Posted on 12/23/2022 10:19:59 PM PST by Paul R.
Can supercooled running water freeze due to a pressure change?
Thursday I spent almost all day prepping for our "Arctic blast" that rolled in late in the afternoon. (Most impressive!) Among many other things, I checked to make sure the small thermostatically controlled heating element under our water tank was plugged in. (The wellhouse is part of but outside our house proper.) I ended up getting to sleep around 2 am -- exhausted & filthy I just crashed out on the carpet in the LR. (With all my warm clothes on it was quite comfy.)
I woke up ~8 am: Restroom!! Water (drip) running? Great! Outside temp on our back porch? -9 F, and still windy. Check the chicken house -- those birds may be dumb, but they are still all inside... Plenty of food still in feeders. I should be inside too and take my own advice...
Really should clean up! Fire up the in-wall heater in the bathroom (tends to get chilly in there overnight). Accelerate process by starting shower on "hot". Brush teeth. I'm almost done with the tooth brushing - water running @ sink too, total GPM probably ~ 2-2.5 gpm, and... the water slows and dies. What???!!!
Put dirty clothes back on, go investigate. Well pump gauge shows 38 lbs. pressure. (It kicks on around 35 psi or so. Pump has power. The pipes seem intact, but the electrical warming wrap feels cold - must have failed. The heating element under the tank is warm, but tank is still darn cool.
I get a small fan type space heater & set it up to blow warm air on the pipes. 10(?) minutes later, we have running water again, pipes are all ok. WHEW!
Take that shower / bath and warm my cold bones!
Best I can figure is that the water in the well (pressure) tank was nearly(?) supercooled and at ~45 psi (where it'd top out when refilling). Exiting the tank, the pipes would have been even colder, and there'd be some pressure decrease down the length of pipe (plus tank pressure was falling). Somehow, significant flow (as opposed to the drip) triggered an abrupt freeze-up. Could the pressure drop do that?
Tomorrow's project: Dig in and fully check out that heat tape! (I don't like leaving a space heater, even on low, running out there. It's overkill and a little unsafe. Granted a 100 watt incandescent light bulb will work, but, I'm low on those, and would need thermostatic control of such, too....
Good Luck and Merry Christmas!
Looks like you are working through the problem.
Keep us informed of your progress and steps to resolution.
Interesting problem!
Ever leave a bottle of pop in the freezer to get cold, you take it out and does not look to be frozen, untill you pop the cap then it instantly freezes. Same theory. Liquid under pressure has a lower freezing point, when pressure is released, liquid will freeze.
I seem to vaguely recall that a fluid in motion has lower pressure, too.
You have chickens, so use a brooder lamp.
>> Can supercooled running water freeze due to a pressure change?
You’d be long dead before water is affected by pressure changes
Be mindful of exterior conditions on any perimeter-based heating such as baseboards.
Good point. the process of ebulition of disolved gases draws up energy and freezes the water.
If his pump is cavitating and then compressing gases , then when you open the tap the gasses bubble up which draws up energy and cools the water perhaps
Thank God I’m a country boy ...
Easiest and quickest is just turn all your taps inside to run, not drip, might have a higher water bill next month but your water will not freeze.
Best bet - you have air trapped somewhere in the unfrozen part of your piping. This is compressed, and absent pressure from the pump tank will drive water flow from your spigots for a short time. Hot water tank is a good candidate.
You could put in a thermacube (an electric plug that only switches on when it is 35 or below, and then plug a light or small space heater in below. You can use a halogen flood light instead of the incandescent bulb if it is easier to find.
I hate the heat tape, have had it fail multiple times. Must be a quality control issue.
Nice tip on the thermocube. Freeping, like the good old days.
There is a Thermacube in there: It switches on the heated element under the water tank. I don’t put “more” on it, to extend the life of the internal switch* (and the heat tape has it’s own “thermostat”, plus, for the ~10 ft. of pipe it puts the heat right where needed.
*More pertinent, low load on the Thermacube means better reliability. The heavier the load switched, the more likely the switch (relay) will fail at the worst possible time or, at least, a bad time. (In freeze protection of pipes, failure is always at a bad time!) Of course, incandescent light bulbs switched on and off often have their own reliability issues...
In the long run I’ll probably have the Thermacube control a mercury wetted relay* that feeds both the heated element under the tank and the heat tape (as my suspicion is that the thermostat in the heat tapes is what fails, and I can bypass it.)
*I have a batch of “NOS” 5 amp mercury wetted relays from years back, but, what’d I do with those puppies??!! They are usually good for around 5 million cycles!
See other posts - possibility of dissolved gases. Under certain circumstances, it might not take much.
Certainly with the “far end” open, pressure decreases with distance along the water pipe to its exit, at restrictions. or even at sharp bends.
Ha-ha-ha-ha!!
10A too, IIRC...
Just look to your neighborhood creek for some help in answering the question. Creeks that have any water flowing will usually not freeze over until the air temperature gets down to around zero and stays there for two or three days. What that tells me is moving water resists freezing up to the point where the lack of heat in the ambient air overcomes even the motion of the water. It’s a relative equation. Water sources that are in underground pipes also bring along a steady 50-degree or so latent temperature from the soil which also helps against freezing as is true in the case of a creek where the water closest to the bottom of the creek bed will freeze last.
I sympathize with you.
I used to have my water pump and tank in a cinder block bunker and went through something similar every cold snap.
When I tore the old house down and built a new one, I made sure to put the water pump in the well and everything else contained in much warmer location.
But to be fair, it only got down to 2 degrees here.
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