PEX clearance to water heater flue?

Does anyone know the minimum clearance for PEX water supply next to a water heater flue (single wall)?


single wall vent - 6" to combustables…I think this situation would still apply
B vent, double wall - 1" to combustables

Thanks Darrell,
I knew it was 6 inches for plastic pipe, but was unsure of the Pex since it supposed to be good to 200 degrees.

“Keep tubing a minimum of 12 in. vertically or 6 in. horizontally from sources of heat…”
Above copied from:

Excellent handbook
Thanks Marcel