Um, We bury such pipes below the frost line here in North East Ohio.
Standard 1/4" thickness slip on, "grey", foam pipe insulation should be fin e for short periods. It also helps if you keep the water flowing should you have a real "crash" in temperatures. If your really scared, and this is ou tdoors but dry, there is always 110VAC "heat tape". You may need a kind Ya nkee or Amazon to ship you some, as I'm not so sure that sells well in Ariz ona.
Eliminate as much "exposed" pipe as possible (earth berming, etc.). Wrap the remaining (exposed) pipe in 40 mil tape (esp anything below grade). Then, a length of rubber insulation (they sell these prefabbed for different ID's -- match pipe OD). Finally, coat the exterior of the insulation with metalized tape (to protect from Sun exposure).
We moved the upstream regulator *inside* the house (garage adjoins the muni water entry) and replumbed so we only have 12" of "exposed" main (which includes the local shut-off for the house).
Beyond the entry to the house (garage), a master irrigation valve (which must be above the highest point in the irrigation system to ensure the irrig line doesn't drain *into* the muni water supply when pressure is lost/local fire fighting) feeds a separate regulator (for the irrigation system). But, there is no water in this line as the master valve is electrically "off" when not in use.
We've never had a problem -- despite being in one of the colder parts of town (26F last night).
Others wrap pipes with blankets or heat tape (and remember to turn that *on* before retiring each night).
In cold climate installations the pipe remains below the frost line and enters the house from the floor. In your case the heat tape would work fine and take very little power. Some tapes even have a built in thermostat.
I doubt it'll get below freezing under the house with only a few hours down to 15F unless there it is over-ventilated. A little insulation (as others have pointed out, this stuff is readily available) might help. If you're really paranoid, thermostatically controlled heat tape is available. It'll use no electricity until it's needed. In this case, it likely never will. ;-)
...Jim Thompson I would recommend using some heat tape. The good stuff looks kind of like
300 ohm cable. There is a semiconductor plastic between the copper leads t hat does not conduct much when above 40 degrees. At 40F it is either 3 or 6 watts per foot. Raychem used to make it, but I think they sold that line . Then cover over that with foam pipe insulation.
You can get the black foam pipe insulation in any hardware store. Even in warm climates, any decently built house will insulate the hot water pipes. Unless your Granger is totally shit, they will have the black foam pipe insulation. Insul-tube, thermacell, etc. It is used everywhere in industry.
A. Keep the water running, a trickle is all that is needed.
B. Heat Cable/Tape, Make sure you get an outdoor rated heater. Most are for crawl spaces and unheated garages. The regulator probaly will not freeze if the pipe is heated.
C. Incandesant lights can also be used in a pinch to keep pipes from freezing.
I take it you don't have a basement, our service enters 3' below the soil line. I knew some one with the same problem where the entrance was in an unheated garage. He used the light trick on cold nights, and later changed to the heat tape.
Heat tape and then wrap that with the insulation wrap. I dont have a good well house (yet) and that setup kept the well pipes protected when we had 3 days and it never got above 29F. You better get the wrap tomorrow morning before everyone is sold out.
I suspect you will have a few hours below 32F and then warm back up.
to really freeze a pipe, but if you're worried.. here's one source.. these guys can probably ship overnight to you, and a cracked tap will keep from freezing until then.
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It's been a really green (more like brown) Xmas here in the frozen north this year.. rain and substantially above freezing most of the time, at least the highs.
Best regards, Spehro Pefhany
--
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Remember the old, insulated boxes they used to make line printers quieter? Something like that.
You need to build an insulated "mast" for the vertical rise portion, like a stand for a mailbox, or the like... 1" x 4" or 1" x 6" square box around it. Insulating it from wind chill effect should be enough, but if not, you can add that heat tape they invented for trailer park 'victims'.
The horizontal part can be boxed as well, and you can make a doorway for the access to the regulator.
I second the insulated box method. You need to instrument it to be sure, but given heat from the ground on one end and the house on the other, you may not need anything more. My crawl space stays about 50F no matter what the outside temperature. The wireless remote temperature transmitters work great for monitoring that kind of stuff.
I've been experimenting in that area. I've been using a 60W incandescent light bulb in the garage for the last 40 years. Got the urge to automate it and made some discoveries.
The self regulating heat tape is made of some polymer material that degrades over time. I'd check it occasionally.
I expected a hockey-stick resistance curve like you see from some of the PTC resistors. Ain't so. Yes, the resistance goes up, but it's rather gradual. I'd post the measurements, but they've been filed somewhere just beyond the reach of my memory ;-(
This has some graphs
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I put a foot of it on a short pipe coming out of the concrete. It stabilized somewhere around 80F.
I experimented with bi-metalic electric heater thermostats. They're not designed to work down there and if you tweek them, the resetability and stability and hysteresis render them useless.
I have a battery-powered digital furnace thermostat with a latching relay. It won't go down to 30F, but you can shunt the sensor and move the setpoint up so the firmware can switch the relay in the 30F range and up.
IN the process of all this I discovered you can buy a gizmo that looks like a 3-way plug adapter that has a thermostat in it. Specs are loose, but if you can get the sensor to be the same temperature as the pipe, it might work. I bought an adjustable sensor designed to turn on a light to alert your neighbors that your furnace quit so they can call you. It's bi-metal, but designed to work down where it's needed. Initial tests in the freezer look good. Been too warm lately to test it, but should be cold enough this weekend to look at the temperature differences between the pipe and the location of the sensor.
I fully expect that I'll just use the mechanical sensor. It's likely to be good enough. The design is done on the accurate electronic system. All that's left is the boring part of packaging it. I hate boring.
Bottom line is that I've spend more $$ on gas acquiring stuff than I'll ever recoup by replacing my incandescent light. Guess that's why they call it a hobby.
Depending on where your pipe comes out, you may be better off/safer using low voltage lights, or just a resistor clamped to the pipe, for the heat source and run wire thru the wall to wherever it needs to go. Put an insulated box around the whole thing. Stick a flower pot on top to make it look like it belongs there ;-)
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