A little out of the ordinary, 2 sources, 1 load.


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Old 09-06-15, 03:24 PM
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Lightbulb A little out of the ordinary, 2 sources, 1 load.

I have a thought about doing something that is a little out of the ordinary.
I would like to control a single fan (the shared load) from 2 separate switches (both a thermostat and a timer.) This is simple enough if the 2 switches do nothing else, but the trick here is each switch controls different additional loads (heating elements) that need to be independently switched.
To summarize, the switch scenarios are:
Switch1, Switch2, Element1, Element2,Fan
Off, Off, Off, Off, Off
On, Off, On, Off, On
Off, On, Off, On, On
On, On, On, On, On

Anyone know of a device, or selection of devices, that can allow this?
I.e. - 2 wire in, 1 out. Out hot if either wire in is hot, but wires in isolated from each other.

Thanks in advance for any help you can provide!
 
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Old 09-06-15, 04:07 PM
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Anyone know of a device, or selection of devices, that can allow this?
No... think of what you are trying to do.

You'd end up with a confusing mess all for what ?
 
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Old 09-06-15, 04:50 PM
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One way would be to swap both switches for double pole switches and use the extra contacts to switch the fan. The extra contacts from both switches would be in parallel so if either was on the fan would be on.

Another way would be to have two control relays with one coil across element one and the other across element two. The SPST NO contacts of each relay would be wired in parallel, with one paralleled terminal to hot and the other to the fan.

Lot of work for????
 
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Old 09-06-15, 10:33 PM
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Thanks!

Thanks CarbideTipped! I hadn't considered your approach with double pole switches, but it seems to make some sense. Unfortunately, I have a single pole thermostat and single pole timer and only 14/2 running to each from the heater.
I was originally thinking about Diodes but don't even know if such a thing exists for 120VAC. I thought about relays after my post. Thinking maybe I can get away with a single 5 pole relay with the feed to Element1 connected to NO pin and Element2 to the coil and closed pins. Fan feed from the output pin of course. Simple, no mess. :-)
To answer your ???, I have a bathroom heater with 4 configurable 450W elements and a single fan. My 44sqft bathroom doesn't need 1800W to maintain room temp, so am configuring 900W on Thermostat. Want to use the remaining 900W for a 'boost' when jumping in the shower so the room is toasty warm when stepping out of the shower. :-)
Thanks again for the constructive response.
 
 

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