostats are internet-connected and set with a perfect schedule to maximize comfort and energy savings. You have reason to be proud and thankful! However, all of this technology is still at the mercy of a small temperature sensor that reports room temperature back to your thermostat.

A well placed temperature sensor (which might be built in to the thermostat itself, or might be a small “remote” sensor that is wired back to the thermostat) reports the temperature your guests and staff experience and allows your Heating and Cooling system to deliver the cooling or heating necessary to keep everyone happy and comfortable. A poorly placed sensor can cause HVAC equipment to run too long, not long enough, or in short bursts, all of which can cause comfort issues, wasted energy, and excessive wear and tear on your equipment.

Let’s start with some bad locations for sensing temperature:

  • Badly placed temp sensor

    Frequently opened doors (including exterior doors and Walk-In Coolers, like in the above picture) allow air to hit the thermostat temperature sensor and skew readings.

    Over or behind equipment that kicks off hot or cold air (cooking equipment, refrigeration equipment, near walk-in doors, etc.)
  • Near exterior doors that are often opened (for example, the kitchen door might be propped open for deliveries
  • On the ceiling
  • In direct sunlight
  • Directly under ceiling fans
  • Too close to Heating and Cooling supply ducts
  • In return ductwork, especially if you have high ceilings
Temp sensor under supply duct

If your temperature sensor is too close to supply ducts, the reported room temperature will swing up and down as Heating and Cooling equipment turns on and off.

Another common issue is that the hole in the wall for the temperature sensor wires is not properly sealed, allowing air to come through the wall and blow on the back of the temperature sensor, thus skewing readings. This issue is particularly problematic on exterior walls where the air leaking through might be influenced by the outside air temperature or sun hitting the building.

So where should you place temperature sensors in order to accurately report room temperature and properly control Heating and Cooling equipment? About 5 feet high on a column or interior wall in a central location with good circulation (though not too close to supply ductwork), with no hot or cold equipment nearby.

Checking temperature sensor placement whenever you are on-site is a great idea: it should only take a minute to find each sensor, and if you can’t find the sensor, it’s probably not in a good spot! Equipment moves or is added to locations over time, so it’s important to check periodically even if the sensor was originally placed properly. Of course, you can’t visit every location on a regular basis, so that is where an internet-connected system like SiteSage can really help.

SiteSage detects poorly located temp sensors

Remote access to thermostat and energy data reveals some patterns that indicate poorly placed temperature sensors. In this case, the thermostat is too close to a supply duct so the reported room temperature jumps up and down whenever the Heating and Cooling unit runs. This rapid cycling is uncomfortable and puts a lot of wear and tear on the Heating and Cooling unit.

Having remote access to thermostat and Heating and Cooling equipment data (such as energy use and supply duct temperature) allows easy access to check for signs of poor sensor placement, such as consistently hot or cold readings you know are not representative of the rest of the space or rapid cycling in temperature as the Heating and Cooling equipment turns on and off.

To recap:

  • Even the best Heating and Cooling system and thermostat can be problematic if its temperature sensor is poorly placed. As part of our Managed Services offering, Powerhouse Dynamics catalogs existing sensor locations when we install SiteSage and escalates problematic sensors to be moved.
  • The best location for sensors is on an interior wall with good circulation and no hot or cold equipment nearby.
  • Checking sensor readings on a regular basis, either on-site or via an internet connected Energy Management System (EMS), is important to keep occupants comfortable, reduce energy waste, and keep Heating and Cooling equipment healthy.

Learn more about SiteSage and the value of remote data monitoring and HVAC control to drive savings and comfort across your enterprise.

Interested in seeing how SiteSage could work for you? We’ll be happy to show you!