It could be a faulty appliance. I would start by unplugging everything I could. Shut off the hot water heater and refer. Then try it. It could be the heating element in the refer or hot water heater.
The GFI trips because of a faulty grounding situation, not an overload.
If it still trips the power distribution panel may not be wired correctly. The white (neutral) and green (ground) wires should Not be hooked together. I have seen that on other units.
Might get an electrician to help you if you are not experienced.
You may call me if you wish.
I am an electrical troubleshooter.