Hello All, This is my first post here on the forum. I have spent many long hours searching the internet for assistance on the installation of this tankless heater. I am replacing a conventional natural gas 50 gallon heater with the Paloma PHH-32 Condensing series tankless. The new heater is .90 % + efficient and vents with 3" PVC. My installation is such that I am planning to use the existing roof jack/penetration in my roof from the old heater to vent the new tankless heater. The Paloma has two pipes. One is the 3" Air Intake, The other is the 3" exhaust. I purchased the PVC Vertical Concentric termination Vent pipe kit so I could combine both the exhaust and air intake pipes into one roof penetration. My question is this: My installation will be Straight up Vertical with the two 3" Pvc conduits, Up thru the heater closet and then straight up thru the roof. I could not get a clear answer from Rheem whether this is ok. The manual mentions a condensate trap on a horizontal run of the air intake. Can I run my vent system straight up or do I need to actually create a horizontal section for the trap. Also on the Concentric termination vent that goes thru the roof there is no rain cap or cover on the exhaust vent. That means rain water will spill into the heater. How do I correct this or is rain water entry allowed into the exhaust?. I really want to do this installation right the first time and I appreciate everyones assistance. I would look forward to your comments. Thanks!!