Electrical switch question

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Oh I get it now: power always on to thermostat switch, and _bypass_ the thermostat with the manual wall switch! Great. Thanks, Nate and thanks to all others too!!
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On 10/5/2011 1:47 PM, millinghill wrote:

Actually called SPST. SPDT is the same as a 3-way switch.

If the power goes to the fan first (power does not go to the switch then the fan) you can just change the wiring at the fan.
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Thats the way mine is.
Jimmie
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Correction No its not, I shouldnt post when half asleep. All you need is a two way switch connected across the tsat if you use the breaker for on/off.
Jimmie
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On Wed, 5 Oct 2011 08:01:41 -0700 (PDT), millinghill

Use 2 switches. One for On/Off and one for Manual/Automatic is the simplest way.
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for a single switch solution you could use a spdt like the Leviton 1285
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*You could use a combination device with one single pole switch and one three way switch. The single pole would serve as the on-off and the three way will change it from thermostat to always on.
http://www.legrand.us/passandseymour/switches/combination-devices/standard/switches/696wg.aspx
I think this combination is also available in Decora style. Go to an electrical supply company to get one.
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On Wed, 5 Oct 2011 18:15:11 -0400, "John Grabowski"

3 way not required. Sw 1 powers the thermostat through the black wire. Switch 2 powers the fan (fan side of 'stat" through the red wire, from the black wire at the switch. Sw1 on means the fan is on thermo, Sw1 AND Sw1 on means fan on direct. Sw2 only on, fan is off
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On Oct 5, 11:50pm, snipped-for-privacy@snyder.on.ca wrote:

Inquiring minds want to know..... Why does the OP want to run the attic fan without the attic being hot? Mine is wired with a switch in series with a thermostat on the fan, just like his is now. Works fine for me. Some places it's desirable to have them run for dehumidification, but for that you wire in a control that measures temp and humidity.
If he does want the option of running it when it's not hot, then the SPDT switch is the way to go. It's simple and won't look like a hack job, which is what he'll have with two switched, sided by side.
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On Thu, 6 Oct 2011 04:39:49 -0700 (PDT), " snipped-for-privacy@optonline.net"

Personally, I don't like it when I have no override for things like this.

Yes, those space capsules with 50 switches side by side really look lke hack jobs.
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Good question. I am ~considering~ running the attic fan without the attic being hot due to a COMPLETELY different subject and thread: (Amazon.com product link shortened) which suggests via this report by the Army Corps: http://www.crrel.usace.army.mil/library/booksnongovernment/MP02-5778.pdf that after you insulate your attic, seal air leaks from conditioned space below, and install passive ventillation as much as practical, you may still get an ice dam in the winter simply due to large amount of snow acting as its own self-insulating blanket (happened to me and many neighbors last year) and that instead of installing heat wires etc. on the shingles, the next reasonalbe solution would be to power ventillate the attic to make sure that the temp stays BELOW freezing during the time that environmental conditions are favorable for ice dams to occur (per report).
Like I said, completely different thread and I don't want to hijack this one. I respectfully suggest we start new thread if folks want to comment on this aspect. -OP
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Ya know, if you don't have at least one square foot vent opening for 300 square feet of vented space, you have no warranty on most shingles, such as Certainteed and Owens-Corning. Verify warranty details at 1-800-ROOFING. But putting that aside, the main aim is to get any BTU's that make it up to the attic to be removed. Problem with your plan is that a roof fan will also pull conditioned air from within the wall spaces, causing a net loss in your efforts to keep warm in, cold out. Also, I've gotten damn tired of dealing with sites with damage caused by an overheated fan. A lot is depending on an overtemp sensor supplied by the lowest bidder in China. Those fans get forgotten about, at the hottest part of the roof, and all the worst if you turn on the fan and then forget it. Better to put a timer switch to shunt the t'stat if you feel you really must. It would be nice to have a remote-reading temperature sensor in the eaves area, displayed near the timer switch.
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On Thu, 6 Oct 2011 04:39:49 -0700 (PDT), " snipped-for-privacy@optonline.net"

A center off SPDT switch can not be had in a "wall switch" configuration that looks like a normal house switch so IT will look like a hack. A double gang switch is an everyday situation -even triple gang switches are very common. In fact you can buy 2 witches together in one unit that fit a single box and use a duplex receptacle plate.
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On Thu, 06 Oct 2011 19:45:32 -0400, snipped-for-privacy@snyder.on.ca wrote:

I posted a link a couple days ago for one in Decora.
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You will need a Center OFF switch. Hot wire from the panel goes to common connection on the switch, other two wires dont matter which but one goes to the normal connection and the other connects to a point that bypasses the T stat. Mine was wired directly to the breaker panel, no switch. What I did was wire the switch across the T stat and I located this switch by the attic entrance so I can turn the fans on full when I go up there. Switch only selects normal operation or Bypassed Tsat operation ...OFF/ON is done at the breaker panel.
Jimmie
Jimmie
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