Here are a few images of the most simple yet so profoundly efficient cabin hot water system.
This convection system operates on the principal that hot water rises. The stainless steal tank is fed with cold water at the bottom end (not visible). The tank connects to the stove via a copper line that is attached to a 2 inch diameter U-shape metal pipe, which heats the water as a fire is going in the stove. The heated water rises to the top of the tank. As a tab (sink or shower) is opened the drop in pressure powers a Jabsco in-line pump and delivers water. The now utilized water is instantly replaced through a 55 gal reservoir that is the "feeder" of the entire system (not visible).
This is what you can't see: Through a T-fitting right after the "feeder" reservoir cold water can be obtained thus allowing the user to mix to the desired temperature. The hot water tank (in this case the stainless steal tank), MUST have a pressure release valve at the top end, dumping the hot water safely, should it ever come on. This tank also has a drain valve at the lowest point.
Talk about luxury! Taking a shower at 50 below, or 50 above for that matter. Best of all, hot water will always be available, as one tends to have a fire in the wood burning stove anyways. A win-win situation, if there ever was one.
Logging off, taking a shower now...