Adding Space Wall Heaters

Question

I am thinking of installing three wall space heaters in the basement I am renovating. I currently have three cables coming into the basement:

• 1 - 20amp for the bathroom GFCI that will power the fan,
• 1 - 20a for all of the wall sockets and
• 1 - 15amp for the bedroom and bathroom lighting

Here is the problem: I need a space heater for the bedroom, bathroom and two for the main living area.

My thoughts are because each unit pulls a maximum of 8.3amps that I can put two heaters on one 20amp breaker or do you think each heater would require its own dedicated 20amp breaker

What am I installing? This Cadet CEC163TW Energy Plus Wall Heater
1600 Watts at 240 volts; 1500 watts at 208 volts; 1000 watts at 120 Volts.
The cool thing about this heater is a unique power supply smart sensor auto-adjusts the heater voltage to match your voltage supply.

Answer 1

Wrong heater

I don't know what possessed you to pick that one, but you can get far cheaper Cadet heaters. A heater of that size should cost $50-100. All of them are 100% efficient - an electric heater that is less than 100% efficient is impossible.

That "cool feature" is actually 100% useless to the consumer. You know your voltage so you can buy a much simpler single-voltage heater that has fewer failure points. That "feature" is only cool to contractors, who get to stock only 1 heater and simply pass the feature cost on to the customer.

So I think I just saved you about $400 :) Now we can fund the circuit(s) needed to do the job.

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This unit is 8.3 amps @ 120V. Because it is a heater, we must provision for 125% of that ampacity, so we must provision at 10.4 amps per heater. Welcome to 120V heating.

Not enough capacity on the circuits.

It must be hardwired. When a hardwired load is more than 50% of circuit ampacity, that circuit cannot have any receptacles. Even one on the wall circuit will be >50% ampacity (10.4 amps) and will require removal of all receptacles. Two just won't fit (20.8 amps).

So that means the bedroom lighting circuit can handle 1. (but the lights better be LED).

Use of the bathroom receptacle circuit is out of the question. That can only be used for bathroom receptacles OR loads inside one bathroom.

So we can't get there from here.

Since we have to run a new circuit anyway...

you can just run a 240V/20A circuit with #12 wire. That will be 4800W on paper and will support up to 3840W of heaters. (3840 x 125% = 4800).

Cadet baseboard heaters are laughably cheap. These are dog simple and will last 40 years.

2000W baseboard -- $65 due to demand, normally $50.
1500W baseboard -- $57 ditto.
1250, 1000 and 750W also available.
Add up to 3 thermostats at $15 each.

If you really want fan units, here's 3000W in one unit ($181) Or two 1500W fan units, $126 each. Or 1000W unit same price.

See how that "feature" doesn't make any sense when you know your voltage? It simply adds electronics that creates a failure point.

Answer 2

You're gonna a bigger boat. According to code, a bathroom requires it's own 20 amp dedicated circuit.

I looked up the amp draw on the heaters you mentioned and I think you might have not interpreted the ratings correctly: 1) at 120 volts, the heater will produce 1,000 watts at 8.3 amps 2) at 240 volts, the heater will produce 1,600 watts of heat at 6.7 amps. 3) at 203 volts, the heater will produce 1,500 watts of heat at 7.2 amps.

So even if it was code legal, connecting permanently installed electric space heaters on a 120 volt circuit would seriously overload the circuits. Also bear in mind that electric space heaters are considered a "continuous load" and must be derated by 20% IE: even though 120 volts x 20 amps = 2,400 watts, you can only load that circuit up to 1,920 watts (2,400 * 80%).

Is it practical to run additional cables from your main panel? Running those cables at 240 would enable you to run 2 heaters on the same cable.

Not meaning to be too assertive, but at the end of the day, think about what you're doing: Trying to add 4 space heaters that has high power requirements to existing wiring! They will also be expensive to operate.

I know they are a lot more expensive, but have you considered a mini-split system? They are very efficient and as a bonus you get A/C as well.

Sorry, but I think you'll need a bigger boat.

Answer 3

you can get 2 of your heaters on one 20amp 240v circuit.

these circuits should only be for heaters.

so yeah, 2 new wires going to the panel.