I picked up the Master Flow attic fan thermostat today at Home Depo.

First question: What temp are you setting your fan thermo on?

NEXT Question: Can I leave the cover off of it ?

Lastly, please read below: AM I MISSING SOMETHING? AM
I RIGHT THAT THE FANS WILL NOT START UP UNTIL ENOUGH
HEAT IS GENERATED?

OBSERVATIONS:

Did a wire layout and test, WORKS ! shuts down, starts up, ect
like it should.... anyway, I did some tests, used a ceramic heater
to set it off, ect and I noticed............

This thing takes awhile to register the temp changes... especially
with the cover on it..... I am thinking of leaving the cover off.... set
my desired temp, and leave the cover off.... for example, I
had the ceramic heater blowing on it about 3" away and It took
what seemed too long to catch on and start up the fans.... likewise,
I took the heat source away, and it ran and ran, then I blew cold air into
one of the holes on the cover and it shut down.......

Dont get me wrong, Im going to use it, just wondering if I could
leave the cover off, so it reacts quicker to temps on the way
up as well as on the way down....

It seemed to me that the time it took to heat up inside that cover
and start up might be enough time for the LCD to get damaged,
or a frez to get bent.

I have mine set at 90degrees. It turns on after about 4-5 minutes. The Lcd has never gotten above 88 degrees before the fans turned on.

And the fans stay running about 6-7 minutes after the projector is turned off. And I've left the cover off with no problems.

uhhh, so 1) you DO leave your cover off (the cover of the thermo module) ?
this is what I think I should do, just didnt know if it was common practice.

Actually I just leave mine on. It looks more professional.

You wrote:


Sounds like you're not following the recommended wiring. Be sure to check the "Reference and Tutorials Forum". There are plenty of good schematics.

The fans should come on when you first throw the switch for the lamp. If you use the DPST (dual pole, single throw) switch, the power in that comes from the bottom (or line in) side also attaches to the thermostat. The top of the switch (or load side) goes to the fans.

When the PJ is first turned on and the temperature is "cold", the fans are powered from the load side of the switch. The box heats up and the thermostat switch closes also supplying power to the fans. When the switch is turned off to cut power to the lamp, the thermostat switch is still closed and the fans run until the temperature lowers to your setting. I use just under 80F for the cutoff.

Yep, Now Im going to have to re-eval. Thanks. here is how I am doing it.

1) power enters box thru dpst, then on the hot terminals (those that are not affected by the switch being on or off, ie, always hot as long as it is plugged into outlett......... on the LIVE, I have it going into the thermo, then back to the fans....... then, the fan negatives are wired right into the negative of the dpst, same with the ground........PLEASE TELL ME WHAT TO DO DIFFRENT !!! Thanks a bunch - stiltskin

Sounds like others are doing it this way.


What I am stumbling on is how to have these fans start up right away when the whole unit is turned on, yet they remain on when the pj is off, waiting on the ok to shut down from the thermo........How do I do this? I want to do it right (as best as possible)

Thanks.

There is NO "negative" on the DPST switch! (I'm assuming you're in the US using 110v) There are 4 terminals on each "corner" of the switch. The bottom terminals (switch lever in off position facing down) are the LINE IN terminals. The power wire from your power cord (usually black) is connected to both sides on the bottom. One side, say Left, is power for the ballast; the Right side is power for the fan(s). Your power cord should be 2 conductor, 12 ga. with ground. I use a cord from a power strip since it has a 3-prong plug with heavy sheathing that prevents splits.

The two terminals at the top of the switch are the LOAD sides. Following our example, the Left side should have the ballast power wire. On the Right side of the DPST switch at the top is the power to the fan(s). One wire from each fan should be connected to this switched side. The other wires from each fan should be connected to the common/neutral wire.

When you flip the switch, power feeds to the fans (right side) and to the ballast (left side). The circuits are independent of each other (dual pole), but activited with one motion (single throw).

Now the attic thermostat switch. Connect one of the two thermostat wires to the "fan" Line In side of the switch (in this example the BOTTOM, right). Then connect the other wire from the thermostat to the power in wires of the fans. When you PJ power cord is plugged in, there is always power to one side of the attic thermostat. If the temperature goes above the set amount, the circuit will close and the fans will run. So set the thermostat a few degrees above the expected room temperature.

All "negative" wires are connected together and never to the DPST switch. The switch body will have a metallic green grounding screw and this should be connected to your ground wire in the power cord (usually a bare copper wire).

Edited by stiltskin

the thermostat is connected across the fan switch, one side to power, one side to fan. when you turn on the power the fan should start right up, after you shut off the power the fan thermo will stay on untill it cools to shut down. I have mine set at 90 degrees. it opens at 80 degrees for shut off. I left it in its case.