elevator damper/fan wiring

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It works but I would bypass the T-stat and wire directly to the fan just in case you have a problem with the stat you would still have fan operation in alarm mode.
 
R Bob said:
As it stands now the T-stat will control the fan no matter what the power source is.
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Cold Fusion said:
Nope. It will work exactly as your description of operation.


When the FA relay pulls in, the t-stat relay drops out. Fan is on.

cf
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Wasn't trying to say it wouldn't work.

Just trying to point out to Rewire, that there is power present @the NO terminal of the fan relay in normal mode, and there is also power applied to NC terminal of the fan relay in alarm mode.

In alarm mode, the C terminal of the fan relay will be energized no matter what position the T-stat contacts are in, thus running the fan.

After reviewing my post, I must say that I used an extremely poor choice of words to convey my point.

Made sense to me @the time! :)
 
Rewire said:
It works but I would bypass the T-stat and wire directly to the fan just in case you have a problem with the stat you would still have fan operation in alarm mode.
Click to expand...

Probably a hundred ways to do this - some good some not so good. I'll bet the OP would like to see a sketch of your proposed wiring - I know I would. Sometimes its hard to envision from a verbal description.

cf
 
R Bob said:
Wasn't trying to say it wouldn't work. ---

After reviewing my post, I must say that I used an extremely poor choice of words to convey my point.

Made sense to me @the time! :)
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(emphasis is mine - cf)

I don't know what to say - that never happens to me:roll: (or does regularly ;))

cf
 
Rewire said:
It works but I would bypass the T-stat and wire directly to the fan just in case you have a problem with the stat you would still have fan operation in alarm mode.
Click to expand...

the way i wired it, you dont even need a t stat for that fan to work in alarm mode. do you see the 2 pole relay? when the fire alarm kicks on, the 2 pole relay closes and sends power directly from the UPS to the fan. the t stat doesnt do a thing in alarm mode except sit there.

i wired it and tested it and it worked great.

i am sure the elevator company spoke with the hvac guys to come up with a plan about this. the wiring needs to be done by a licensed electrician. the hvac guy explained what he wants to do and bought all the relays i needed. he pretty much left the wiring to me.

it seems the laws in the city seemed to be more relaxed than the laws in the real big cities. these relays are UL listed for smoke alarm installations too.
 
electricalperson said:
the FA relay coil will only be powered up during alarm condition with 24v from the FACP. when that relay is powered up it cuts power to the damper and sends power directly to the fan. the way its wired that fan will get turned on during a fire no matter what. if that thermostat wants the fan on the fan will turn on. if theres a fire alarm when that fan is already on, when the thermostat is satisfied that fan will still remain on because the FA relay will be switched from normally closed to normally open cutting power to the damper and sending power to the normally closed terminal of the other relay turning that fan on
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to further muddy the waters......(the FA relay coil will only be powered up during alarm condition with 24v from the FACP)......Don't forget to monitor the 24v for power loss
 
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