Do i need special ball valve for hot water heating system? Is WOG rating ok?
You're fine
Ordinary WOG (water, oil, gas) rated, metal-bodied ball valves are going to be rated for hydronic temperatures and beyond; if you want to make extra sure, you can check the specifications of the valve you're looking at for a WSP (Working Steam Pressure) rating, which a typical ball valve (using the Watts LFFBV as an example) will have as well.  (Obviously, a plastic-bodied valve is going to have a much lower working temperature rating, and no WSP rating for that matter.)