A couple issues have been bothering me since the weather turned cold and they are:
1) Running the hot to get the shower ready wastes water. It takes a couple quarts to drain the cold out of the line and get the water hot at the shower head. I’d like to recapture that water and keep it fresh
2) Once the temp drops below 10ºF the lines in the coach begin to freeze. The water lines to the bathroom run outside the heated space for a few feet and they freeze around 10º. The water pick-up from the fresh water tank is below the tank, running between the tank and the insulating skin on the bottom of the coach. That line freezes around 4ºF
My previous coach was good to -30ºF and I would like to come closer to that operating ability than I am now. One way to do that would be to remove the bottom skin and re-plumb the coach, add insulation, etc, but for now I’m going to create a plumbing circuit that will address both issues.
If there is a flow of water it has to get a lot colder before it will freeze. Running streams don’t freeze as soon as still water so I built a water return circuit to get the hot water from near the shower faucet back to the fresh water tank.
I tapped into the hot water line near the shower with a custom made T- fitting then ran a 3/8” line to a ball valve in a place accessible from inside the coach. From the valve I ran the new water line forward through the cabinetry to the fresh water fill port. I tapped into the 1/2” vent line to the tank and connected the new water line to that.
Now when I open the re-circulation valve the fresh water pump pushes water to the water heater, then to the shower, then at the T it flows to the valve (open position) then back to the fresh tank via the vent line.
This keeps hot/warm water in the hot line all the time that the valve is open heating the pipe space and keeping the hot and cold lines from freezing. It also keeps water flowing through the fresh pick-up line (keeping it from freezing) and adds hot/warm water to the fresh water tank keeping that tank a lot warmer.
This system does required a 110V connection to keep the water pump supplied with power and to keep the water heater running on 110V. It would also work with the gas water heater system and enough 12V power to run the water pump 50% of the time.
If the re-circulation valve is opened just a tiny bit the water flows and the pump cycles on and off, running less than 50% of the time. The coach has an accumulator/ expansion tank on it to cut down on pump run-time.
When it’s not super-cold outside the re-circulation valve is only opened before I jump in the shower. It flushes the cold water out of the line and pumps it back into the fresh tank so I have hot water right away in the shower.
Since I’m in warm and sunny* California for the next few weeks I won’t have a chance to test the cold weather capabilities of the new system, but the shower pre-heat part works great!
Project Update! It’s October 2019 now and I finally had a chance to test the non-freeze properties of my plumbing project. It got into the single digits last night and I set the water to trickle and it kept the hot and cold pipes toasty warm. The pump cycled every 25 seconds and that was enough hot water to keep it all flowing. YaY!
*. By warm and sunny I mean 50ºF and raining a fair amount. It is however so much warmer than the -2ºF I drove thru to get here