Best Heat Source Based on Heat Load?

[MyShopBoss]

I recently had a heat load calc done on my shop (details below). Now I'm looking for a good !economical! heat source. I'd really like a dual-purpose condensing boiler but I just can't justify it right now. So, I'm looking for other options. I like the idea of a dual-purpose unit so I don't need to purchase something else for the sink, etc. but it's not a requirement. I'd also like something that hangs on the wall, but, again it's not a requirement. I use LP.

What are my best options for a heat source with my give scenario?
What do you all use for domestic hot water when using a single-purpose heat source?

Dimensions: 30X64
R19 walls
R40 ceiling
1 - 7X18 overhead door
1 - 36" walk-in door
4 - 24"X30" insulated windows
Energy factor: .5
Temp difference: 50
Heat Required (BTU's/Hour): 48000
Heat Produced By The Floor: 76800

 

[aandpdan]

How much hot water do you need? Is it just for a sink?

Small electric.

 

[MyShopBoss]

I have a sink in the bathroom and there will be a hose in the shop area to wash vehicles, etc. My main concern right now is what size (and brand) boiler do I need. I've got two different quotes so far, and they are very different. One of the guys I know well and is building contractor and licensed plumber but self-taught when it comes to radiant heat. I don't know much about the other guy but he claims to have done a lot of installs. I was hoping to get a ball-park estimate from someone on this forum that will push me to one direction or the other.