Freeze protection for hydronic pole barn heating

[Conde]

My father built a pole barn with in-floor hydronic heating. We are just now getting around to adding the heat source (7kw Electro industries Off-peak boiler).

He is located in Minneapolis MN so the 99% design temperature is -9.4°F.

We are looking to use a Cryo-tek 100 anti-freeze mixture.

In relation to the design temperature, which protection rating should we be targeting? Both category and temperature?

Thanks

 

[Fitter30]

• Propylene glycol needs to be a minimum of 30% for the inhibitors to protect the system. Go with 100% pump, boiler and piping is above ground. Just for some information jan 31 2019 air temp was -31* f 2" in the ground 22*f
• https://sroc.cfans.umn.edu/weather?page=114