After a couple hours of AC operation should there be any water in the secondary pan?
It seems to me there would be a steady volume of water coming off of the coils and not a surge of water, causing it to overflow into the secondary pan.
you have a stoppage or leak
Should not be any water in pan. Make sure your condensation line is routed properly with no reverse slopes. Sounds like a possible airlock in the line to me.
I now believe there is a leak in the pan. Would you share some of your experiences of where in the pan it might be leaking? I am pretty darn sure the coil box has been mounted with an appropriate angle. Thank you for your help.
The pan is placed below the air handler to catch an overflow of the condensation in the air handler. There should never be any water in it. If there is water in the pan something is not right. Any water that does collect in the pan would exit via an overflow tube (call it a SECONDARY drain)which should be outside in some area you would notice it. If you see water from this pipe it needs to be addressed.
The "angle" I was refering to is your PRIMARY DRAIN LINE. If it is plugged up (it does happen) or is not routed correctly it will cause an overflow into the pan. If the pan is leaking that needs to be corrected also, but you need to discover the reason for the overflow in the first place.