bwk
newbie
Reged: 02/08/10
Posts: 4
Loc: Florida
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Hi,
I'm in the process of building a solar hot-water system. My temperature controller supplies 110v to the circulator pump, whenever it needs to run.
Heres the problem; I recently aquired a circulator pump that operates on 220v. I thought that I'd simply run one of the 110v legs through the controller and use that as a on/off switch to the pump.
My son-in-law said that was a NO NO, and that I'd damage/burn up the motor by allowing 110v to stay on constantly.
My first question is: Is he correct?
My second question is: If he IS correct, what kind of relay/gizmo do I need to turn on 220v to the motor, using my 110v
controller?
If you know the answer to the 2nd question, please keep your response as simple as possible, as I'm a beekeeper, not an electronics engineer.
Thanks,
Billy
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CabinConnection
Big Foot
Reged: 01/20/04
Posts: 18899
Loc: The Indianhead's Left Nostril....
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Post deleted by CabinConnection
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bwk
newbie
Reged: 02/08/10
Posts: 4
Loc: Florida
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Cabin,
I just looked, and no, there are no screws/connections allowing that. All the wires go directly into the motor. 
Thank you,
Billy
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CabinConnection
Big Foot
Reged: 01/20/04
Posts: 18899
Loc: The Indianhead's Left Nostril....
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Well then, wait for the electricians (I'm not) to show up and comment. I was just hoping your solution would be easy - that being to swap a couple of leads inside the motor itself. 
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3phase
Electrician
Reged: 09/09/02
Posts: 6444
Loc: Licensed Electrical Contractor...
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In industry we use a contactor, heavy relay, to start our 240V motors. You would need one rated for the F.L.A. of your motor which is on the nameplate of the motor. The coil is wired with 110V being broken by the temp controller. The temp controller would act like a light switch and powers the contactor coil. You would need 110V for to the temp switch, black wire being broken by it and the white would go to the other coil connection. The 110V coil connections are normaly marked A1 & A2. The 240V would be broken by the contactor terminals generally using the outside 2 poles or sets. Hot wire from panel goes to the top of contactor and bottom of the contactor goes to the motor. There is normally a wiring diagram in the instructions.
Hope this is clear enough but if not then post back. Is hter a local JR college in your area? If so. a student of the industrial program could maybe show you how to wire it up.
I have seen 240V broken on only one side though such as in a heater but it is not the normal way or my preferred way to do it. The one leg broken will work and not harm the motor. On a 240V motor breaking one side will stop the motor but not hurt it. The one side broken has no complete path to return on, as a motor only uses 2 hot legs (no neutral or white wire). Just remember to turn off the breaker when working on anything with the temp controller or motor. But it is always imperative to turn off the breaker when working on anything electrical.
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Rule of thumb,Keep your thumb from under the hammer!
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bwk
newbie
Reged: 02/08/10
Posts: 4
Loc: Florida
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Thanks Guys,
OK, 3phase, I'm gonna proceed as originally planned. I thought that would work, but my son-in-law skeered me, so I thought I'd better check with someone more qualified than he and I.
Billy
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Gizmologist09
member
Reged: 02/08/09
Posts: 187
Loc: Palmdale, California USA
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*****CAUTION******
It would depend on the configuration of the switching circuit of the controller. if the LOAD contacts are relay controlled. no problem. If however they are controlled by a solid state system there may well be a problem including burning up the controller.
You need to get the info on the controller BEFORE hooking this up.
Edited by Gizmologist09 (02/08/10 01:55 PM)
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jdevlin
Carpal Tunnel
Reged: 09/09/02
Posts: 5959
Loc: Welland Ont. Canada
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Quote:
*****CAUTION******
It would depend on the configuration of the switching circuit of the controller. if the LOAD contacts are relay controlled. no problem. If however they are controlled by a solid state system there may well be a problem including burning up the controller.
You need to get the info on the controller BEFORE hooking this up.
Please explain how this can damage the controller by only switching one leg.
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Please do not PM with questions that can be answered in a Forum. I will not respond.
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bwk
newbie
Reged: 02/08/10
Posts: 4
Loc: Florida
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My thoughts exactly, jdevlin. I thought 110v was 110v. Well, aint it?
Anyway, y'all done skeered me again, so I went into the controller and Googled up a number that I found on one of the components. The number was FRL-264, which, THANK GOODNESS, turned out to be a relay.
So unless someone posts a stern warning that I'm about to burn up a 1/40 hp motor that operates on 220v by breaking one leg to act as an on/off switch, I'm gonna bravely forge forward! 
Many thanks Guys!
Billy
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Gizmologist09
member
Reged: 02/08/09
Posts: 187
Loc: Palmdale, California USA
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Some solid state switches are designed to handle a mximum voltage of 120volts. A 240 volt supply has 2 120 volt legs, true. HOWEVER, the open circuit voltage across the switch that controls only 1 leg is 240 volts. That is fine for a relay rated at 240 volts BUT a solid state switch not rated for 240 will fry. It can fry in either state on or off.
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