Elect. W/H Looped To Geothermal

[neolitic]

A good customer had a geothermal
heat pump installed a couple years ago.
I just noticed that they plumbed
a loop to the electric water heater.
They replaced the drain cock with a
copper nipple when they looped in.
Am I missing something,or isn't this
setting up a situation for the early demise
of the water heater?
Looks like a brass nipple should have
been used for this.

Besides wanting to help out a good client,
I just had the heater put in 3 years ago
as part of a bath remodel I did for her
and I'm not up for any problems for my
warranty....especially since that plumber
retired last year.
TIA


EDIT TO ADD:
Geothermal guys are coming out next week.
They already told the customer, over the phone
that this dis-similar metals thing is an old wives tale,
so some sort of citation from a recognized
source would be nice if I'm right about this.

[neolitic]

Just a bump.

[Redwood]

Probably not if its a closed system.

[neolitic]

Probably not if its a closed system.

Closed how?
I think they're using the heat pump
to pre heat for the W/H.