Help Please!!!

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paawwlwall

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This may be a stupid question but I can't find what I am looking for maybe someone can point me in the right direction.

This is my scenario....

I am trying to power two peaces of equipment with a single power source. I have two small electrical boilers and only have space in my panel to power one. The Client is wanting to power both peaces of equipment independently from each other but never at the same time basically one will be running for a month and then the other will run for the next month. I need the "switch" to be able to receive a signal from a controller and tell it which peace of equipment to operate. I am thinking of this as a "reverse automatic transfer switch" if there is such a thing but I need something that basically does the opposite of a transfer switch.

Hopefully this is written clear enough to understand what I am trying to do.

Thanks for the help!!
 
Could use a contactor with both normally-open and normally-close contacts; could use two N.O. contactors and another relay with a NC; could use two separate outputs from the controller. I think you can also get packaged controller units to do this (for on-demand water heaters). How big are these heaters? Are you allowed to put them on a single feed (both code and the manufacturer's instructions)?
 
How about a latch relay? You can buy one and put it in a small jbox with a couple pushbuttons to select which boiler gets fed for < $100. gives you a nice place to wire to as well.

Personally, I don't think much of the idea. if you are going to go to the trouble to shut down the power to the panel board to install the new CB, you might as well make it a larger CB and feed it to a new subpanel so you will have some room down the road to add additional circuits.
 
As others have stated, a contactor will serve your purpose. Though others have made some additional recommendations, I think more info on controller functions and outputs is necessary before more specific recommendations can be made. A latching contactor may work for you, but these typically require a pulse to switch contact states. If your controller is on-off, you will need at least one additional interfacing device, perhaps a relay with pulse function. Additionally have to consider whether controller has a mode where both boilers are deenergized, which would require two contactors.
 
jumper said:
Should be time controlled, so customer does not have to remember. How? I dunno.

A month seems a tad long for cycling, again I dunno.
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I agree, a month does seem like a long time for cycling. A facility I work at has three steam boilers. There are always two boilers online and one offline. Example: Boiler #1 is online two weeks off one week. This is done manually .
 
petersonra said:
you might as well make it a larger CB and feed it to a new subpanel so you will have some room down the road to add additional circuits.
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My thoughts as well.

Need to also consider whether or not both will need to operate at same time, at very least possibly one needs to heat up to operating temp before transfering to other.

How is steam/water output transfered when switching from one unit to the other? If you want automatic transfer of power you will need automatic transfering valves on the output also, I would think.
 
jumper said:
Should be time controlled, so customer does not have to remember. How? I dunno. .....
Click to expand...
Programable time clock should do the trick.

I like Tom's idea though. The boilers could be switched in variety of ways- number of days, run time hours, number of cycles, override if the scheduled boiller fails, etc. And all of it could be monitored.
 
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