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The Supco 902 series fan relays receive and control electrical signals for general purpose fan applications. This fan relay has SPST-NO, SPST-NC, SPDT-NO/NC contacts made of silver alloy and coil voltage ratings of 24VAC to 240VAC. It is suitable for use in fan applications.
Specifications
ContactsSPST-NO, SPST-NC, SPDT, 1 NO/1 NCContact materialSilver alloyPower ratings (all forms)125VAC, 18 amp resistive, 12 FLA, 60 LRA, 240/277VAC, 18 amp resistive, 8 FLA, 48 LRASpecial power ratings (form 1 and 2)125VAC, 14 FLA, 84 LRA, 277VAC, 25 amp resistivePilot ratings (all forms)3 amp, 277VAC general purpose250VA at 250VAC
277VA at 277VAC
125VA at 125VACCoil voltage rating24, 120, 208/240, 77VAC, 12, 24Coil frequency50/60 HzCoil pick-up voltageAC 85% of nominal, DC 75% of nominalCoil power ratingAD DC, Inrush 5VA 3VA, Sealed 3VA 3VA
Relay switches (also called an electrical relay or an electrical relay switch) use a small amount of power to control a larger source of power connected to electrical devices such as car motors, computers, and lighting installations. A basic relay switch has a control circuit with an electromagnetic coil and a load circuit with contacts and a lever. When current flows into the relay switch, it moves through the coil and a magnetic field is created, which causes the lever in the load circuit to move between contacts, either turning the device on or off. In a normally open (NO) relay switch, when power is supplied to the relay, the load circuit is closed and the power source connected to the relay is turned on. In a normally closed (NC) relay switch, when power is supplied to the relay, the load circuit is open and the power source connected to the relay is turned off. In other types of relay switches, non-moving parts such as transistors or semiconductors can be used as the control circuit to operate the switching mechanism. Relay switches can be controlled with an external switch, such as a light switch, or they can be connected to an automatically switched power source, such as a car ignition. One relay can operate multiple switches, and multiple relays can be operated with a single switch, with each relay operating independently from the other relays in the system.
Supco manufactures test instruments and replacement parts for heating, ventilation, air conditioning, and refrigeration systems. The company, founded in 1945, is headquartered in Allenwood, NJ.
A.K.
2025-09-06 17:15:55
Relay worked perfectly for Nest Thermostat controlling a gas fireplace. I also had to install a 24VAC transformer. Very simple configuration:1) The N/O switch contact side of the relay is connected across the gas fireplace switch leads.2) Three wire, 18-gauge thermostat cable (red, white, and blue connected to RH, W, and C respectively on the Nest thermostat) was fished through the wall. The Nest was located a few feet from the fireplace about eye-level on the wall. Fishing the wire through the wall was the hardest part of this install.3) Under the fireplace the wire is connected to the secondary 24VAC side of the transformer using the red RH power wire and the blue C common wire.4) The relay coil is connected to the white (W) control wire from of the nest thermostat, with the other side connected to the blue C common wire. In my install, the transformer and relay were tucked underneath the gas fireplace a couple of inches apart.5) Finally, the primary side of the transformer is fitted with a 120VAC cord (only needed to be about 8-inches long in my case) and plugged into 120VAC.6) On my Nest Thermostat, I had to lie to the thermostat and configure it for "electrical heat" rather than "gas furnace" ... I think. I did this and it works. Read it someplace.This is the 4th Nest Thermostat I have in my home but the only one on a gas fireplace, the other three are controlling two other furnaces, one with two zones, and no relay is required for those applications.Shipping was very fast on this product and I have absolutely no complaints. Would buy again... in fact, I'm about to use another of these relays to control my whole-home humidifier... as soon as I can figure out hot to get the additional wire run to the nest. That's another project.
Marc Emmerke
2025-08-15 13:29:36
Easy replacement for the fan relay on my furnace that was getting stuck on.
Christopher
2025-06-11 17:23:03
Installed it on my hvac system three months ago. Working good so far.
Derrick
2025-06-02 09:50:34
I am using these to use ecobee thermostats with my unconventional zone valves. Since my valves are normally-open, they require power to remain closed and the power needs cut for the valves to open. These relays do the job perfectly, and since my old thermostats used a third wire to perform this function, these relays only require two wires to do the same thing, thus freeing up the third wire for me to use as a common wire to power the thermostats.The only issue I have is that one of the two relays I purchased has failed and doesn't switch reliably. This causes that zone's valve to remain open and the rooms get far warmer than they should. Simply wiggling the wire causes the relay to audibly click and start functioning again. I have a replacement on order, so we'll see how that one fares.
R. Widebrook
2025-05-25 14:24:57
The Supco 90293 SPDT relay has two pair of controlled contactors, i.e., is double-throw. Pin pair 2 & 4 are normally closed; Pin pair 2 & 5 are normally open. (Pins 1 & 3 are the 24V coil contacts.) The coil will run on either 24VAC or 24VDC; I used 24VDC. The relay's coil may buzz if your 24VAC transformer generates "noisy" power; you'll get less buzz with better "cleaner" AC transformers. A 24VDC power-supply/wall-wart won't have any buzzing. I used this relay to run a millivolt gas fireplace valve with a Nest thermostat: the 24V supply operated both the Nest and the relay, while isolating the millivolt gas valve from the 24V required by the Nest.
The PC Maven
2025-04-17 16:10:18
I used this in my heat only 2-wire system to add a "C" wire to power the Nest Thermostat.Although the Nest worked without the "C" wire, it was temperamental, especially when the Nest called for heat often. As the Nest only pulls power from the two wires when furnace is NOT calling for heat, the Nest would be erratic if the heater was on often, and the Nest could not get enough power.This little relay solved the problem. By wiring it in with the 24VAC transformer in the furnace, and sharing one of the leads with the "C" connection in the Nest, my Nest now always has power, even when furnace is calling for heat.It has performed flawlessly all winter. No noticeable noise other than a very slight "click" when it energizes, but this happens at the same time the other furnace relay clicks, so it's barely noticeable.Bottom line... if you need to add a "C" wire to a 2-wire heating system, this works like a charm!
Tom L.
2025-04-06 17:57:30
Relay installed between nest thermostat and gas boiler. After 2 months of use, one morning woke up to find house at 80 degs and still calling for heat with a thermostat setting of 68! Come to find out relay stuck on. I opened relay and contacts were in perfect condition…Is there suppose to be a return spring to push contact open when coil is off? The was none. If coil pulls contact closed, what pushes it away when coil is off. Switching to RIB
Fred's Creek
2025-03-31 13:17:29
Works exactly as I expected. Used as a relay on my furnace to control the humidifier. Perfect
hat
2025-03-27 18:26:10
Good, works as described
rural ontario
2025-03-02 16:30:53
nothing fancy , working so far , fast delivery.
Terry T.
2025-02-19 16:28:09
Wanted to add a smart thermostat to my 40 year old furnace that would also allow me to turn on the fan from the stat; the furnace only has a heat limit switch with manual "summer" button, no control board. So spliced this into the wiring of the 'summer' button, for remote switching. Works great, no problems, responsive and sturdy.
Bordridr
2025-02-18 17:10:00
Worked for a few weeks and then failed. I do not recommend using this.
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