Saving Energy When an Overhead Door Is Open

July 28, 2020
Tech Tuesday

When the weather gets extremely hot or extremely cold, people notice it in their pocketbooks as well as on their skin. Finding ways to save energy on heating and cooling during these times can make a noticeable impact on electric bills. One question geared toward this end comes up occasionally in technical support calls and emails, especially this time of year. “How do I turn off the air conditioning in my shop when someone leaves the overhead door open?”

Problem: Many workshops have overhead doors, which can be left open intentionally or unintentionally. No matter the reason, it makes sense to stop running the air conditioning in the space during this time. It is a waste of energy and money, and in an extreme situation, could cause failure of the air conditioner itself. Fortunately, this can be fixed without much effort or a high sticker price.

Solution: Use a Time Delay, Dry Contact Input RIB® Relay and a Magnetic Door Switch. While a normal Dry Contact Input RIB® Relay could work in this application as well, the time delay version is the best option. The time delay version will allow the overhead door to open and close, and it will only turn off the air conditioning if the door is left open longer than the time set in the device. The following diagram shows a basic application, which is explained below.

The diagram shows the RIBD01BDC time delay, dry contact input relay, which requires constant 120 Vac power. For this application, it will need to be put into the Delay on Break (DOB) mode (see product datasheet for details), and the timer can be set up to 30 minutes. While the magnetic switch is closed (overhead door closed), the Load, which represents the air conditioner, will have power. Once the switch opens, the timer will start. If the magnetic switch is still open after the timer expires, the normally open contact of the RIBD01BDC will open and break power to the Load. We also offer the RIBD02BDC, which can be powered by 208-277 Vac and has the same contact ratings as the 120 Vac version. The magnetic switch shown can be any type of dry contact closure that is available, and this application can apply to any type of door or window that may get left open.

With this setup, you can rest easy knowing that you are not cooling or heating the great outdoors, wasting money and energy, and potentially damaging your equipment. As always, check the datasheet for product ratings and capabilities and call us if you have a question.

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About the Author

Henry Smith is a design engineer at Functional Devices, Inc. He has a BS EET obtained from Purdue University in 2014 and a lifelong interest in electronics. As an engineer at Functional Devices, he gets to provide Technical Support to our customers, from distributors to specifying engineers and installers.

Henry enjoys providing tech support, as it allows our company to assist at every level of our product’s lifecycle and exposes us to interesting and unique applications. While not every technical question is unique, even answering a simple question or providing someone with the information in a timely manner can go a long way to helping him or her meet a deadline.