Need help with circulator sizing

[rockcrawl]

I'm hoping someone can give me a good idea what size circulator I need.

1500sf garage
well insulated, PA climate
(3) 400ft loops of 1/2" PEX in slab
32 gal oil fired water heater http://rightspec.bradfordwhite.com/Specs/650.pdf

[KField]

I don't think you would go wrong with the Taco 0011. It may be slightly oversize but your 400 foot loops are 100 feet over the max we use for 1/2" tube. You may need the extra head to overcome the friction.

Ken