outlet on when thermostat on

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On 11/29/2010 2:37 PM, Sam Takoy wrote:

Easy, a line voltage thermostat can be obtained from many places.
http://preview.tinyurl.com/39ptkbz
If what you're wanting to do is interface with your HVAC system thermostat, it's a little more complicated. The simplest way could be an air switch, it's activated by air flow from the furnace blower.
http://preview.tinyurl.com/3xwnfoz
Using an air sail switch will keep the wiring for your auxiliary fan completely separate from the control system for your HVAC system.
TDD
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Easy to do by any electrician. You need a 24V relay, a box to house everything, a cord and plug, wires to the thermostat.
When the thermostat calls for heat, it sends 24 volts to the heater. You tag on to those wires and run a set to the relay. The relay is like a magnetic switch that closes the 120V contacts. You need to bring power in to the relay, then power out to a receptacle or proper cord that the fan is plugged into. All of this has to be assembled and mounted in a safe manner inside a box.
Parts would be about $40, about an hour labor charge for the electrician. There are also home hobbyists or maintenance guys at work that love to do this sort of thing too. Ask them about it.
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The only part of the thermostat that turns on the fan is the fan switch if he has one. Otherwise the thermostat calls for heat or cooling. When the fan gets turned on depends on what kind of forced air system he has. He was never clear on if he wanted the power on when the fan was on for both cooling and heating. Or even if he had both heating and cooling. A relay is probably the mst practical and code compliant solution. But if you didn't care about long term maintainability you could just run a piece of 14/2 from the fan in the furnace.
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On 11/30/2010 7:12 AM, jamesgangnc wrote:

One problem, most modern air handlers have an expensive circuit board which has a relay mounted on it to control the blower motor. If the OP somehow shorts it out, it will cost him dearly. Many of those circuit boards have an on-board fuse rated at 3 to 5 amps to protect the circuit board and the current draw from an extra fan may blow the fuse.
TDD
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Smitty Two wrote:

That looks like something I tried to build once, but then I ran out of hot glue and gave up.
Jon
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On Tue, 30 Nov 2010 08:01:44 -0800, "Jon Danniken"

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september.org:

I have a line voltage, 120 volts, thermostat in my poolroom. It is for heating only. Thermostat turns on a fan. Airflow thru an inline heater causes heat to come on only when fan is running. Anyway, what you need is called a line voltage thermostat. They are common and cheap.
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september.org:

I have a line voltage, 120 volts, thermostat in my poolroom. It is for heating only. Thermostat turns on a fan. Airflow thru an inline heater causes heat to come on only when fan is running. Anyway, what you need is called a line voltage thermostat. They are common and cheap.
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september.org:

I have a line voltage, 120 volts, thermostat in my poolroom. It is for heating only. Thermostat turns on a fan. Airflow thru an inline heater causes heat to come on only when fan is running. Anyway, what you need is called a line voltage thermostat. They are common and cheap.
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On 11/29/2010 2:37 PM, Sam Takoy wrote:

I put a 120V duct fan in one heating duct in my old house. I hooked it up to the furnace fan controller in parallel with furnace fan . When the furnace fan came on the duct fan came on.
LdB
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there is at least one gottcha with this plan if you have a multi-speed furnace blower.
The extra outlet will have 120V when the speed tap that you connect to is energized. But if your furnace at some time sets a different blower speed the exra outlet will have more or less then 120V.
If you wired the outlet to the low speed winding for example, you'll get 120V when the blower is runing low speed. But when the blower is running high speed you'll get more then 120 V which could be dangerous to your fan.
I think if you wire to the high speed winding, then the voltage will always be 120V or less which is probably safe. Moral of the story, check the voltage at your extra outlet at ALL the speeds that the blower might operate.
Mark
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On 11/30/2010 11:35 AM, Mark wrote:

The speed of a furnace blower with a conventional multi-winding AC motor is not controlled by the voltage. The speed is determined by which winding is energized. There are usually three speeds available via different taps. Low, medium and high with only two connected to the control board at one time. The speed for AC is usually higher than the speed for heating.
TDD
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On Tue, 30 Nov 2010 12:12:50 -0600, The Daring Dufas

transformer, perhaps? Never tried it, and I don't have a 2 speeder around to check with any more.
On my old furnace, though, the low speed was ALWAYS connected and powered - and the high speed just overtook it when powered up. Never had a problem in over 12 years running it that way (low speed never "open circuit"
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The Daring Dufas wrote:

If you connect the external fan to one of the motor speed leads and the furnace changes to a different fan speed, your connection won't be 120V.
If there is a DPDT fan relay and ordinary multispeed AC motor there is probably a point in the circuit that will work. Single speed motors are easier. I might hard-wire a duct fan, but for a receptacle I would use an isolating relay. Direct wiring a receptacle compromises the reliability of the furnace.
If you use a relay in a low voltage thermostat circuit, a different point is used for heating and cooling. If you tap the white wire for heating some thermostats may need to have the "heat anticipator" setting changed.
--
bud--

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Sam Takoy wrote:

Just tripped over this at home depot. Wonder if one could cut a hole in the plastic and adjust the thermostat? Or maybe it's not adjustable.
http://www.smarthome.com/manuals/7141_spec.pdf
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definitely going to be a non-adjustable unit. Likely a solid state chip switching a triac.
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snipped-for-privacy@snyder.on.ca wrote:

Don't know why I bother... If you'd read the link, you'd know it's not a triac.
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On 12/3/2010 3:42 AM, mike wrote:

I saw a reference to a bi-metallic switch UL listed for 100,000 cycles.
TDD
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electronic - just a simple bimet thermostat - but my "good luck" still holds - and any adjustment, if possible at all, would be "hit and miss". Lots of better solutions available.
The same supplier has the Duct-Stat http://www.smarthome.com/3018/DuctStat-Automatic-Duct-FanThermostat-DS100/p.aspx that will do EXACTLY what you want it to do, is adjustable out of the box, and can be used for either heat on or cold on applications.
And ONLY $25.00. It's only good for 5 amps, not 15,
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Find the blower contactor for yuor heater and get an apprpriately rated relay and wire the coil in paralell with the coil on the blower contactor. Wire normally open contacts in series with the outlet you want to control. I did pretty much the same with a helper fan. BTW Helper fan didnt work out very well, made the cold bedroom warm but made another warm bedroom cold.. Proper ducts and equalizing fixed the problem.
Jimmie
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