0. This wasn't my idea. I stole it from http://www.modmyrv.com/2009/06/10/rv...er-accumulator
and made some slight mods to simplify it. For example, the original uses a number of bushings to reduce down to the final water connection. Also the schrader valve in the original is a gasket-style seal. I chose to drill and tap threads into the PVC and seal with joint compound. It made for a more compact design. My thought is that any water that is left inside below the water line connector is not enough to fracture the tank due to freezing. We'll see.
1. Total cost for the tank was $20, but the other plumbing (which would be required for installation of a commercial accumulator tank) cost about $10. The tank was made out of a 10" long section of 4" PVC schedule 40 (2L capacity, not counting the end caps).
2. The installation with PEX was a snap. I cut into the cold water feed to the hot water tank and installed in that compartment. The final connection is made with reinforced flexible water line for forgiveness on final tank placement. On the X23B, it's forward under the port side dinette seat.
3. The tank is secured in the compartment with a couple of hose clamps that are screwed into a reinforced compartment side.
4. With the pump on and accumulator shut off, I can get 2oz of water out of the lines before the pump activates. With the accumulator turned on, I get 6oz of water. So it's running 3x less often which should be good for the motor pressure switch.
5. With the pump off and accumulator shut off, I can get 1 liter of water out of the lines. With the accumulator turned on, I get 3 liters.
6. There is no more "pulsing" in water flow when the pump turns on and off. I get a perfectly steady stream, even when just using a trickle to brush my teeth. I think a smaller accumulator would have probably had the same water smoothing effect as the large one that I built.
Of course I'm super excited because I built it myself.