I recently installed a Takagi Flash TK-jr tankless water heater. Let
me first say that I absolutely love it, it performs flawlessly, and
I've already seen a decrease in my gas bill.

That said, I removed the old tank unit and drain pan, and I did
install a pressure relief valve on the new unit, complete with 3/4"
copper drain line. The old copper drain line emptied into the pan,
but it seems like a complete waste to install a huge round drain pan
under this new, very small, tankless unit.

The UPC requires a watertight pan in attics, where it is, with a
minimum 3/4" drain that terminates to the outside.

My question is.... what have others done for the tankless units?
What kind of drain pan arrangement have you used?