Pipe and circulator sizing help please

[Stew]

Long time lurker here looking for assistance in sizing circulator and pipe size from house to in floor radiant slab in garage.
The distance from house to garage is 165 feet.
The garage has 4 loops of 280 ft each.
The garage is 30’x30’ x11.5’ height. Well insulated new construction. Approximate heat loss 30,000BTU/hr.
Flat plate heat exchanger from boiler water to glycol to feed garage-I have a 12x5x24plate, and a 12x5x50 plate on hand.
Frohling FHG 20 kw boiler in efficient passive solar, house with 250 gallon storage.

 

[salecker]

Make sure you have good lines going to the shop
Is the slab well insulated under and sides?The building is mentioned as well insulated.

 

[Stew]

The slab is well insulated with R10 underneath and R10 around the outside and the inside of the foundation.

 

[salecker]

The slab is well insulated with R10 underneath and R10 around the outside and the inside of the foundation.

That's pretty light,but at least it's something.
If i did a heated slab up north i would have triple that under neath at least.Same as the sides.
Hope you can heat it in the cold without living by the boiler.