My shop is heated with an electric boiler system to heat the slab floor with straight glycol circulated thorough pex tubing in the concrete.
No, it is too viscous (thick) and results in low flow. Even if flow wasn't a problem, it does not transfer heat as well at 100%. Pure ethylene glycol also has a higher freezing point than a 50/50 mixture. You should never use automotive glycol because of the additives like silicon that can damage the pump and boiler. Propylene is best and is nontoxic. Be sure to get the inhibited type to prevent corrosion. Boiler suppliers sell glycol made just for heating systems and it is readily available.
I'm not sure that pure glycol (ethylene glycol or propylene glycol) is used at 100% strength. They are diluted and used as antifreeze in various applications.
