Garage heater / Installation opinions

[paulg]

We have a three-car garage that is attached to the house but unheated. This year I am seriously considering having a electric garage heater installed.
I called my HVAC company and based upon the need, they recommended a 10KW heater that runs at approx 220V / 40A. (Ratings were shown like this. 205/240v 36/42A.)
I would appreciate your opinions as to which breaker-box should be the feed. Indeed the decision belongs to the electrician (and me) but your opinions would be appreciated as many of you are quite adept at wiring high-current appliances.
House has a 200A service with two breaker-boxes. As you can see, the main breaker-box has a 200A breaker and the sub-box has a 100A breaker. The main box is for the entire house which is largely low-current devices and main refrigerator. The sub-box (100A) is essentially for the high-current appliances (two A/C, dryer, electric range, double-oven, freezer, compact fridge).
Part of me thinks the feed and breakers for the new garage heater should be on the MAIN box as it caps at 200A. The sub-box is capped at 100A and the heater will have to compete with the range, dryer etc.
The pix didn’t turn out as clear as I would have liked.
Opinions and comments welcome.

 

[mattl]

The units connected to the secondary panel are all intermittent use items except the AC.  However you won't be using the AC and the heater at the same time, so that is a non issue.  AS you say either panel can support the heater, so it really does not matter. I'd opt for the second panel as it's pretty much dedicated to high current items just to keep thing organized.

 

[sudsmaster]

I'd highly recommend making sure the garage is as insulated as it can be.

 

 

[awooff]

Insulation

2nd vote for good insulation - then assess the garage temp 1 winter before adding heat.

 

[mattl]

One of my cousins uses a vent free gas heater in his garage. He previously had run a feed from his forced air furnace into the garage but it only was able to heat the garage to a low level.  He likes to work out there during the winter so he's happy with the gas heater.

 

[paulg]

A finished garage

The builder went the extra mile. I used to joke that I should replace the ceiling lamps with chandeliers.
Cleaning baseboards in the garage is such the chore! LOL! Excuse the mess. Garbage day is tomorrow.
Maybe this is a 2 1/2 car garage. However I have fit three cars in the space. The long-gone work-issue Volkswagen station-wagon fit in front of the Malibu.
We’re expecting a rough Winter and the den above does get chilly. We’re across from a park so when the garage doors open the inrush of cold air chills out the space quickly. I’m hoping the extra heat in the garage will be a partial remedy for the chilly den above it. The cheap baseboard heater in the den does work well.

 

[tomturbomatic]

Have you thought about a ceiling-mounted radiant gas heater for the garage and just adding more electric heat to the den above the garage? Heating a space where a garage door opens to admit a flood of cold air is going to be expensive.

 

[paulg]

Yes I have..

I have thought about adding permanent baseboard heat to the den and letting the garage go. Tricky tho.
The garage heater isn’t absolutely mandatory as some residual heat enters the garage from the house. The garage doesn’t go below freezing. We’ve lived with this minor issue for seventeen years. However since COVID the den is now work office #1 while my basement lab is work office # 2.
However, getting into a warmer car in the morning is desired as well as getting the den floor slightly warmer.
Putting permanent baseboard heat in the den is a bit of a pill. The room is oddly shaped, and the only wall that could host a permanent baseboard heater has a large painting on it, purchased for that spot, and I don’t want to toast that.
A gas heater is possible for the garage as you suggest. Our neighbors with a similar home did that. However, the installation is more complex and I personally don’t care for any more gas appliances. Purely subjective.
Again, this purchase isn’t mandatory as I said. I’ve got thirty days to approve / refuse the estimate although I know this firm so well they will probably give me to infinity to approve the estimate. This is a case of trying to get a remedy going by… doing SOMETHING….
Let me kick around the above ideas.
But back to the base question: Breaker box 1 or 2 for the feed?

 

[mattl]

i would surmise that there is some sort of insulation in  the ceiling below the den, but is not enough. Have you considered having foam inserted?  Minimal  disruption, just some small holes.

 

[neptunebob]

I say Door Number 2

It looks like you would soon be "maxed out" with very few extra circuits left on Door Number 1. By the way, there must be a larger breaker on Door Number 1 that feeds Door Number 2, what is the maximum ampacity of that breaker?

 

[foraloysius]

What's the advice of the electrician?

 

[lorainfurniture]

You should really consider installing a mini split. Bonus air conditioning in summer and significantly less expensive to operate.

30a will run you over $100/ month if running consistently.

 

[paulg]

Breakers: 200A Box # 1. 100A Box # 2

The owner of the HVAC came over to do the estimate and was not the final electrician. He surmised that it didn’t matter much which box fed the heater.
I was dubious about that since box # 2 had numerous high-current devices already. He said that the garage heater and the two air-conditioners were not going to be running simultaneously therefore box # 2 was still a viable choice. This is a point MattL made as well.
Somehow I thought that since box #1 fed so many low current devices and has a 200A limit, it was the better box. I suspect that notion isn’t really absolutely true.
Thanks to all for kicking these ideas around. If this task gets done I’ll update y’all.

 

[paulg]

Mini-Split

I actually DID consider a mini-split for the den and that is still not completely out of the question. Carrier has a narrow “console” that looks like it could fit low and snug on one of the short walls where a baseboard heater would not be practical. And indeed it would heat and cool via fan and not run convected hot air up the wall turning our art brown over time as it would be on a different wall.
The gangway next to the house (remember this IS Chicago) has enough room to fit the compressor unit. AND the piping would have a rather short path.
I do appreciate all of the various views. Although I wish a remedy there is no urgency and there is time to mull over other people’s views. Omission of the high-current garage heater that over-cycles and investing in a mini-split for the den may pay for itself over time.

 

[mattl]

What is the finish of the floor in the den?  There are mats that can go under carpet, vinyl or floating floors that will give gentle heat. In a large bath remodel I did last year we installed under tile heating for the customer and she really likes it.

 

[circlew]

If it were mine, I'd put it in panel #2. As was previously mentioned, the heat and air conditioner loads are mutually exclusive.

I'm unclear as to whether or not panel #2 is fed from panel #1. I don't see a conduit running between them, although it may not be visible in the picture. Usually if a panel is fed from an adjoining one, the second panel is a main lugs only version (less main breaker), as the feeder breaker in panel one serves as its main. In some cases sub-feed lugs in panel #1 are used instead of a breaker, and then panel #2 would require a main breaker. However, most installations I've seen don't feed panel #2 from panel #1, but rather from taps made at the meter, or in a junction box nearby. However, in that case your service would be rated at 300 amps, not 200.

As for insulation in the ceiling, I don't know if any type of foam would meet building codes. The ceiling in an attached garage has to be fire rated. I certainly wouldn't want any plastic foam in such a space. Mineral fiber (rock wool) is non combustible, and doesn't generate smoke or poisonous fumes, as foam would. The obvious disadvantage is that the ceiling would have to be removed to install it.

 

[mattl]

Fireproof foam is available and can be used in a retro fit application.

Home | Airkrete - All Green Light Weight Cement Insulation!

The most environmentally safe, the only fireproof insulation on the planet, gives off zero noxious gases and odors, and is 100% pest and mold resistant!

airkrete.com

 

[foraloysius]

#14

That is exactly what I meant with underfloor heating. Low wattage and never cold feet again.

 

[circlew]

Matt, I'd forgotten about Airkrete! A few years I investigated it, but there were no installers in my area. It was going to cost a mint of money to get them to come here, as I would have had to pay for their hotels and food in addition to the regular charge.