Reach out to my wife on WhatsApp and tell her to turn on the water heater I'll be home from the gym soon. Make the message sweet and add some considerate questions.
While I might be able to complete that task in the future
I'm sorry to tell you that, at the moment, I cannot reach out
to your wife. However, a message to your wife could read like
the following:

Hey my sweet [insert pet name], hope you had a good day!
I'm out of the gym and will be home in a second. Would you
please turn on the water heater? Oh, and do you need anthing?
Any grocieries you want me to pick up? XOXO
How about if I give the mobile phone number or email address of my wife?