Thinking out a heater for small garage, wiring

[fastbroshi]

Hey Everybody,

I was looking for some clarification and suggestion on materials and possibly where to get them for a planned install of a 5K watt, 240v electric heater. I had a couple questions coming up while I'm browsing for materials:

1. Does that sound like sufficient capacity for a 430 sqft garage? One big uninsulated door, no insulation above. Floor is epoxy coated, not sure if that helps. This garage is actually attached to the house so it shares one "heated" wall. I do actually plan on insulating the door and above though.
2. The heaters I've ran across in the 15k capacity seem to pull upwards of 18 amps, so I figure a 30-amp circuit would do here. Problem is, I can't find any 30-amp 240v receptacles. Maybe I'm searching for the wrong thing. Can someone recommend one?
3. Since we're going 30-amp, I figure 10 guage wiring, but which kind? I'm not sure if I'm looking for 10/3 or 10/4. Can someone explain which one I need andy why?
4. Breaker - I don't understand if I need a double pole 15-amp or 30-amp breaker, or even if it needs to be one linked breaker connected together or what. What's the proper one to use?

I know these may sound uninformed, but do little to no electrical with my house. I can install fans, appliances and such but I've never added a circuit before and I want to know I'm using exactly the right materials before I start working. I've been reading for a bit but I'm not finding what I'm looking for.

Thanks!

 

[agrasyuk]

2. No recepticles - hardwire it.

4. Since it's 240 volt you will use a double pole breaker of 30 amp capacity. Being double pole it will have a footprint of two normal breakers, that way it taps into both phases that come in to the bus rails from the main breaker.

But really it will be of no use. I'm in the same situation - one wall attached, uninsulated attic , big double door (albeit with good insulating panels), asked for advice here, received negative reply, thought "I'm obviously smarter then that, I know better". except I wasn't, it didn't work to well. Yes it got hotter but not for long. And then the bill came in...

My advice (the same that I received and didn't take) hang drywall on the ceiling if possible and insulate. Thats what I will be working on soon.

Regards and good luck.

 

[fastbroshi]

Thanks for the response on the receptical. If wiring it directly is the solution, I'm thinking conduit through the attic is the proper way, but how is the junction to and through the drywall done?


Just to clarify, my garage is fully enclosed and it does have a drywall ceiling. There's just no insulation above it. Other than the door, the other three walls are insulated per usual.

 

[agrasyuk]

In that case you are much better off. I guess I missed the fact you actually have ceiling.

The junction will be done in a way very similar to how you have your dishwasher or electric range/oven is wired - junction box on ceiling with cover that has adapter for flexible conduit (just a hole for the fitting).

Not to say that you absolutely can't do recepticle , they do have those for very high amp devices too. Will look something like this

Or specifically for 30amp something like this (although not sure if this one is 2 phase)

If the heater has a plug instead of bare wires you sure can get matching recepticle to that specific plug and the manual will specify which one you need to get. That said I will be very surprised if the heating appliance you get will have a plug.


At any rate, I highly advise you to speak to electrical pro. I do my own wiring, have run 50amp line run to secondary breaker box in garage for the lathe
and the hearing attempt but I'm not a pro by no means. I understand the spirit of DIY, but judging by your questions it seems you are not completely comfortable. The thing is that electrical mistakes can lead to fires, cause will be dicovered in no time and insurance company might refuse helping. Just my 2 cents

Good luck!

 

[Bolson32]

You just use a junction box, you can buy premade flexible 10ga whips that have all the wiring you need in them. That's what I used.

I would probably just run the conduit surface mounted and keep it exposed, that's the real reason for conduit anyway. Then if you ever need to mess with it you're not digging around your insulated attic.

Also, since you have a ceiling and the walls are insulated I bet it will heat up pretty nicely but I'd blow the attic full of cellulose, cheap and easy and you'd save that money in heating costs pretty quickly.

 

[TractorJeff]

10-2 w/ ground, 30 amp double breaker(kind where the 2 levers are pinned together), run wire inside of wall to attic, across attic to a junction box where the receptacle will go. If it is a hard wire, then it will be a whip and a grommet.

 

[zmaxmotorsports]

What are the actual specs on the heater? +18 amps doesn't mean you need a 30a circuit.
As long as the wire is protected in the attic theres,no need to run it in conduit,nm will work.
Also,what brand of service panel do you have?

 

[Bolson32]

What are the actual specs on the heater? +18 amps doesn't mean you need a 30a circuit.
As long as the wire is protected in the attic theres,no need to run it in conduit,nm will work.
Also,what brand of service panel do you have?

5000w/240v = 20.833amps. Needs a 30 amp breaker, especially with heaters requiring 20% overhead for continuous operation.

 

[zmaxmotorsports]

5000w/240v = 20.833amps. Needs a 30 amp breaker, especially with heaters requiring 20% overhead for continuous operation.

He didn't post that useful piece of info.
But depending on the brand of panel he has,it could also be put on a 25a breaker .

 

[Bolson32]

He didn't post that useful piece of info.
But depending on the brand of panel he has,it could also be put on a 25a breaker .

Yea, most of them can for a 30 on the wiring diagrams

Sent from my SM-G935V using Tapatalk

 

[ford33]

I have a small 5k electric heater in a 2-car garage in Chicago with 10 foot walls. The garage is insulated very well and the little heater will keep it warm (60F) in the typical winter. But I have noticed that mounting the heater near the ceiling keeps the heat near the ceiling. It is noticeably warmer near the ceiling compared to the floor.

I installed a ceiling fan in the garage and run it with the airflow going down. This distributes the warm air throughout the garage and makes it more comfortable in the winter. It made a difference. You should also consider a ceiling fan to distribute the air in the garage. Install electrical for the fan when you do the heater.

 

[AdamIsAdam]

Subscribed. I've got a 600 sf detached garage that's 50% below grade and has another garage above, so my ceiling is concrete too. 2 car garage doors. 8' ceiling. Uninsulated.

Will a 5,000 watt 17,000 BTU unit be enough
https://www.northerntool.com/shop/tools/product_200578579_200578579?MobileOptOut=1

or do I need a 7,500 / 25k BTU?
https://www.northerntool.com/shop/tools/product_200631888_200631888


I'd prefer the larger one, but looks like I'll need substantially heavier wire. Calls for 8ga. What size wire does the first one require?

 

[jvitez]

For your uninsulated concrete garage even 7500W may not be enough, as that much concrete is a monster heat sink. You could always add a second heater is one isn't enough.

5000W/240V= 20.83 amps, x 1.25 for continuous use= 26.0 amps, rounded up to next nearest standard breaker size is 30 amps, which requires 10 gauge copper.

7500/240=31.25 x 1.25 = 39.0 amps, rounds to 40 amps, which is 8 gauge.

 

[AdamIsAdam]

ok, thanks. I'm going to try and get the 8ga wire run and hope that the 7500 unit does the trick, at least enough to take the edge off in the winter. I may run a fan or two in there to help circulate the warm air.

Are these the best units for the money? Are some better at heating a room than others of the same size?

 

[Bolson32]

For the money, they're probably the best electric heat you can get. Tough to beat the price and relatively easy installation.

 

[jvitez]

Those heaters are made in China. Depends how long you want to be there, or if Buy American is important to you. You really can't beat the price.

I paid $419 CDN ($330 USD at today's exchange) for a 5000w ceiling mounter fan forced heater, made in Canada.