we're looking to move our operation into a larger building. the space we're strongly considering is without any heat source in the warehouse/shop space. i only have experience with gas blower heaters (existing in all the spaces i've ever been in). these are okay, but we open the doors a fair amount so they run a lot of the day. not having very good insulation doesn't help either.

aside from in-floor radiant heat (cost-prohibitive), what heat supply should i be considering? i've read stuff about overhead, radiant tube heaters but don't have any experience with them.

we're in the mid-atlantic with mild winters.

Lots of insulation is the best heating solution. Works year round. Natural gas is the cheapest, and some overhead door air curtain heaters take care of the door issue.

Put vinyl flaps on the doors

We let the vac pumps help heat in the winter and direct outside in the summer

Gas furnace to take the chill out

Yes, lots of insulation

We run leaf blowers once a week for house keeping

If its a larger space why would you be opening the doors as much? Is this new space not large enough still? Are you bringing that many trucks inside? I agree with the insulation, just finishing that up myself. Just put in a gas heater as well, works like a champ and I'm in western Colorado where it gets pretty chilly. One option to think about is maybe making a transition area between the heated shop space and the loading/unloading area, think grocery store front entrance with its 2 sets of doors. Are you looking at buying this space or just leasing it? If buying it, see if you could put infloor heat somehow. Its makes a really nice work space and the objects are heated, not the air. I just left a space that had infloor heat and I wish my new space had it. As far as heat source, I agree that gas is the best but if you can put in a wood fired boiler than your solid wood scraps can be converted to heat. You can use that with in floor heat tubes or a heat exchanger. Only drawback is that if you leave on vacation, someone has to keep it stoked once or twice a day. All of this depends on if you can even burn wood where this is located, city or county regulations may dictate your decision.

Dustin mentioned putting in a wood waste boiler; we did install one of these in 2014. When it is heated up, and it has to be at 190 degrees F, it works fine. However, I'm not sure it is really economical. We burn everything, but there is time involved in feeding the boiler. Also, as Dustin mentioned, you have to keep it stocked when you are not there or it takes a long time to heat up on Monday morning. If you get one of these, you will still need logs to fuel it, scraps burn quickly and you need logs to fuel it over night. I installed a gas hot water heater in line to keep the temperature of the water up when we were gone. This worked fine until the sensor in the hot water heater went out. Hot water heaters are set so that the burner will go out if the temperature goes over 180 F. It costs $300 to replace this control and I have not replaced it. Also, in 2014, EPA mandated changes to Wood Boilers to make them more efficient. I bought mine in 2014. The newer models force the smoke down and up the back through some tubes and these have to be cleaned fairly often. To be honest, this was a pain in the ass, but with the three wall mounted radiator units with fans, when it is cold, the shop is warm and I am in Northern Michigan where we get snow and cold temperatures.

I've got a 25,000' metal building with 4" of fiberglass insulation. Heating is gas fired overhead infrared tubes. I like them much better than rental buildings I had with the typical gas unit heaters with fans. This building has been added on to twice, each time with different brands of infrared heat. There is a difference in the quality of the units. One brand has been terrible, one very good.
If you have a spray booth you need some way of air make up. The best solution is direct fire right into the booth.
Overhead doors dump a huge amount of heated air when opened and tend to be leaky otherwise. The "weather seals" are prone to failure. We have shelters on our loading docks that help a lot but are still prone to leaking as long as there is a truck & open door. The shelters are also prone to damage by drivers that never learned how to back a semi.
If at all possible, put in more insulation. It only costs once, gas is ongoing.
I'm in Nebraska where it gets chilly, it only gets below zero for a couple of weeks each year.