RV Engineer shows how to fix the RV shower cold blast that comes from switching the shower on and off. Done a Grand Design 311BHS 5ther 5ver fifth wheel
Know why the pipe threads leaked? Because the faucet uses NPS threads (national pipe straight) and the back flow valve is NPT (national pipe taper). Both share the same thread pitch. While NPT & NPS threads will engage and seem like they fit - they will not seal properly with each other causing leaks. Sure you thought you solved the leak by going all out on pipe tape but really that was not the answer. You needed to cut the red pex hot pipe along the vetical section of pipe very close to the 90 degree elbow and used a 1/2" pex barb to 1/2" MNPT (male NPT), and a 1/2" pex barb 10 1/2" FNPT )female NPT and the back flow valve goes between the MNPT and FNPT. As for NPS straight threads they seal with a rubber cone inside the threaded nut whereas NPT seals by wedging the threads together and pipe tape helps ensure a good seal as well act as a lubricant to allow those tapered threads to bind together tighter.
My general answer would be no. If you winterize per Grand Designs instructions, you are running glycol through your plumbing system until flows out the nozzle, so you have the glycol from the pump through the backflow preventer. If you winterize by only blowing air, I again think it would be fine, you'd just probably want to make certain you only have that line open so that there is enough pressure to evacuate the line and overcome the internal spring inside the backflow preventer. I haven't had any leaks or issues from winterizing with it.
Know why the pipe threads leaked? Because the faucet uses NPS threads (national pipe straight) and the back flow valve is NPT (national pipe taper). Both share the same thread pitch. While NPT & NPS threads will engage and seem like they fit - they will not seal properly with each other causing leaks. Sure you thought you solved the leak by going all out on pipe tape but really that was not the answer. You needed to cut the red pex hot pipe along the vetical section of pipe very close to the 90 degree elbow and used a 1/2" pex barb to 1/2" MNPT (male NPT), and a 1/2" pex barb 10 1/2" FNPT )female NPT and the back flow valve goes between the MNPT and FNPT. As for NPS straight threads they seal with a rubber cone inside the threaded nut whereas NPT seals by wedging the threads together and pipe tape helps ensure a good seal as well act as a lubricant to allow those tapered threads to bind together tighter.
I fixed my cold blast. I like my showers much better now.
Thanks for the video! I have to get one of those. Is your RV a 311BHS by chance? It looks very similar to ours.
Yes, it’s a 2020.5 311BHS. Very easy on that model.
@@rvengineer2300 Great. Mine is a "2021" but I don't think that means anything LOL
Would a back-flow preventer cause problems when it’s time to winterize?
My general answer would be no. If you winterize per Grand Designs instructions, you are running glycol through your plumbing system until flows out the nozzle, so you have the glycol from the pump through the backflow preventer. If you winterize by only blowing air, I again think it would be fine, you'd just probably want to make certain you only have that line open so that there is enough pressure to evacuate the line and overcome the internal spring inside the backflow preventer. I haven't had any leaks or issues from winterizing with it.
Do you have a part number or a link for this part? I want to add a couple on my 2019 GD Reflection 28bh.
Here’s the one I used:
Camco 23303 1/2" Back-Flow... www.amazon.com/dp/B000EDUTN6?ref=ppx_pop_mob_ap_share