Marley/ Fahrenheat FUH54 Thermostat Switch heater wiring - help?

Good morning all,

I have my Fahrenheat FUH54 wired up according to the following posts that I found:

Coloradotrail rider: http://www.garagejournal.com/forum/showpost.php?p=2517843&postcount=48 in the thread Installation of Dayton G73 Heater with Cutoff Switch and Thermostat"

bottomfeeder's post http://www.garagejournal.com/forum/showpost.php?p=3371669&postcount=6


and this site: http://www.watsondiy.com/heater.htm



When i have the heater directly wired up, without the switch it works fine. But when i put the switch in and route the wiring as shown in the posts above, it doesn't work. This is where i am stuck.

- With Switch on and thermostat off the line from the switch to the thermostat is correctly at 0 volts.

- With the switch off and the thermostat on, all lines show 120 volts, even on the switched side of the switch.

It is kind of hard to explain, but i have tried a bunch of different wiring combinations, and even with both the switch and thermostat on, the heater won't turn on. My switch is a 30 amp double pole switch that i am using one side of.

I have battled this thing through a few hours of trying different combinations, but i still can't seem to get it to work right. I'm ready to just to give up and climb up on the ladder each time i want to turn it off so it can still cool down.

Any ideas? I can provide more details if needed.

Thanks!

On Bottomfeeders post I do not see how he integrated the white conductor from his unit's main power supply cable, in to a wall thermostat or switch...of which I cannot find in his pics. Not really kosher wiring practices, to use the neutral conductor as stated.... but whatever works for the owner I guess.

Thanks Greg. It is 240V, so there isn't a neutral line. I used the same wire i used for L1 and L2 since I ran EMT.

Just going by what your op stated when you said you wired it according to BF's post and others. And BF used the neutral conductor of his main power cord to go somewhere for his remote control.....

I looked at the only manual for the FUH 54 on line that I could find. The manual does not have a "remote" thermostat option. Can you show of pic of the unit's actual wiring diagram as they will be the most accurate. .

Greg, see below. The others that i quoted in the OP put the switch in between the leg from the L1 to the thermostat.

Thanks,
Brandon

gregtwojeeps said:

... Can you show of pic of the unit's actual wiring diagram as they will be the most accurate. .

Click to expand...

This, get us a picture of the (original) wiring diagram. Probably on the back cover.

Thanks. It is attached to the post above yours.

Bethomas,

To turn the built-in thermostat on/off from a wall switch, I simply interrupted the power feed to the thermostat:



When wired in this manner, if the wall switch is "on" the heater functions as if nothing has changed. If the wall switch is "off" no electricity flows to the thermostat, and the heater "thinks" that the room is up to temperature and the heating element shuts off. Since we aren't interrupting power anywhere else, the fan will continue to blow until the heating element cools down.

I didn't cut any wires. I simply disconnected the thermostat wire from the L1 connection and swung it over to one side of the unused "A" connector on the "wattage change terminal board". I then connected one 10 gauge wire from the wall switch to the other side of the "A" connector, and the second 10 gauge wire from the wall switch to the L1 connector (where the thermostat wire used to be).

One thing to keep in mind is that we are only manipulating the thermostat. Turning the wall switch off DOES NOT turn off the power to the heater!! I put a note inside the access panel of the heater warning of this, and included instructions on how to restore the heater wiring to the original configuration in the event that someone in the future besides me is messing around in there.

Hope this helps.

Thanks! I'll give that a shot. I think I see where I went wrong, but I just copied the wiring from the Watson diy page. Could it be because I'm only using one side of a double pole switch? I don't think it should matter though. Same goes for pulling the power either from L1 or further upstream.

Thanks again!

bethomas, did you figure this out? I'm in the exact same situation, using the same links as you. I'm wondering if the newer thermostat (black wires) is playing a factor.

For anyone looking for an answer through endless internet searches, I finally found my issue. The wiring schematic in the first post is accurate, but make sure that your hot wire on the switch is the same wire connected to L1 in the terminal block on the heater. I am using a 4 cord dryer plug and foolishly assumed the black wire from the cord was the same as the black wire I had connected to the switch, when in fact I had the hot wires swapped. Once I swapped the x and y connections on the dryer outlet, I was good to go! Hope this helps save someone the hours I spent spinning my wheels...

Fahrenheat FUH54 Thermostat Switch heater wiring - help?

Bottom Feeder -I received a Fahrenheat FUH54 for Christmas for my garage. I was reading your post on how to wire a switch to control the thermostat and just wanted to get your go ahead on how I interpreted your description, see attached . I have an extra 2 pole 30 amp switch laying around and wonder if I could use it by just wiring one side. Thanks your idea and help - Mike