5000w heater and smart tstat wiring

TBL194

I am pulling my hair out here as I can't figure out this wiring. I have done this before on a different model heater so it does work. I have this https://www.amazon.com/Aube-RC840T-240-Switching-Electric-Transformer/dp/B0037MXM1C?th=1 and this https://www.farmandfleet.com/products/1473058-beyond-heat-5000-watt-garage-heater.html. I get as far as the tstat lighting up but it will not control the heater. Here is the internals of the heater. I have read and black from aube to l1 and l2 but blue idk where to go. Whoever can get this to work gets $20 via venmo

HVACNUT

$20? Maybe I'll go to the movies... by myself. (Credit: "Trading Places").
I can't except money. Community service is part of my sentence. 

Can't see all the ratings on the relay.Does that say 1.2 VA? If so you'll need a separate transformer and isolation relay. 

pedmec

your blue and black are your 240 volt feed to the internal trans former and the red is getting switched. the red is feeding power to whatever your trying to control. post wiring of water heater electrical.

ratio

How 'bout a schematic of the heater (should be on a sticker inside the cover), & a clear view of the face of the Aube relay? I'm guessing that this relay isn't the one you need, but I can't be sure. 5 kw at 240 volts is over 20 amps, that's over the tip top range of the more common relays—but the heater might be set up in a way that the relay doesn't need to switch the full current of the heater.

pecmsg

ratio said:

How 'bout a schematic of the heater (should be on a sticker inside the cover), & a clear view of the face of the Aube relay? I'm guessing that this relay isn't the one you need, but I can't be sure. 5 kw at 240 volts is over 20 amps, that's over the tip top range of the more common relays—but the heater might be set up in a way that the relay doesn't need to switch the full current of the heater.

Heres the relay
https://www.amazon.com/Aube-RC840T-240-Switching-Electric-Transformer/dp/B0037MXM1C?th=1

TBL194

I will get a schematic and I used this relay for a previous 5000 watt unit and worked great. Appreciate the responses and will post shortly. 

109A_5

Hello @TBL194,
Get the colors lined up and it should make more sense.
EDIT: Example #1
If you want your external thermostat to control the whole unit including that internal thermostat controller board, with no cutting of the heater's factory crimp connectors.
Then;
Make the building wire Black connected to the Aube-RC840T-240 Black, only (wire nut).
Make the building wire White L2 on the connection terminal block.
Make the Aube-RC840T-240 Blue connected to L2 on the connection terminal block.

Make the Red of the Aube-RC840T-240 connected to the L1 on the connection terminal block.
The Aube-RC840T-240 has the power it needs and powers the external thermostat.
Done.



EDIT: Example #2
If you want the heater control board and thermostat on all the time (and do what they do) and you just want your external thermostat and Aube-RC840T-240 relay to control the heating element only.

Make the building wire Black L1 on the connection terminal block.
Make the Aube-RC840T-240 Black L1 on the connection terminal block.

Make the building wire White L2 on the connection terminal block.
Make the Aube-RC840T-240 Blue L2 on the connection terminal Block.

Remove the Heavy Red wire from L2 on the terminal block and connect it to the Red wire of the Aube-RC840T-240.
Remove the Heavy Black wire to heating element from L1 on the terminal block and connect it to the Red wire of the Aube-RC840T-240.

The Aube-RC840T-240 Black and Blue always need 240 VAC to power your external thermostat and the relay. The Aube-RC840T-240 Red is switched Black.

Having the Aube-RC840T-240 Red to the heater's L1 is useless.

TBL194

@109A_5 So just so I understand, the first one will work the heater and fan so basically the tstat just turns it on and off? Send second work just works the coil and not the fan?

I did both examples, both make turn the tstat on but neither one turns the heater on?

109A_5

Hello @TBL194,
The first example the power to whole heater unit is controlled by the external thermostat, all on or all off.

The second example (what I was going for) just the heavy wire to the heating element is interrupted. So maybe in this case the fan may continue to run.

If you need some pre or post fan run time, something else may need to be done.

Since it looks like it has its own internal thermostat the best way to me would be to have the Aube-RC840T-240 interrupt that thermostatic switch (if possible), which may be more complicated to wire.

TBL194

@109A_5   I wouldn't mind just a simple on/off with the tstat due to the heater hanging from the ceiling. Any ideas? 

TBL194

I had a unit like this and wired it and it worked.  Same rotary tstat on the unit. 

109A_5

Hello @TBL194,

TBL194 said:

@109A_5   I wouldn't mind just a simple on/off with the tstat due to the heater hanging from the ceiling. Any ideas? 

My first example with the wiring diagram would do basically that, you would just have to preset the controls.

This image is of a simpler unit, no electronics, and if you look closely it looks possibly like the internal thermostat has been disabled and the external thermostat was in total control of the whole unit via the Aube-RC840T-240.

109A_5

Hello @TBL194,
In either case were the heater controls preset for it to heat ? Does it still work normally without the added Aube-RC840T-240 wiring ?

TBL194 said:

@109A_5 So just so I understand, the first one will work the heater and fan so basically the tstat just turns it on and off? Send second work just works the coil and not the fan?

I did both examples, both make turn the tstat on but neither one turns the heater on?

TBL194

@109A_5 GM, the unit works fine without the Aube. The first option the unit has no power at all but the Aube lights up to trigger it on but nothing happens. It seem like that option will work if we can figure the wiring out. And yes the tstat on the unit was preset to be on. I would be fine with an on and off. That should be doable right? Appreciate all your time and knowledge.

TBL194

@109A_5   Should the red of the Aube have 120 volts coming out? 

pecmsg

TBL194 said:

@109A_5   Should the red of the Aube a have 120 volts coming out? 

Be very careful with electric. 
Red wire to What? You need 2 points to measure voltage. 

The only time you measure voltage to ground is to confirm it’s not energized!

TBL194

@pecmsg The red wire coming out of the Aube 240 volt transformer. I am reading no voltage on the red and I believe that is why this isn't working.

pecmsg

Reading RED to what?

TBL194

@pecmsg to ground. Makes no sense the red doesn't have 120

pecmsg

Then that wires not energized. 

My point it you need to measure to the incoming voltage. L1 to L2

109A_5

Hello @TBL194,
Using this wiring diagram below, there is 240 VAC across the Black and White Building wires, it is a 240 VAC heater. From either Black or White wire to ground there is 120 VAC. In this case the White wire is used as a 2nd Hot wire, for a 240 VAC supply.

The Black and Blue wire of the Aube-RC840T-240 supplies power to the transformer in the Aube-RC840T-240 and 24 VAC for the external thermostat and the relay coil inside the Aube-RC840T-240.

During a call for heat the switch in the thermostat closes energizing the Aube-RC840T-240's relay coil closing the relay contacts. The relay contacts close connecting the Black to the Red wire of the Aube-RC840T-240.

This provides 240 VAC to (or across) L1 and L2 of the heater. If the heater controls are preset correctly, the heater should come on UNLESS the heater need to be commanded on by a human after the power is applied to it, due to the possible safety functionality of the internal electronics board.

TBL194

@109A_5 Ok kinda making sense. You're first scenario you presented above where you first commented on the thread the red wire from the Aube was connected to the heavy red of the heater should have worked if the red wire of the Aube was putting out 120vac? I take it this didn't work cause the Aube red wire didn't not have 120vac due to it being faulty after I tested that lead and it was 0. Basically all I am trying to get at is the red on the Aube should provide 120vac to trigger the heater on from the heavy red.

109A_5

Hello @TBL194,
My original post has two possible control scenarios.
Example #1 the Aube-RC840T-240 would switch the whole heater unit on or off.
Example #2 the Aube-RC840T-240 would switch just the heating element on or off, and may leave the fan running when not needed.

OK found the issue with the second example. The heater relay on the electronics board switches the L2 circuit. The Aube-RC840T-240 switches the L1 circuit.

So the original instructions should have read "Remove the Heavy Black wire to heating element from L1 on the terminal block and connect it to the Red wire of the Aube-RC840T-240." And has been corrected.

Also in either case the electronics board would still have control if its thermostat is satisfied first.

You really need to think of the heater as a 240 VAC device between L1 and L2. Since if the building wiring is wrong you could have 120 VAC on either hot wire to Ground and have Zero Volts where 240 VAC should be.

TBL194

@109A_5 ok, to know if my Aube is not faulty should the red being putting out 120vac?

109A_5

Hello @TBL194,

TBL194 said:

@109A_5 ok, to know if my Aube is not faulty should the red being putting out 120vac?

You could think of it that way but it can may misleading. Since you may see 120 VAC from the other Hot leg through the load.

When the Aube-RC840T-240 is Off or relay is de-energized you should have 240 VAC across Black and Red wires of the Aube-RC840T-240. When the Aube-RC840T-240 is On, relay is energized there should be Zero Volts across its Black and Red wires, putting 240 VAC across the load.

TBL194

@109A_5 Just did both examples and still doesn't work. Has to be a bad Aube. I checked L1 and L2 from the first example and have 0 voltage across L1 and L2 even when the Aube kicks on. When I bypass the Aube and direct connect to L1 and L2 to heater it has 240.

109A_5

Hello @TBL194,
Well looking at your first picture, the Red and the Black wires (the relay contacts) of the Aube-RC840T-240 were across the 240 VAC power. If somehow (maybe the Blue wire touched something) and the relay in the Aube-RC840T-240 was energized the relay contacts could have been damaged.

TBL194

@109A_5 the fact that all of your examples don't work has to be a faulty aube. 

TBL194

@109A_5 After all that bs the damn Aube was bad. Works like a champ now with new one. Thanks for all the help to make it work!