Will chain be ok if left on a radiator to dry?

It really depends on what type of chain you're talking about, ( bicycle or motorcycle ), and what you washed it with. I always used kerosene and a brush to wash my motorcycle chain. Two to three washings and a final drying with a soft towel usually removed all the dirt and grime from the chain. The oil in the kerosene actually helps lubricate the chain before your normal chain lube is applied after remounting the chain. A bicycle chain can be cleaned and dried in a similar way using whatever lubricant you normally use on the bicycle chain. Just don't use anything like WD-40 on a chain! It's abrasive! I've cleaned my chains, bicycle and motorcycle, and been back on the road within and hour after the chain was remounted and lubed. The kerosene makes the job quicker, as it's a bit of a lubricant itself. I used this method for the 10 years I rode motorcycles, and the past 50 years I've been riding and maintaining my bicycles. The secret is not to use any lubricant that attracts dust and dirt. I prefer a "dry" lubricant specially made for motorcycle chains. Of course the "best" way to lubricate any chain is to allow it to soak in the type of lubricant you'll be using, but just following the instructions for the lubricant you favor should be fine. The "dry" lubricant I used was just sprayed on and allowed to dry for a few minutes. It was not "thrown" off of the motorcycle chain, even at highway speeds.