I bought a ceiling fan hoping there would be a schematic. The fan has a fwd/rev switch on it but it will be hanging 20ft in the air. I'd like to put a switch on the wall so I can reverse it without getting a ladder. I can't figure out how (especially without a schematic)?

But in the fan itself how do I go about bypassing the fwd/rev switch so I can use the DPDT on the wal instead?

What make/model is the fan? It can be done it requires 4 wires. It's really not necessary though, you can run it on forward all the time when your ceiling is that high and it will have the same effect.

It's basically a DPDT switch with the outer corners crossed. Leads are from the center and one end. It's wired like a DC polarity reversal switch is wired. Only 4 leads are required.
If you can put a DPDT relay in an accessible box, your there. I you can run 4 wires to a DPDT switch, your there too.

I bought a ceiling fan hoping there would be a schematic. The fan has a fwd/rev switch on it but it will be hanging 20ft in the air. I'd like to put a switch on the wall so I can reverse it without getting a ladder. I can't figure out how (especially without a schematic)?

But in the fan itself how do I go about bypassing the fwd/rev switch so I can use the DPDT on the wal instead?

If you remove the switch, there will be 4 wires attached to the switch. Take these 4 wires and run to a DPDT switch on the wall. The wall switch will have the ends crossed just like the original switch. If you really wanted to have a switch up there with a bypass, you would have to find one with a center off position. You really only have to remove two wires from the switch and that's the ones to the center terminals.

I gave you a second alternative as well. If you can mount an accessible junction box,like in an attic, you may only have to run two wires to a switch.

I know you won't rest until you get a schematic. Here is one, but may not be yours.

Raiku's World - Cheap Ceiling Fan Repair

And here is a more complicated one:

Ceiling Fand wiring Diagrams

4 wires are the way to do it as mentioned above. The crossing of wires on switch act like a polarity switch for DC Voltages. Takes 2 wires connected, Example: yellow to yellow, and orange to orange, then other switch position connects yellow to orange, and orange to yellow.
1 Last Idea comes to mind: A double pole/double throw relay in light housing, then you only need 1 more wire to fan(Off: relay deenergized/On: relay energized/fan reversed)
Don't have switch easily accessible. Someone will reverse while on high by accident.

That's excellent guys thanks a million

Wasn't until I was about to fall asleep. I remembered a 4 Way switch does the necessary switching, and has place for the 4 wires. It Swaps the wires, just like the Fan Reverse Switch.
Sorry Keepitsimple, didn't see your mention of polarity switch.

You could accomplish this also with 2 wires and a DPDT relay and a DPDT Switch... basically remove the switch and instead wire in the DPDT relay. Setup a switch in the remote spot. Your only complicated part will be the voltage for triggering the remote relay... you will need a transformer or a AC driven relay.

Another Thought, You could have the DPDT relay in switch housing, and an X-10 control
receiver module in canopy, then you could activate through existing electrical wires.
One problem may be no constant hot in canopy. Are you using speed and/or light control
for Fan?

Why a DPDT switch with a relay? It's not necessary. SPST switch would be fine because all you need to do is energize a coil.

Ideally, you should not be able to change the direction unless the fan is off, although a 15A or HP rated relay switch should handle it better than the 3A slide switch.

Thanks again to everyone, its always good to know you have options!

KISS,
I was saying a DPDT RELAY, cross the corners, then connect the 2 center wires on fan reverse switch, then the other 2 go to either of the ends(both need to be on same end)
Ideally you should turn off fan before switching, that is probably why the blades are in the way.
This situation where 20' is out of reach, I see the need for a direction switch. The remote switch Almost? Should have key switch with "DO NOT SWITCH WHILE FAN RUNNING"
I really don't recommend anyone doing this, I would do it.
I am just figuring ways to answer question.
Maybe a locking switch cover in out of the way area?

Strat:

I said the same thing long ago, maybe even in a different thread before he changed the subject. I looked at 4 fans and the blades are not in the way.

In reality, I think the switch, a puny 3A rated slide switch should not be moved while the fan is running, but a HP rated switch should have no problem. I think it's really a switch rating issue and not a motor issue.

I looked at 4 fans, no blades in the way of the fwd/rev switch.

Ok, all this is excellent, but unnecessary.

20' in the air you do NOT want a fan reversed, and for that matter you do not want a residential (reversible) fan. You want an industrial grade fan with three straight metal blades.

Industrial and commercial ceiling fans - Ceiling Fans N More