The Richmond model that we just had installed yesterday draws 6 amps, and when I called Lennox to see what the furnace pulled, they said 9 amps, so guess what two got the same circuit. Lennox gave the ok that I could hook the Power vent W/H unit to the same 20 amp line that the furnace is on. The Power Vent that goes on top, has a Ground pigtail that connects to the water heater tank, which then allows it to be grounded.
As for a certain someone and the other stating that it needs a gfci breaker or outlet, the following is from the manual for the same unit that Rheem rebadged as their Richmond line, that I have.
The maximum current draw is
approximately 5.0 amps ..
The water heater must be electrically
grounded in accordance with local
codes, or, in the absence of local codes,
in accordance with latest edition of the
National Electric Code ANSI/NFPA No ..
70 ..Refer to the figures below for water
heater internal wiring .
NOTE: It is not recommended that this
unit be installed on a GFCI circuit.
http://www.rheem.com/documents/power-vent-power-vent-use-and-care-manual
From the info for their tankless model:
Power Cord
• The electric power supply requirement for this
water heater is 120 VAC/60 Hz, 2 amps.
• A dedicated circuit is recommended for the water
heater. Do not connect to a GFCI or AFCI circuit.
Multiple units may be connected to a single
circuit up to the circuit rating.
• Do not use 3-prong to 2-prong adapters. Do not
use power strips or multiple outlet adapters.
http://www.rheem.com/documents/tankless-h84-outdoor-tankless-condensing-unit-use-and-care-manual