Wall Heater - Single Pole - 240V ??

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  #1  
Old 04-15-06, 11:07 PM
pendoreilleskie
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Wall Heater - Single Pole - 240V ??

I have three electric wall heaters to finish installing ... I have Berko R2004 ... hooked up to their own 20A double pole breaker with 12-2 running to the thermostat and continuing on to the heater unit (off of a panel with 200A service). In the wall box the grounds are tied together and the white is tied together, but the blacks are going to hook up to a single pole thermostat.

What amperage does the thermostat need to be? Do I need to use a thermostat that goes up to 20A?

I could have used single pole thermostats from the manf. that integrate in to the grill of the unit, but I would rather control with a thermostat on the wall so that my children are not turning the knobsj ... these thermostats have a max amperage of 25A, but could be used to control multiple units, which I am not doing.
 
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Old 04-16-06, 12:07 AM
bolide's Avatar
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> Do I need to use a thermostat that goes up to 20A?
Yes.

> these thermostats have a max amperage of 25A
That is fine.
 
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Old 04-17-06, 05:58 PM
pendoreilleskie
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So with the way my in wall heaters are set up using 12-2, it would appear for the wiring schematic for my heater that the thermostat only goes on one of the hot wires (single pole?), connecting my black wire from the breaker to the black wire on the unit (actually on the unit both wires are black but you can tell which one to put it on from the schematic)Berko R 2004

Page 3 of 4, Figure 6, mine is the "R Series Only"

When I go to the store I still need to buy a thermostat that works on 240, right?

As for the necessity of 20A, when I look at Table 1 on the same page it tells me that the draw for 2000W is 8.3A (I get the whole P=VI ... but I am curious, if the unit will draw a max of 8.3 amps, then:

1. Why use a double pole 20, and not a double pole 15?
2. What amperage does the thermostat really need (i.e. will anything over 8.3 A work - theoretically?)
 
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Old 04-17-06, 06:31 PM
bolide's Avatar
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> with the way my in wall heaters are set up using 12-2, it appears from
> the wiring schematic for my heater that the thermostat only goes on
> one of the hot wires, connecting my black wire from the breaker to the
> black wire on the unit (actually on the unit both wires are black but
> you can tell which one to put it on from the schematic)

This is legal.
It is necessary only to open one hot conductor to open the circuit.
Yes, the tstat is single pole in such a case.


> When I go to the store I still need to buy a thermostat that works on 240, right?

Correct, the tstat must be rated 250VAC minimum. It sees 240V.
If you put a meter on it, there is 240VAC when the tstat has the heater off.


> As for the necessity of 20A, when I look at Table 1 on the same page it tells
> me that the draw for 2000W is 8.3A
> but I am curious, if the unit will draw a max of 8.3 amps, then:
>
> 1. Why use a double pole 20, and not a double pole 15?

Someone chose it way back when it was installed, perhaps allowing for future upgrade to a higher wattage heater without changing the breaker.


> 2. What amperage does the thermostat really need,
> i.e. will anything over 8.3 A work - theoretically?

It would work. The problem is that the breaker won't protect it if it is under 20A. So if something goes mildly wrong with the heater, it could burn up an underrated tstat.
 
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