[zekenator]

Hi all, this is my first post. Thanks in advance for any stupid questions or things said by me as I am self-taught in electrical stuff.

I wired my whole 1 car garage when I built it into my fab shop. Had 220 service put in, then by reading and learning both online and in books I did the whole thing myself with 6 circuits, 1 50 amp for my welder, 1 30 amp for my electric heater, and 4 20 amp circuits for outlets all around the garage.

That said, I consider myself a complete rookie noob, so bear with me please.

I have a Fahrenheat FUH724 7500w electric forced air heater I need to install since my little electric one died and I had this one lying around for free for 3 yrs and didn't realize how good it was. (I am changing the 30 amp circuit to another 50 amp circuit for this new heater.)

I found this video on YouTube (link to follow) which (kinda) describes the install of this exact heater *AND* a remote thermostat, the Dayton 2E815 line voltage thermostat, and it looks like it works awesome. This is what I want, and I bought the exact same thermostat but can't figure out how to wire it up when I remove the stock stat from the heater.

There are only 2 wires coming from the stock stat, one goes to the power block at L1, and the other wire goes to L3 - 2 on the contactor. The remote stat has three wires: red, black, and blue. ?????

The YouTube vid poster responded to a couple of my questions, and said he only used 2 of the wires and was supposed to get back to me on what went where, but has not after repeated attempts from me.

So, can someone please explain

1) how this works, and more importantly,
2) how do I wire up the remote thermostat?

Pics attached of everything I think is needed to know. Thanks so much everyone.

-Brian Z aka zekenator

 

[zekenator]

It won't let me post a link even though I have 1 post now, so the title of the YouTube video I referenced is "Fahrenheat FUH724 (FUH54 Big Brother) Garage/Shop Heater Install Demo".

Here's one last pic of the power block in the heater.

Thanks everyone, am looking forward to the responses to this and to learning a ton more. :glasses::biggrin2:

-Brian Z aka zekenator

 

[RAL238]

Are you sure you have a 2E815 thermostat and not a 2E816? The blue wire sounds like it is the 2E816, which supports cooling as well as heating. If that's what you have, just cap off the blue wire and connect the black and red wires to the heater.

 

[surferdude2]

<deleted.
*
I line voltage thermostat rated for 40 amps would be the way to go. Then you can leave all the heater wiring intact and just hook the stat in the line feed. It will be code compliant that way.

The stat you have isn't rated high enough. I'm not sure you'll find one rated for 40 amps so you may need to install a 24 volt coil contactor at the feed point with a small step down transformer in it for 240-24 vac to make the stat wiring low voltage. That would still be code approved.

 

[Oldmaster]

Looking at the schematic the thermostat controls the contactor. Your thermostat will work, the coil has very low current.

 

[Oldmaster]

Save yourself some money and buy a single pole wall stat. That's all you need. Cost about $20.00.

 

[surferdude2]

Save yourself some money and buy a single pole wall stat. That's all you need. Cost about $20.00.

He already has a low amperage stat. That isn't the issue.

My concern is that when you exit the approved fixture with that small thermostat wire, you are in violation of code and creating a personal safety hazard as well. The 50 amp breaker for this device may surprise you when you short it on a length of #12. Moreover, when you make those changes internally to the heater and run its wiring outside the fixture, you have violated its UL rating.

I wouldn't recommend doing anything that risky to someone I don't know. I wouldn't even do it myself.

 

[Oldmaster]

Who said anything about low voltage t-stat wire? The present t-stat is 120 volt controlling the coil.It is intrinsically safe. Has nothing to do with the heater amps or anything else. Use an approved wiring method and extend the remote. It does not interfere with the listing. Non issue.

 

[surferdude2]

If it were mine, I'd probably change out the contactor for a 24 volt coil version and install a a small 240-24 step down transformer in there where there was room. Then I could run low voltage stat wire out to the wall stat without conduit. That's just me though.

It still violates the UL rating but for my use I see no hazard. Others may have different standards.

 

[Oldmaster]

Why? No logical reason to do this. If your dead set on low voltage change the coil on the existing contactor. Add a contactor and transformer and throw a perfectly good contactor out. Makes no sense to me.

 

[zekenator]

Are you sure you have a 2E815 thermostat and not a 2E816? The blue wire sounds like it is the 2E816, which supports cooling as well as heating. If that's what you have, just cap off the blue wire and connect the black and red wires to the heater.

OOPS...duh...fat finger there, yes you are correct I have the 2E816.

Wow ok, yeah that makes total sense given what I've read and seen.
It sounds like it doesn't matter if the black or the red wire go to the power block, that it's just all one circuit then...is that right?

 

[surferdude2]

Who said anything about low voltage t-stat wire? The present t-stat is 120 volt controlling the coil.It is intrinsically safe. Has nothing to do with the heater amps or anything else. Use an approved wiring method and extend the remote. It does not interfere with the listing. Non issue.

The present coil is 240 volts. There is no neutral in there, not that it matters as far as the ampacity of the feeders. He will have to change the coil or get a DP relay if he elects to go the class 2 way.

There is nothing intrinsically safe about running smaller wire outside of the fixture that would be protected by a 50 amp breaker.

The money for the DP contactor would be offset by not having to run conduit to the stat.

I didn't say low voltage stat wire unless he decided to do it the way I suggested with the transformer.

If he doesn't convert it to class 2 control wiring, any wire outside that heater would need to be sized to be protected to the circuit ampacity of the feed just for worse case failure when 50 amps could flow.

I know of no code installation where a branch circuit breaker of 50 amps is sub fed to a thermostat with smaller wire than the feed to the fixture.

 

[Oldmaster]

This is my last post concerning this. I have a 100 hp motor in the mill and the starter is controlled by a start/stop station fed by #16 wire. There is no protection on the control circuit because the coil wires will melt long before anything else could happen. It's done all the time and is NEC compliant. Have no desire to debate with you.

 

[surferdude2]

I'd spend the small price and do it the safest way possible. You'll save time and money by not having to run conduit to the thermostat and can move it easily if the location doesn't prove satisfactory. The wire can be 18/2 jacketed thermostat wire which can be run without conduit on a class 2 system.

You could change the coil in the existing contactor but it may cost less to just replace it.
Contactor

Transformer

 

[betelgeuse]

This is my last post concerning this. I have a 100 hp motor in the mill and the starter is controlled by a start/stop station fed by #16 wire. There is no protection on the control circuit because the coil wires will melt long before anything else could happen. It's done all the time and is NEC compliant. Have no desire to debate with you.

The maximum motor current for control wires is on Table 430.72(B)
#16 is listed at 40Amps, with wires enclosed by the controller.
It doesn't even qualify if it is remote to the controller.
Even @ 480V 3 Phase a 100HP draws 124 Amps according to the NEC.
It's not compliant at all.

 

[Missouri Bound]

I have a similar heater except it is 17,500 watt.
I installed a line voltage thermostat, in conduit to break the thermostat circuit.
I do not know the current draw of the thermostat circuit but I already had one to use, so I used it.
What I did is cut the heater mounted thermostat wires and connect them to the line voltage stat, taking the heater mounted stat completely out of the circuit.

This allows the fan delay to work as designed when either the thermostat is satisfied or the thermostat is shut off.

 

[surferdude2]

Yeah, that's how I'd do one if it was for me. Even at the most liberal interpretation of the code, you'd need #12 wire for the stat run considering you have the heater on a 50 amp breaker. I think even then a competent inspector will shoot it down.

I've been through similar circumstances before and had inspectors tell me it's not allowed to use downsized tap conductors from a branch circuit. I found nothing in the code to prove them wrong.

I would never advise anyone to do that on a forum since they don't have a high level of skill in the area they are inquiring about. This stuff lives on forever and I try to keep safety first right up front. For example, what if someone ran #14 romex for that thermostat because they saw the other romex in their garage was that size. See what I mean? It's hard to cover all the bases so I go the safest way up front.

As for you @Missouri Bound, I feel sure you didn't run 14 ga. romex on your thermostat... did you? :smile:

 

[Missouri Bound]

As for you @Missouri Bound, I feel sure you didn't run 14 ga. romex on your thermostat... did you? :smile:

I installed this in my workshop last year. All of the wiring for the shop is 12 ga
I will add that the thermostat wires in the heater were 14 ga. :devil3:

 

[surferdude2]

Manufacturers can get away with a lot since they get UL approval to violate the NEC and it will be acceptable anywhere without question.

In your case @Missouri Bound, you won't like to hear this but you have an 80 amp breaker serving that heater. Even if you use the motor controller tables at NEC 430.72(B) you should use 10 ga. copper for the remote wires at your power level.

I'm not suggesting that the motor controller table is appropriate for this heater or any similar device but that's the only place I can see in the code book that allows downsizing the tap conductors to serve remote switching devices. I'm not even suggesting that you change your installation... just putting the info out there for critical review. Let your conscience be your guide. :wink2:

 

[Missouri Bound]

I guess I didn't explain that as well as I should have.
The receptacles are all 12 ga.
The heater is wired with 10 ga.wire.
Farenheat specified a dbl. pole 30 amp breaker, which is installed.

The heater circuit is contractor switched, as you may have expected.
The onboard thermostat switches the contactor. (if you use one)
The fan control is not connected to the contactor.
The thermostat is a single pole which controls the 240v circuit to the fan and the contactor.
The fan switch is delay on start and stop.
The thermostat (control) circuit has an approximate amperage draw of less than .5 amp. I cannot find the specs on the contactor coil so that is an educated guess, probably on the high side.
My clamp ammeter won't register that small amount.
Sorry for any mis-understanding.