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-   -   Fan / limiter switch replacement (http://www.diychatroom.com/f17/fan-limiter-switch-replacement-140546/)

Cysnake 04-17-2012 11:26 AM

Fan / limiter switch replacement
 
What a wealth of knowlege on this site! :thumbsup: I was hoping someone could give me a little advice. I have an old GE oil furnace model 21 that I have been pampering every year until i can afford to replace the system.
http://i78.photobucket.com/albums/j1...e/furnace1.jpg

http://i78.photobucket.com/albums/j1...rnaceident.jpg



The fan/limiter switch has pretty much fallen apart, losing the plastic adjustment dial in the center. Now my blower fan is running constantly.




http://i78.photobucket.com/albums/j1...e/limiter1.jpg

http://i78.photobucket.com/albums/j1...e/limiter2.jpg


http://i78.photobucket.com/albums/j1...e/limiter3.jpg




Obviously due to the age of the furnace, i wont find exact replacement parts. I was looking at replacing it with a honeywell L4064B2228.
http://images.drillspot.com/pimages/9119/911961_600.jpg





http://www.drillspot.com/products/51..._limit_control

But im not sure about it. Can somebody let me know if the honeywell would work, and where to connect the wires, and what i should adjust it to when its installed? My system only has 3 wires, the black wire is jumped across both the fan and the limiter switch, red goes to the fan, and yellow to the limiter. If the honeywell wont work, is there a cross reference for one that would?

Thank You all for any help!

Chris

REP 04-17-2012 11:47 AM

That is what GE (Trane) would have given you 30 years ago when they stopped making that unique F&L control.
The Honeywell will be the opposite I.E. the black wire will go on the bottom.I'm not sure about the red and yellow wire.I think the red is fan and the yellow is limit but I am not certain its been a long time.Just follow the wiring diagram on the furnace pannel and it will show you what is what.

ben's plumbing 04-17-2012 08:05 PM

Quote:

Originally Posted by Cysnake (Post 900892)
What a wealth of knowlege on this site! :thumbsup: I was hoping someone could give me a little advice. I have an old GE oil furnace model 21 that I have been pampering every year until i can afford to replace the system.
http://i78.photobucket.com/albums/j1...e/furnace1.jpg

http://i78.photobucket.com/albums/j1...rnaceident.jpg



The fan/limiter switch has pretty much fallen apart, losing the plastic adjustment dial in the center. Now my blower fan is running constantly.




http://i78.photobucket.com/albums/j1...e/limiter1.jpg

http://i78.photobucket.com/albums/j1...e/limiter2.jpg


http://i78.photobucket.com/albums/j1...e/limiter3.jpg




Obviously due to the age of the furnace, i wont find exact replacement parts. I was looking at replacing it with a honeywell L4064B2228.
http://images.drillspot.com/pimages/9119/911961_600.jpg





http://www.drillspot.com/products/51..._limit_control

But im not sure about it. Can somebody let me know if the honeywell would work, and where to connect the wires, and what i should adjust it to when its installed? My system only has 3 wires, the black wire is jumped across both the fan and the limiter switch, red goes to the fan, and yellow to the limiter. If the honeywell wont work, is there a cross reference for one that would?

Thank You all for any help!

Chris

yes it should work... wiring changes I think not sure just look at diagram with unit it will tell you..:yes::yes:

how 04-17-2012 08:21 PM

Your black wire on your old control is the power supply for new honeywell fan/limit control. The color coding for your fan & limit controls suprises me. If you are sure which is which then the honey well control is marked with fan & limit for the two connections furthest from where the lines enter the control.. Leave the breakable jumper in place.
If you are not absolutely sure which is the fan line and which is the limit line .......Follow your red & yellow line from your old fan/limit control to the next junction box that the jacketed cable goes to. The limit will go to the burner or to power the transformer while the fan line will go to the blower.

Cysnake 04-17-2012 08:57 PM

Thanks everyone! I wouldve thought the reverse for the black wire. I was 99% sure that wouldve been the ground because it was connected to both. Ive torn this furnace apart and rebuilt it so many times, but this is the first time ive hhad to deal witth the switch. Hopefully i can be of some assistance to you all in the future! The red wire should be the fan, atleast thats what it says on the microswitch its.connected to and same for the yellow. Thanks Again!
Chris

how 04-17-2012 10:43 PM

Yeah, it's connected to both as a common power source for both switches. The new honeywell control uses the same set up except it uses a small built in brass jumper to connect both controls.

Cysnake 04-17-2012 11:53 PM

Ok, one more small snag. Just measured and i have a 3" insertion limit. Can anyone recommend a different switch? The one i was looking at is a 5" insertion.

how 04-18-2012 12:20 AM

Is it a 5" vent pipe? If so, perhaps a couple of washers around the probe will allow the honeywell control to work.

REP 04-18-2012 01:08 AM

If you indeed hit the heat exchanger with that 5" incertion at the spot the old F&L was located,you will have to relocate it in the plenum as close to the heat exchanger as possible.It won't look pretty but it will work and it is what GE told people to do in exactly your situation.

Cysnake 04-18-2012 01:00 PM

In my first pic of the furnace i just realized that coming off the pipe in the front is another fan limiter switch that is not connected, is this an acceptable place to mount a new switch, or could i drill through the plate in the back of the old switch hole to accomodate for a 5" insertion instead of a 3"?

REP 04-18-2012 01:29 PM

That relay is not a fan limiter switch,it is a pyrostat which is a safty switch for the burner.
If when you try to incert the 5" probe ,you hit the heat exchanger,you cannot use the F&L in that spot.
If you were to try to drill in that spot you would damage the heat exchanger.
See my above reply to see where to put that honeywell F&L if you can't put it where the old one was.

beenthere 04-18-2012 05:55 PM

Check into a camstat fan limit switch. they have 3" inserts.

Cysnake 04-19-2012 08:40 AM

Ill check into the camstats. Thanks Again!

hvac5646 04-19-2012 04:22 PM

Quote:

Originally Posted by beenthere (Post 901916)
Check into a camstat fan limit switch. they have 3" inserts.

Not rated to be in oil flue path.

beenthere 04-19-2012 04:58 PM

Quote:

Originally Posted by hvac5646 (Post 902518)
Not rated to be in oil flue path.

he's talking about the old fan limit, not the old stack control he also has. Which looks to have already been disconnected when the put a new burner in.


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