Can multiple occupancy sensors be used to control a domestic hot water return pump system?
A sensor in each of three bathroom locations wired parallel to start one common low wattage return pump.
A temperature switch would interrupt circuit when return water temp reaches 100 deg F.
Do the sensors need to steal power to run from a closed circuit? This closed circuit is not there in this case.
Electrical – Multiple Occupancy Sensors to control hot water return pump
electrical
Related Solutions
You can probably replace the switches with those sensors, but you're going to have to do some creative wiring to work around the fact that they're not 3-way switches, but the switches you're replacing with them are. You'll likely end up with the light being on whenever either of the switches is on. You also might run into trouble if they ran the 3-way switches as a switch loop (no neutral in box), because "smart switches" like these require a neutral so they can use power for themselves to decide when to switch on and off.
Here's what the difference between these wiring schemes looks like if you draw it out:
Also note that those occupancy sensors still have a hard-on switch, so your tenants can still just leave the lights on. You might want to look instead at vacancy sensors. (An example vacancy sensor is Cooper Wiring Devices K01-400RW-L, but note that it does not handle CFLs, just incandescents.) These, you tap to turn them on, and they turn themselves off automatically when everyone's gone. That sounds more like what you want.
The how for switch #1 depends again on how they wired your #1 switches and the light they control together. If you diagram out the connections, it becomes straightforward. Until you have enough info to diagram it out, you don't have enough info to rewire it, either.
As an aside, all the exterior stairwell lights I've seen in apartment complexes were on timers. They'd come on around dark and flip off in the morning. I knew they were timers rather than photosensors because a couple times a year they'd end up slightly out of sync with actual daylight hours, but if these are in fact exterior lights, putting them on a photosensor and disabling the switches entirely might be an option.
I was only able to get it to work with two companion switches. The Lutron series does not work properly with two occupancy sensors. My goal was to get the apt on top and the entry way to have the lights turn on when the tenant or person entering opens the door.
I like the lutron; works really well and turns on only when needed if its truly dark.
This is how its the four way with companions would be wired
(source: tyronnephotography.com)
See the diagram and the description for 4-way.
http://www.lutron.com/TechnicalDocumentLibrary/048435.pdf
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Best Answer
I am assuming the sensors in the bathrooms are low voltage, say 24V, and rated OK for parallel operation. Also assuming that the relay that runs the pump is the same low voltage. Generally the sensors will have three wires, positive in, negative / common in, and switched out. Let's say it's black, white, and red.
In the basement, you'd connect the all the blacks from the occupancy sensors to 24V+, all the whites to common, and all the reds to run them in parallel.
Then to run in series with the temperature sensor, you'd tie the reds to the black of the temperature sensor, the white of the temperature sensor to the other whites, and the red of the temperature sensor to the coil / primaray + terminal of the relay that runs the pump.
The white of the coil of the relay that runs the pump would tie to all the other whites. The secondary / contacts of the relay would switch power form the pump.