Originally Posted by DanyaScavo
Thank you so much for your input! I think we figured it out with your help! The water system has three different places that have valves to open. We do have the outside shower, and hot water was coming out lukewarm there as well. I'd never used it before and have only showered in the RV shower a handful of times (we have a great shower house at our resort we've been at since August). The hot water valve that's listed in the schematics to be for the outdoor shower is apparently also linked to the indoor shower.
We bought the RV new and had it winterized feb-may this year. Only took me 7 months to realize the water wasn't hot enough. Haha.
There is actually no valve in the schematics for the outdoor shower or indoor shower. The valves all pertain to the water heater and the hot water or cold water lines.....and being able to winterize the water lines without having to use six gallons or more of antifreeze in the water heater.
If you will look at the schematic(s), for normal use the inlet valve to the water heater is open. This allows cold water into the water heater.
Now the outlet valve is open, which allows hot water out of the heater (once it's heated to temperature), and this goes to your hot water taps when turned on. Works just like the water heater at your house.
You will notice that there is a water line before the water heater that connects the cold water line to the hot water line. This is the true bypass valve. For normal use, you have this valve closed, so that cold water will not be mixing into the hot water line. Most likely your problem, is this valve is either open or partially open...which is causing you to get cold water mixed into your hot water line while showering or using anything that requires you turning on the hot water tap. You are getting cold water into the hot water line via the bypass valve not being fully closed.
Now, you may be wondering why is there a bypass valve to start with. Well, when you go to winterize your water lines, you may want to put special RV water antifreeze in them to keep them from freezing up and bursting during the winter months.
So how do you get antifreeze into the hot water lines? What you do is use your water pump and there is a suction valve usually near it, that let's you suck antifreeze into the cold water line while the pump is running.
Now, in order for the hot water line to get antifreeze in it, it would require the water heater to first fill full of antifreeze before it could get into the hot water lines (cold water in, hot water out). That's a lot of antifreeze at $5-10 per gallon.
Here is where the bypass valve(s) work. You close the valve that allows cold water in, and you close the valve that allows hot water out of the heater. Now the water heater is closed off from antifreeze being able to get into it from the cold water inlet line, or backflowing into it from the hot water outlet line. The water heater is BYPASSED.
You now OPEN the bypass valve that connects the cold water line to the hot water line. This allows antifreeze that is being pumped into the cold water line, into the hot water lines...thus filling them with antifreeze to protect them also from freezing.....and not wasting any in filling up the water heater......which you are supposed to drain and it won't have any water in it to freeze (or very very little).
What happens when you leave the outdoor shower taps on, but shut off at the head, is real similar to the bypass valve. It allows cold water to be sucked into the hot water line via the shower wand head. once the hot water taps are turned on elsewhere. That's why you want to make sure you turn the outdoor shower taps themselves off, and not just the wand.
This schematic may help in the understanding of that.