Just finished putting in a new countertop and sink in my kitchen in a older single wide.
While redoing the countertop I placed some scrap Hardie board on
Two sides and the above the electric water heater that is placed below
Corner of my "countertop" to help keep the "Heat"
That was coming from the water heater out of the kitchen and block some
Outside air from being drawn into the living area from the outside access panel.
The Hardie board only covers the one side and the back part of the water heater
Towards the utensils drawers, not towards the sink.
Now I have a problem with my "Cold Water" being very warm going to the sink
And the bathroom faucet that goes in the other direction from the water heater.
I put some foam aroung the c-pvc tubing in the water heater space/box, but it didn't help.
Short of moving the water heater what can I do to resolve this problem?

Thanks for any tips or ideas!!

Does that cold supply line past through this insulated box you made with Hardiebacker?

Install heat trap nipples on the water heater. These will keep the hot water from migratating up into the cold supply line.