Recirc loop insulation – GreenBuildingAdvisor

Space constraints are driving me towards a gas tankless water heater. I’m looking at the Rinnai RSC160in b/c it’s on a big sale, plus I could get rebates, and thinking I would utilize the recirculation feature. 

Does anyone have any ideas for affordable ways to boost insulation of the hot water loop? I see the regular foam pipe insulation that’s like R3, but I’d prefer to increase that substantially if possible. My reasoning is, if I’m gonna have recirc, I’d like it to be available pretty regularly, and I don’t like having to push buttons 30 seconds ahead of using water. So, I envision keeping the hot water loop “charged” for a good portion of the day. And to do that I want it to be insulated well enough that standby losses are kept manageable.

Or if this is a bad idea all in all, please let me know why.

Thanks!