Dangerous Experiments

WilliamA

There are many ways to calculate data, but without failure testing, data is mostly useless. Unless one tests to failure, there isn't any way to know what that point is.

To that end, I've been running an experiment to see at what point the plumbing in my trailer freezes. This is something I have wanted to determine since I got the trailer, but now that I am re-plumbing it anyway, it's the best time to find out a few things:

1. At what point does the plumbing freeze.

2. Where does it start to freeze and what happens first.

3. How much freezing can it take before failure.

I'm relatively unconcerned with the water tank freezing as it's a huge mass and doubtful it would freeze enough to damage until long after the small bits have failed. Living in Wi, there's no end to the opportunity to apply cold. This morning, the temp was 17 degrees with 3 inches of new snow. No problem.

I filled the water tank and turned the electric furnace down to 50 overnight. Since the inside temp was around that, and the water tank is mostly in the heated space beneath the mattresses I had a good baseline. This morning, the kitchen hatch was iced over and the hatch was frozen in place. I worked for a bit to free it, opened the hatch and the water tank was liquid but the plumbing was frozen. The pump would run, but the water would dribble out the tap for a few seconds, then stop. I heated up various components with the hair dryer until I got water to flow and worked out where the most ice was. Unsurprisingly, the hardest frozen spot was the water line where it comes out of the tank and goes to the dump valve. A bit of heat there and the pump started providing some consistent flow. I am running the diesel heater now to heat up the plumbing closet and get things back up to safe temp and will then examine all of the plumbing to include disassembling the pump to check for damage. I'll report my findings when that's all done but consider the whole thing to be entirely satisfactory and unsurprising. It will guide my selection of valves and hose as I replace the plumbing and also give me better data for where to put the dump valve. Obviously, that exposed bit is where it started freezing first so that will need to be moved....

Back to work...

WilliamA

Frogger

Did you make that awning? Pretty neat...

WilliamA

https://teardrop-trailers.vanillacommunity.com/discussion/comment/7396#Comment_7396

I did! Thanks! I can say after a year of testing that it works great and is proving to be a great asset! There's a thread on it here somewhere. Finish cost for material was under $250.

Snow load!

WilliamA

WilliamA

Lots to share after a day of heavy duty putzing. I'll be posting updates on a couple of different threads.

WilliamA

ontheroad

We reached 17* F in Texas in January..no water onboard....and our galley never froze...luckily..gotta make that morning Java! Won't talk about the water jugs I left out...

WilliamA

Well this has all been interesting. A couple of things I learned: from my rude, crude tests, it "appears" as though the water line that comes from the tank to the pump is the first thing to freeze. The next is the line from the pump to the faucet. I suspect that all of the lines will freeze in close succession, but I believe the feed line is the first ( this is anecdotal at best) because it has the drain valve and associated through-hull opening. That makes sense and confirms a suspicion I had. For my re-plumbing job, I am going to eliminate the tank drain. This is for two reasons: The first is to eliminate the hole and tubing coming out of the trailer. The second, (and unrelated to freezing,) is that whenever I empty the tank, I just use the pump. The drain valve is piddly, takes hours and doesn't completely drain the tank. By pumping it out through the faucet, I can drain the tank completely down to a few ounces in just a few minutes.

The next order of business is the pump. I like the stock pump as it seems to be robust and able to handle my abuse without problems. The few problems I've had appear during spring "startup". First, there is no provision for priming it. I am going to add a priming port to the inlet side to do that. I did find a field-priming technique that (sort of) works. I take the inlet line off of the pump, then attach the line off of the shower assembly to the inlet. By opening the valve for the shower, I can then pour water into the "city water" port and prime the pump. I tried doing that by connecting the hose and turning on the water hose, but it's obvious that the pump does NOT like pressure on the input side as it unseats one or more of the diaphragms within the pump. I've had that happen twice, requiring complete disassembly of the pump to reseat the check valves. Trying to gravity-feed water into the city water port (it's angled down) is problematic, so I'll just add a priming port and valve to gravity feed water into the input side of the pump.

Now, to the pump. I don't use antifreeze in my water system and just drain it down for winter. Once it's drained aown, I remove the outlet line and run the pump for a few seconds to clear out any remaining water in the valve Chambers. This seems to be problematic as the valves (diaphragms) dry out and tend to "stick", making it difficult to get things going again in the spring. There are 10 diaphragms inside the pump. 4 in and 4 out for the pump, one small diaphragm for (I suspect) a pressure relief, and one for the pressure switch. It seems to be a good pump and much better for this application than a cane pump. This kind of pump can be run dry without any problems where a cane pump would quickly be ruined. The problem is all of those rubber valves. They tend to stick when they are dry. It's not a problem as just a gentle poke with a finger frees them up again, but you have to completely disassemble the pump to do it. As I said above, pressurising the inlet side is NOT a good option. I have experimented with. Pressurizing the tank at very low pressure ( under 3 psi) to coax water up to the pump inlet and that works, but if a diaphragm is sticking, it's unlikely the water pressure will unseat it. Once I put a priming line in, I will try running RV antifreeze through the pump, thus leaving the pump internals "wet" for winter. That should solve the sticky valves.

I also am cogitating the idea of moving the pump from the wall down onto the floor where it will gravity feed. I'll experiment with it....

Anyway, I've concluded the experiment and things don't seem to be the worse for wear. I put everything back in order, ran the system for a bit and then pumped the tank dry to wait (again) for better weather. If I get bored, perhaps I'll post a thread on how to disassemble the pump (it's easy) and what to poke at to get it working.

WilliamA

WilliamA

More danger. Got around to installing the rotopax kit...

More mayhem to come.

Just a couple more things now...

WilliamA