Ya I tend to do that when playing with wiring. But the way the timer function/time cycles are setup via 2 extra wires and again lack of access kinda led me there. Plus I always see one more switch or function if I just...
Had I placed the momentary (or on/off) switch in a more easily accessible place I likely wouldn't have added timer.
Our bath sink and water heater are at opposite ends of camper. Pump runs for 10 seconds until hot reaches bath sink then pump shuts off. So very little actual hot water is being pumped into the cold line. Though I don't know that what little may being detrimental? I haven't noticed hot at bath sink cold side so I assume its pushing back toward heater.
But yes if left on longer than needed it could fill all the cold lines with hot. But this only runs for a few seconds until hot reaches faucet, instead of turning on tap and watching water run down the drain until it becomes hot.
I honestly didn't know if this would work. Simple $35 experiment verified it does. The only thing I would (and will) do different is a better pump plumbed with flex lines.
Pump has only been in a month but 2 short outings, so far its worked well. For what I have in it happy. As far source, I looked at what others had done but it was after installing the one in our home 3 years ago that I kept going back to. Its what I copied. Same principal, simple pump spliced between hot and cold at bath faucet.
