How To Install RV Water Heater 3-Way Bypass Valve

Updated 10/21/2025 | Published 09/25/2020

Question:

Do you have a three way valve that lets you attach the 1/2 female npt to the hot water tank inlets and outlets, instead of screwing the male npt into the tank?? My tank has about a 2 inch male nipple coming out of the tank which is what I would like to attach to with a female npt, and have a male npt on the outside of the three way valve to reattach my water lines to. It seems to me that all your valves you sell are reversed of this orientation and seem the be backwards for my application. Why are all these made that way when most tanks have a male fitting to attach the supply lines to. It defeats the purpose of the three way valve if you need couplers and nipples to make this work properly. Am I misreading your info on this that the flow is bypassed through the female port and out through the side port?? If so it would need to bypass through the two male ports and shut off the female port to work on my RV. I do not get it why these are made like this, seems backwards to me. Can you help me if I am thinking this wrong...

asked by: Keith H

Expert Reply:

I have attached a photo below which shows the proper installation of a three way water heater bypass valve kit like the Camco RV Winterization Bypass Kit part # CAM35953. The female fitting on the bypass attaches to a male fitting on the water heater. The other two male fittings on the bypass then attach to the hoses.

expert reply by: Conner L

click to enlarge

Adam

10/19/2025

Hi Conner. I believe Keith is correct. When installing the female NPT port on these fittings to a water heaters male NPT outlets, the water heater will fill with antifreeze when the bypass valve is set to bypass. A video on Camco's website even shows a male fitting on these valves attached to female fittings on a water heater.

Kate F.

10/21/2025

@Adam You’re absolutely right that the female NPT ports on the bypass valve connect directly to the water heater’s male NPT fittings, that’s exactly how Camco’s setup is shown in their video and in the diagram Connor shared. However, when the bypass valve is set to “bypass,” the water (or antifreeze) should flow around the water heater, not into it. If antifreeze is filling the tank during bypass, that usually points to one of two things: - The valve isn’t fully turned to the bypass position, or - There’s a failed or missing check valve on the hot water outlet of the heater that’s allowing backflow. So the threading and installation you described are correct, but in normal operation, the bypass mode should prevent antifreeze from entering the heater.