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The usual way to shower in an RV involves shutting off the water a few times, so most RV shower heads these days include a shut-off. This would be a great idea if it weren’t for two things:
- The shut-offs usually leak horribly.
- Typically, you get frozen or scalded when turning the water back on.
In our RV, we were getting frozen out by the shower head shut-off, so I finally decided to do something about it. This video is the result:
The problem here is something called “crossflow”. Crossflow can occur when you open the hot and cold water taps, and connect them together. This is what happens in a shower head, where you allow the water to mix, and then shut it off someplace after that. This will allow the water to flow from cold to hot, or hot to cold.
Which way the water will flow depends on whether your hot or cold water was at the higher pressure. In our RV, the cold water was at a (significantly) higher pressure than the hot water. This was allowing the cold water to push its way back down the hot water piping – leaving us with nothing but cold water when we turned the shower head back on.
Now if the hot water was at a greater pressure than the cold, you could have the reverse situation happen. This would leave you with nothing but hot water in the shower and plumbing lines, and could potentially scald you. That would be bad! I’ve not found a definitive source on this (I’m sure someone will correct me in the comments if there is one), but the theory is that shower head manufacturers are guarding us against such a scalding by building shower heads that leak – on purpose – when the shut off is engaged.
That’s a cute idea and all. But it doesn’t actually work, and just wastes water.
I started off just trying to fix the cold water, but later realized I needed to fix the leaking as well to solve the whole problem. So I wound up installing a check valve (on the hot water, to keep the cold from working its way down that line), and also a shower shut off valve that actually worked. (Most shower shut-offs that you’ll find also exhibit the leaking).
If you want to play along in your own RV, here are the key parts I used:
And if you have a Winnebago Travato 59G like we do, you’ll also need to order this gasket:
Beyond that, the video is pretty self-explanatory. One word of caution though: Since we are talking here about defeating a reputed safety feature, be sure you know what you’re doing! If, for example, your hot water was at a greater pressure than the cold, you would have to move the check valve to the cold water piping, or you would scald yourself. If the above doesn’t make sense to you, I’d recommend you don’t try this yourself, and instead, consult a plumbing or RV service professional. I don’t want to be responsible for anyone getting scalded!
I’m happy to report that after these additions, our shower stays at a constant temperature when the flow is shut off. The leaking has stopped as well! Hopefully, this helps some of you out, too.