Recirculation for Tankless WH

[Bodishr]

I'm planning to install a Rinnai gas TWH. This is a whole house unit, new construction, PEX piping. I will have a hot water return line, and I want to add a recirc pump with a small storage tank to eliminate delivery wait time. Basically, I'm making my own hybrid heater. Can anybody suggest a type/source of insulated tank to use? Based on my research, something in the 2-4 gallon range should be sufficient, but I'm not finding much available for domestic hot water outside of pressurized expansion tanks and point of use water heaters. Any thoughts on recirc pumps would be most welcome too.

Thanks,
Rick

 

[Mr_David]

Grunfros Recirc pumps is what we use. Don't over size it. You just want it to move the water.
Get the flanged type. Easier to replace. They also have the option of built in timers so they don't run 24/7
Just use a small electric water heater, You can even energize it for a back up.
You could even use the electric to keep the loop hot and when you have a hot water demand the Rinnai kicks in.