Needed: High Efficiency NG HVAC for a 2,100 sf single story building

I've been asked by the owner of a theatrical company about heat for her building.  It is a single story, 36' x 57' building (almost 2,100 sf) with only a little bathroom partitioned off in one corner.  She is presently heating it with a wood stove but wants to run a NG line in and buy a furnace or two.  She wants to house film editing equipment and needs even heat but wants to get away from the wood stove work.  One estimate she got was for two wall heaters, one at each end of the building (there are already ceiling fans to move air in the summer time during live productions) over $5,000 for 94,000 BTUs.(nNo word on an efficiency ratingfor this one)  Another estimate she got was for a furnace and overhead ductwork (building has 9' ceilings) for well over $6,000.  The climate is Northern PA.

The inside of the walls are bare 2 x 4's which have been sprayed with 2 part foam maybe 4" thick and painted.  There are maybe 6 or 8 double hung windows (double pane) maybe 2' wide x 3' high.  The ceiling is made of insulated garage door panels and there are 2 overhead doors in one end.  I guess that makes it sound like it was a multi-car garage at one time!

This job is a tight budget job and I'm looking for some options and/or input for her since I'm a small contractor and an energy auditor and not someone who came from an HVAC background.

In our initial conversation I began steering her toward a sidewall vented unit.  I haven't run a Blower Door yet.  And it's been a while since I was at the building and then it wasn't to do an audit.

Questions---

Is it feasible to do something without ductwork?

We are in a more rural area. I have yet to find a HVAC co. who does Manual J calc's.  Do I need one?  and ---I've wondered this for a while, Can I learn to do one?

Thanks in advance!

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Thanks for the input -- 

Winter temps dipped to -15 F I think this January.  That has happened maybe 3x in the last 10 years so it's not always that cold but...

Forgot about a drain for the condensate.  I'm going up there to do an audit of insulation levels and airflow and I'll look at where to put the condensate.

Aren't mini-splits pricier than gas furnaces?

Once ductwork is considered a minisplit may actually be cheaper. It provides cooling also.

With a -15f temp the mini split ain’t gonna work.

Hello to everyone again -- it's been about a month (a very busy month) and I have been to the building -- I have some answers and another question about reading LOAD CALCULATIONS. 

The building has only 1.5" insulated garage door panels for the ceiling as the only insulation (in the attic floor along with 2 part foam on the perimeter walls averaging 2.5" to 4" thick) so I'm looking at blowing cellulose to a depth of 1' in the attic after some air-sealing to bring the heating loss down.  The blower door number was 6275 CFM@50 -- there is a construction flaw where 2 part foam applied to the perimeter's stud bays didn't completely reach up behind a top 2 x 6 band joist (is that what it's called if it's at the ceiling and not at floor level?)  Most bays are pulling air during the BD test.  Also the ceiling garage door panel joints are not caulked.  So I'm hoping to bring the CFM down to some reasonable level by caulking the cracks and using bagged inso stuffed into the stud bays.

I found an HVAC company that gets load calc's done and they gave a bid for a Bryant preferred two stage and ductwork installed inside the envelope (ceiling is 9'3").  They're sizing it at 100,000 BTUs.  

They did two load calc's -- one with minimal insulation (present situation) and one if 1' of cellulose is installed in 2052 sq. ft. of attic floor.

This is the first time I've read/seen an actual load calc so I have a question -- (the HVAC co. has a call into the guy in another city who did the calc and I'm still waiting for his answer) --- The software is "Elite RHVAC Residential HVAC Loads" and approved Manual J and Manual D -- 8th Edition, Version 2

On the first page, the "Project Report" down in the "Check Figures" section the number for square foot room area is correct at 2052 --- the "Volume (ft cubed) of Cond. Space" concerns me.  I would get this number by taking the sq. ft of 2052 and multiplying it by the ceiling height of 9.25' (9'3") for a total of  18,981 cu. ft --- The reports however had two different numbers -- minimal insulation calc being 32,832 and the insualtion added calc's number being 20,520.

Can anybody who knows this software tell me why these numbers are not the basic length x width x height number?

Is there a place on this report where I can see whether they considered all the ductwork is run inside the envelope not up in the attic?

And I don't see where the Blower Door number was addressed at all -- or isn't this the type of calc that uses the BD number?

According to both load calc's (minimal insulation) and ($2,000 more insulation added) I need a 100,000 BTU furnace.

Well -- thanks to everybody in advance for input.

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