Hello recently my old 50gal gas water heater developed a crack and started leaking. I replaced it with a tank-less gas heater. Everything is good, I installed the proper intake an exhaust with 3in schedule 40 PVC pipes as recommended, I plumbed 3/4in copper pipes for cold and hot water, a 3/4in gas line. I now need to connect the pressure release valve. I have a 3/4in copper pipe plumbed into the house drain close by, so it does not look to be a big deal, however, this unit also has a condensate drain. Right now I have a temporary 1/2in PVC discharge into a bowl, but I plan to install a condensate neutralizer (it's arriving tomorrow). However where am I going to drain the neutralized water? Can I plumb it with the relief valve? Eventually it will have to go in the drain anyway. The unit is installed in the center of the house upstairs in an utility room.
Make sure you pipe your pressure relief valve down to within 6" of the floor and not into the drain maintaining 3/4 inch diameter all the way. In the rare event that it pops you are supposed to see the water on the floor and thus be alerted to the issue. If it's down the drain you will never know you have an issue. 
