How to Use a Dry Contact Input RIB Relay in a Central Vacuum System Application

January 26, 2021
Tech Tuesday

In a recent technical support call, a customer of ours had a unique application. The customer was a contractor, and he had been tasked with getting an old central vacuum system back in working order for a homeowner. The homeowner knew when they purchased the home that the central vacuum was not functioning, and that was the only information our customer was given.

After some troubleshooting, our customer informed the homeowner that the vacuum still worked, but there was an issue with the control module. He was unable to find a replacement for the controller, so he told the customer that they would probably need to get a new vacuum/controller. The homeowner did not want to spend that much money, and they asked him if there was any other way to get it working.

He did some more investigating and found that the vacuum hose connections throughout the home each had a small reed switch built in, and the hose that attached to them had a small magnet built in. When the hose was inserted into the inlet, the reed switch was actuated by the magnet, and that sent a contact closure to the control module. He also figured out a way to bypass the control module, so that the vacuum would run whenever it was powered. Now he just needed a way to get a contact closure from any of the hose inlets to send power to the vacuum. That is where the Dry Contact Input RIB® Relay came into play.

I told him that he could take all the reed switch outputs, wire them in parallel, and connect them to the Dry Contact Input of our RIB01BDC. Then he would use the Normally Open (NO) relay contact to send power to the vacuum. That way, if the hose were inserted into any of the inlets, the RIB® would see the contact closure and close its NO contact. This would power the vacuum. The diagram below shows how this would be wired.

If you have a unique application that you cannot seem to find a solution for, give us a call, and maybe we can help you out. Our relays are versatile and come in many configurations, so there is a good chance we have what you need.


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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.