This stems from a brilliant project posted by SteveAE over on the boondocking forum, to keep the tank from freezing. His project involved a solenoid that controlled the flow of hot water into the outlet pipe of the tank.My idea is much more crude (and much easier for the non-technical person). Imagine a tee coming off the hot water line that runs to the sink. Imagine a hand-controlled valve at that tee. From the tee, run a line to the cold water intake filler pipe, which is just a gravity feed tube down to the tank.In the late evening on a cold night, turn on the water heater (if it is not already on). Once the water is hot, open the valve at the tee and run several gallons of hot water into the fresh water tank. (The tank should be insulated -- I have reflectix over it, but I think I will add more insulation.)This crude solution warms the tank. The downside is that it is a one-shot deal before bedtime -- nobody is going to get up and do this in the middle of the night. Steve's solution is temperature-controlled -- no human needs to lift a finger.So that is my question -- what do you think of this amateurish work-around? I wanted to get your thoughts, both pro and con, before I cut into my water lines!Obviously, this is not going to work for sub-zero temps -- the tank will freeze no matter what. But we have discovered that our water lines don't freeze in the 20 degree range, although they will freeze at 11 degrees. Please don't ask how I discovered this threshold.I look forward to your comments!(By the way, this is for boondocking -- if we had hookups, I would just install heat tape and be done with it.)

How about the theory that cooling hot water freezes quicker than cooling cold water?

Should work fine. Could let the water heater cycle a few times to prepare for a very cold night.No shortage of propane right?Could just get a hose adapter for a faucet and run the water direct to the normal fill point. $6 or less for proof of concept.http://www.homedepot.com/s/faucet+to+hose+adapter?NCNI-5

WyoTraveler wrote:How about the theory that cooling hot water freezes quicker than cooling cold water?That theory has been proven to be bogus. It is true that hot water initially loses heat faster than cold water, because the rate of heat loss depends on the temperature differential between the water and its surroundings. BUT the hot water still has much more total heat to lose before it gets down to the same temp as its surroundings, so it is less likely than the cold water to freeze in the same amount of time.I think this is a good simple idea and wouldn't cost much to try out.The lines & pump will be full of warm water. Plus the warm water in the tank will radiate some heat into the area of the pump uptake line. If you could wrap Reflectix all around the tank & uptake line, that would be helpful. (I'm assuming you are talking about an exterior tank with an uptake line to the pump inside the trailer.)

WyoTraveler wrote:How about the theory that cooling hot water freezes quicker than cooling cold water?that is true for systems where evaporation helps to cool the water faster than just conduction and radiation losses. as hot vapor leaves the surface of the water, it takes heat with it... so hot water in the ice cube tray freezes faster than cold, but only a little.rv plumbing system is a closed loop more or less, I guess you would have some evap in the holding tank, but OP states the tank is insulated, so the heat would be retained in the air inside the tank and not lost from the system completely.

That manual valve would be nice when boondocking to preheat the water lines--so there would be less waste water. Go for it!

Idea for simplified water tank heating -- need your advice

WyoTraveler
Explorer
Nov 22, 2015
How about the theory that cooling hot water freezes quicker than cooling cold water?
time2roll
Nomad
Nov 22, 2015
Should work fine. Could let the water heater cycle a few times to prepare for a very cold night.
No shortage of propane right?

Could just get a hose adapter for a faucet and run the water direct to the normal fill point. $6 or less for proof of concept.

http://www.homedepot.com/s/faucet+to+hose+adapter?NCNI-5
coolmom42
Explorer II
Nov 22, 2015
WyoTraveler wrote:
How about the theory that cooling hot water freezes quicker than cooling cold water?

That theory has been proven to be bogus.

It is true that hot water initially loses heat faster than cold water, because the rate of heat loss depends on the temperature differential between the water and its surroundings. BUT the hot water still has much more total heat to lose before it gets down to the same temp as its surroundings, so it is less likely than the cold water to freeze in the same amount of time.

I think this is a good simple idea and wouldn't cost much to try out.

The lines & pump will be full of warm water. Plus the warm water in the tank will radiate some heat into the area of the pump uptake line. If you could wrap Reflectix all around the tank & uptake line, that would be helpful. (I'm assuming you are talking about an exterior tank with an uptake line to the pump inside the trailer.)
GordonThree
Explorer
Nov 22, 2015
WyoTraveler wrote:
How about the theory that cooling hot water freezes quicker than cooling cold water?

that is true for systems where evaporation helps to cool the water faster than just conduction and radiation losses. as hot vapor leaves the surface of the water, it takes heat with it... so hot water in the ice cube tray freezes faster than cold, but only a little.

rv plumbing system is a closed loop more or less, I guess you would have some evap in the holding tank, but OP states the tank is insulated, so the heat would be retained in the air inside the tank and not lost from the system completely.
pianotuna
Nomad III
Nov 22, 2015
That manual valve would be nice when boondocking to preheat the water lines--so there would be less waste water. Go for it!
profdant139
Explorer II
Nov 22, 2015
I really like SmKettner's idea -- hook up to the faucet and run an ordinary hose into the fill pipe! The only trick is how to get the hose from the faucet inside the trailer into the fill pipe, which is outside.

Hmmm. I have a connection for an outside shower, which I do not use (and have disconnected). I wonder if I could use that as the source of the hot water, since the source is already outside?? I could simply run a hose from the outside shower faucet to the water fill pipe -- very simple.

But that would probably mean that I would have to go outside just around bedtime to turn on the hot water, and then go back out there to turn it off a few minutes later. In 15 degree weather. Possible, but not wonderful.

So back to the idea of running a pipe from the faucet to the fill pipe -- I guess the tee into the fill pipe would have to be inside the trailer.

Keep those ideas coming!!
DrewE
Explorer II
Nov 22, 2015
WyoTraveler wrote:
How about the theory that cooling hot water freezes quicker than cooling cold water?

It's wrong. If you think it over, you'll realize that before it becomes frozen water, the hot water has to first become cold water...at which point it takes as long to freeze as cold water.

Likewise, hot water comes to a boil sooner than cold water, for exactly the same reason.
WyoTraveler
Explorer
Nov 22, 2015
DrewE wrote:
WyoTraveler wrote:
How about the theory that cooling hot water freezes quicker than cooling cold water?

It's wrong. If you think it over, you'll realize that before it becomes frozen water, the hot water has to first become cold water...at which point it takes as long to freeze as cold water.

Likewise, hot water comes to a boil sooner than cold water, for exactly the same reason.

Gordon three post covered it very well. But for your information it is called the Mpemba effect dicovered in 1963
Acampingwewillg
Explorer II
Nov 22, 2015
Just a thought also...I know my water heater has a pressure release valve on the same side of the MH as the water fill....just wondering if you could use that as your source of Hot water for mixing?
profdant139
Explorer II
Nov 22, 2015
Acamping, I thought about the pressure valve -- run a hose from that to the fill pipe -- but that would mean I would have to go outside in the freezing cold to push down the little lever, right before bedtime. Brrrr. Maybe I could rig up a little stick to push the lever with, from inside . . . . ;)

Forum Discussion

Idea for simplified water tank heating -- need your advice

About DIY Maintenance

Related Content

Downsizing and simplifying

Time to downsize, Time to simplify

Aqua Hot heating system & overall advice 2009 Monaco

Electric heating

heat ideas