K.B.
Try a naptime routine that is similar to a bedtime routine. It doesn't have to be extensive, just consistent. My 2 year old daughter has a cup of milk while we watch an episode of Teletubbies (they actually make me a bit sleepy!) sitting on the couch togther. I'm not crazy about watching lots of tv, but they're calming and it keeps her in one spot for 30 mins. After that it is diaper change and in bed.
Give the little guy some cues and tell him naptime is coming. If he gets into a routine, he'll get used to sleeping/napping at your house.
Good luck!