Yes, there is a drain valve. On my rads they have always been right near the lower rad hose & the valve is a red thumscrew that takes a long flatblade screwdriver to turn. Sometimes they get stuck or don't drain so well. Recently I had to remove the rad hose. Removing the rad hose also seems to get a little more out and you can shine a light inside to see if the hose is scaled up or not.

Regards,

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Brian Toscano