This month, I thought to share about a very helpful device. It’s the RIB relay made by Functional Devices Inc. They manufacture several variations of this very handy enclosed relay. I carry two on my truck. The first is the RIBU1C which is a SPDT (single pole double throw) contactor with a 10 amp rating and a choice of energizing the coil with 10-30 Vac/dc or 120Vac. The second is the RIB2401B, which is also a SPDT contactor, but with a 20 amp rating and a choice of energizing the relay via 24 Vac, or 120 Vac. Before we get started, a quick review on the contactor designations: N/O (normally open) and N/C (normally closed) is how the contacts are in a “De-Energized’ state. When powered, they reverse; open becomes closed and closed becomes open. The RIBU1C appears to be quite popular, based on how many are stocked on the shelf at the supply house, so here’s a few field fixes I’ve used them on, or have seen them in use on: Zone valve end switch replacement Imagine you’re on a service call for an intermittent no heat one zone. It’s cold out, all the zones are calling, and all appears to be OK. So you take out your meter, trace and find that the end switch is bad on one of the valves. Now you could just drain down, cut out and re-sweat in a new zone valve (rather time consuming) or just wire in this RIB relay to power the relay coil when the zone valve motor gets energized, choosing the N/O contacts (yellow and orange wires) in place of the defective zone valve end switch wiring. The zone motor powers, the relay powers and the end switch closes. Priority control Oil line issues? Insufficient draft/chimney sizing? Just wire in this relay to give “Hot Water” priority. Just a caution, however—power the relay coil via the water heater’s burner motor lead. This way if the water heater goes down, the boiler will still function. If the relay coil is powered otherwise, either at the aquastat or using the power lead to the primary control, the relay will stay energized (opening the N/C contacts; blue, and yellow wires connected to the boiler’s TT on the primary control) so if the water heater goes out on safety, wiring in this fashion will prevent the boiler from starting as well. A/C ready kit end switch repair Some of the newer generation furnaces, as well as the new primary controls, come equipped with an additional transformer and terminals to add air conditioning to a furnace. In time, I’ve found some intermittent no heat calls due to a faulty end switch on these terminal boards. Utilizing a RIB relay, you can just wire the RIB relay’s orange wire to the white wire on the terminal strip coming from the thermostat, and the yellow common wire to the common side of the transformer. Then use the N/O wiring (orange, yellow) from the relay contactor to the furnace’s TT on the primary. Insufficient hot water fixes Here’s a great one that I’ve used the RIB relays on quite often: heating systems using one circulator, with zone valves for the heating and indirect water heater zones. Without the use of a multi zone panel that gives the indirect water heater priority, an insufficient hot water call is sure to happen. The RIB relay wired in parallel with the indirect water heater zone valve, wired to open and break power to the heating zone power heads, will give the indirect water heater priority. In another example, an indirect is often added to an existing system utilizing a triple relay for the heating zone. With a triple relay, a call for heat raises the boiler to the high limit—approximately 180–190°F. Without a call for heat, the reverse becomes the limit—approximately 150– 160°F. If the indirect zone is using a single switching relay that is wired to power the Z/R terminal on the triple, that is great! If not, you can accomplish this using a RIB relay that is energized when the indirect circulator is powered, sending power to the Z/R terminal and running the boiler to high limit. RIB2401B As illustrated iin the photo, this relay with its 20 amp contact is used when the load exceeds the control amp draw. I’ve found that some of these newer style switching relays cannot handle the start amp draw on lift pumps, three piece circulators and larger motors. The wiring for this configuration is to just power the relay as if you would the motor used, and utilize the relay contactor to power the motor. As you can see, these are necessary additions to our truck stock. There is great support at www.functionaldevices.com. Homework in our craft is so important and it never ends! Lastly, as I do in out the field and in my classroom, please make sure what you’re working on is de-energized first, and practice proper safety when working on electric and wiring. Stay safe, Wayne. ICM 18 ICM May/June 2017 The RIB Relay ...a great service helper Wayne Lawrence Instructor, Oilheat Comfort Corp Lawerence
ICM May-June 2017
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