Understanding Difference Between Hubs and Spigots for RV Waste Valves

Question:

My question on which of the Valterra wye assemblies to choose is similar to that of Dave B, who was trying to compare the TR38, TR38A, and TR38B I believe, but it has a more basic question I must first answer. I live in my 1997 Coachmen Catalina 299TB, and when I could no longer operate my black water waste valve, resorted to leaving it open while I waited for money to replace the valve. I bought the valve and installed it, I think correctly, but it seems that my old wye has been kicked or stepped on since then and is broken. This is my first plumbing job ever. I think I need the TR38, but in identifying the hubs and spigots, I am too unfamiliar with ABS plumbing to know what Im looking at. Here are photos of the plumbing as it sits. The photos may not be good enough to use for identification, but my plumber friend is out of town for a month and I have no one else I can ask. Thanks in advance! By the way, I had to combine my two photos as your site wouldnt allow me to upload a second image.

asked by: Terri K

Expert Reply:

You should be able to tell which Valterra Double RV Waste Valves you need by inspecting your current connection points. The one end with the lugs on it is the same on all 3 parts so you simply need to determine if you need hubs, spigots, or a combination of both.

A hub connection fits around the spigot so you just need to check the other side of your waste valves to see if the adapter has fittings that connect on the inside or outside of the pipe they are connected to. Then you just need to choose from the following options:

3" Hub/1-1/2" Spigot - # TR38
3" Spigot/1-1/2" Hub - # TR38A
3" Spigot/1-1/2" Spigot - # TR38B

To me it looks like you need the part # TR38A which is the 3" Spigot/1-1/2" Hub but it's hard to see totally in your picture. If the smaller valve fits around the pipe of your trailer and the 3 inch into the pipe then this is what you'd need.