Hello everyone - thanks in advance for any help/suggestions/advice. I don't know a lot about water heaters but am slowly learning as I go.

About three weeks ago, I had a brand new Whirlpool 40 gal electric water heater installed. About a week later, I noticed brown rust colored water coming out of the hot water faucets when I turned on the water first thing in the morning after the heater had sat unused overnight about 8 hours. If I went out of town for a few days and the heater was sitting unused for a longer time, then the rust colored hot water would be a darker brown color.

The rust colored hot water flows for less than five seconds when the hot water first makes it to the faucet. The water then becomes clear after a few seconds. I first noticed this about a week after installation and this has continued happening for the last couple of weeks.

This happens in all the hot water faucets in the house. I opened the T&P valve and this also discharged rusty water for a couple of seconds before the water became clear.

There is no problem with the cold water. My previous water heater did not have this problem. I have city water supply, no softener, set to 120 degrees.

I read that corrosion can occur at the hot water outlet if a dielectric union is not used with copper pipes, but my condo has CPVC pipes so I'm thinking that should not be an issue for me? Also not sure where rusty water coming out the T&P valve fits into the equation.

Would corrosion inside the heater tank body occur this quickly (in a week or less) - isn't the anode rod supposed to reduce this, at least at first? Maybe a short or stray current in the new water heater is causing corrosion this quickly?

So, not sure what to do or who to call next. Maybe call the handyman who installed the heater and have him check the connections for corrosion even though I do not have copper pipes? Maybe call Whirlpool and see if they will replace the heater and hope that this heater was the problem and the new one will work properly?

Attached some pics - the expansion tank is about 6 years old - used on old heater without issues. Installer checked it and did not feel that it had to be replaced.