On 1/29/2015 9:13 PM, gary wrote:
I have 2 water heaters, plumbed in series.

1 is turned off, as 1 is normally adequate.

Would like to be able to turn heater "ON", remotely via internet/wifi,
when I will need more that the usual amount.

thanks

gary

Google will get you many options.
Looks like the whole shebang can cost you $300.
Plus permit fees and inspections should you decide
to be compliant with local building codes.

But...
Have you done the math?

When I looked at water heater setback, I concluded
that the thermal time constant of the heater was so
long that I would save almost zip by turning it off.
Takes only slightly more energy to heat it back up than I saved
by turning it off. The better the tank insulation, the
less you save.

In your case, you're gonna heat up 50 gallons of water then
let it all cool back down when you're done.
Might be more cost effective to raise the main heater temperature
a few degrees to get that extra capacity most of the time.
The devil is in the details of usage. You have to do the math.

If you need this functionality frequently and are unable to
plan ahead, you might find that the payback is less than never...maybe.