The good thing is the need for heat this year is about over.
My heat now is a pellet stove. It was very good for about three years. Then the problems began. Replaced a $400 cucuit board but still having problems. Called the help line trying things they said nothing working. So not gonna spend any more on it. New one is about $1400. Prolly gonna get something different. I been looking at a 7500 watt electric. Dont know about the operating cost tho. My shop is 22x24 The walls are insulated very well but no ceiling. Just insulation stuffed in the eaves. Anybody used this type of heater before? Also dont know if this is the best brand to get. This on is about $600 and 220 v

My shop is 14X28, I have an 18K BTU window unit that heats and cools, it does a good job but is getting up there in age. My shop is insulated top to bottom and holds heat well, lately I have been using a little 1500 watt space heater to warm the place. If I plan to work in the afternoon I turn the little hater on in the early morning, by noon the shop is warm enough to not get chilled, around 60 degrees which what I like.

If I were you I would fill in your ceiling and blow some insulation over the rafters, a well insulated shop is easy to heat.

I built a drying box with 3 100 watt bulbs in it, the most I could get out of it in my unheated garage in the winter was 90 degrees. I stuck some foil backed foam on the plywood and could get 150 degrees inside it. I had to put a rheostat on the bulbs to keep the temperature down, barely glowing they bring the box to 90 degrees.

Insulation is the key.

I have seen quite a few of those installed garages around here. I am sure it will do the job, but electric heat is not the most economical and I don't think you will be very happy with the associated bills.
Any reason you are not considering a wood stove? You already have a solid fuel stove pipe installed.

First thing you want to do is close off the ceiling, I'd use 4x8 sheets of particle board or 1/2" plywood. Then insulate the crap out of it, a good 9" of insulation. The biggest heat loss is through the ceiling.

If you have natural gas there, maybe a good gas heater mounted up in the ceiling, but they are pricy. Electric heat will kill your electric bill! Or better yet, get a used hot air gas or oil furnace and just put a 90 degree shaped plenum right on top of where the air comes out. I promise you that will heat your shop quickly.

I use a small wood burner in my shop and have to be careful not to put too much wood in it or it gets very warm in the shop. My shop is super insulated and it's 27 x 13 inside.

If you have access to firewood, a small wood burner will do the job too. But it would be nice to just flip a switch and the furnace starts to run, especially for a guy 72 years old:)

Have you looked into inferred radiant heaters. I've seen them in all size shops from small to very large and I think they are more efficient that the coil type heater you have there.

does the feeder motor still work in the pellet stove?  what fuel do you use in the house?

Yeah the feeder works. The other two fans are about to need replacing.
Get natural gas in the house. Prolly gonna run a line out to the shop and buy a heater.

Mike check into a used gas fired hot air furnace first, or even a small new one..

Compare prices with the heater ya wanna get.

some of those variable output gas burners can run at pretty low rates. i think you will like the even heat once you insulate

I think this would work.
https://www.northerntool.com/shop/tools/product_200577749_200577749?utm_source=CSE&utm_medium=Shopzilla&utm_campaign=Heaters%20&%20Stoves%20%2B%20Fireplaces%20%3E%20Natural%20Gas%20Heaters&utm_content=27457&cnxclid=16150796813472136611710090302008005&szredirectid=16150796813472136611710090302008005

That and plywood on ceiling and insulation and you are set.

I had a 75,000 btu gas heater like that in my shop for a while. Had to get rid of it, is was so loud and constantly cycling on and off, it drove me nuts. Only time it did not bother me was when it was drowned out by machine noise.

Same brand as that one or different ? The pellet stove runs all the time also. Kinda tune it out after a while.

Different brand. I've seen a quite a few of those heaters, they are made to be in a garage for a reason. Don't think you will ever see one in living spaces. They work well and will certainly heat up your shop. It's going to be about 10x louder than a pellet stove. I would check out a running unit somewhere to hear if its something that won't bother you.

My shop is is 2 story with about 1/2 loft. I got a 220 commercial hvac heater with blower. It was built to keep homes under construction warm at night so the sheetrock mud dried buy morning. It is portable and has a thermostat and works well, heats my shop up in about 20 minutes and the heat rises to the upstairs which acts as a warm air dryer for sliw drying my wood.

I use these oilfilled electric heaters. They are on 24 hours and keep the shop nice and warm. Besides I have a wood stove. Here in Norway electrisity is less expensive than in most countries so that is what we use for cooking and water heating also.

Stic...  Go find you an old electric clothes dryer on Craigslist for about $50 and a couple of 200 watt heat lamps put in strategic areas...  That should get you there for the rest of the season...  Research it and buy the real deal next winter... That way you get one extra season out of it before it breaks down...   

  It's funny that you are all talking about heat when I am about to chop a hole in my roof in the next week or two and put a ventilating fan in to get rid of some heat when the summer comes...  With the new, nice white roof and a fan my shop should be cooler than it's ever been in the summer... Definitely looking forward to that... It sucks sweating on your work...  Maple really does not like that...

Here is a pic if mine. Vents at the bottom on all 4 sides. Air filters on top.

Not familiar with hvac unit. Is that all electric ?

Yes Mike