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Everyone seems to suggest using those styrofoam faucet covers to help prevent the pipes associated with the fixture from freezing.

Foam Faucet Cover

They're cheap so I have them anyway (plus I'm not in a hard freeze area), but I'm skeptical about how much protection those things provide.

I'm wondering if anyone has some actual numbers?

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I imagine it depends mostly (entirely?) on how cold it gets and for how long. – DA01 Jan 21 '14 at 19:29
@DA01: I guess I was looking for something along the lines of how much heat (in degrees?) differential these things might keep inside them. I'm guessing that they're probably only effective somewhere where the temperature might dip below freezing at night, but then rises above freezing during the day. However, none of the articles that advises using these things seems to say anything like that. I was just looking for data that's more concrete than, "hey, it's Winter and you should put these on your faucets". – Michael Burr Jan 21 '14 at 20:08
I think that's the best way to think of them...shields against temporary temperature dips below freezing. Useful in perhaps coastal PNW. Likely useless in Northern MN. – DA01 Jan 21 '14 at 20:13

I live in Canada and there are only two ways to stop your spigot from freezing in the winter. The first is to have a cut off inside your house, lower then the spigot and it has to have a relief valve on the exterior side to drain the water away from the wall. The other way is a frost spigot that extends about 20" into the warm zone on the inside of the wall. This actually has the shut-off all the way into the house. These have to be installed with a slope towards the faucet end so when you close it the water drains out the spigot.

Those are the only two ways to truly and confidently stop your hose spigots from freezing.

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I know this to be true. I have had many neighbors in MA rely on these, only to have them fail. I have a shutoff and drain mine from the inside of the house. However, $3 is pretty cheap as far as placebos go if it makes your feel better. – BrownRedHawk Mar 2 '15 at 18:25

This seems a bit gimmicky to me. Insulation is not 100% effective, so if no heat is added to the system the inside temperature will eventually be equal to the outside temperature. This might work for an overnight frost, but I wouldn't rely on it for an entire winter (especially a cold northern one).

If you live in a climate where temperatures rarely dip below freezing, this might be worth it. If you live in the frozen north, you might use this to keep your giblets warm while you snowblow, but that's about it.

If you're really worried about the faucet freezing.

  • Turn the water supplying the faucet off (hopefully there's a shutoff that controls only this faucet in a heated portion of the home. If not, you could install one).
  • Open the faucet, and leave it open until the cold weather has passed.
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+1 The heat added is the warmth of the material inside the faucet and the pipes themselves. If copper, the inside warm pipe should heat the pipe extending outside and the insulation should hold it in. Also the inside water in the line is above freezing. All said, I agree you shouldn't depend on it. – bib Jan 21 '14 at 15:37

They help. Last frozen spigot issue I dealt with was with a "frost-poof sillcock" (the long faucet that has the valve on the inside) and it probably would not have frozen if it had one of these on it.

frost-poof sillcock

Those are supposed to work on the principle that the valve and water are on the inside of the building, but in very cold weather the exterior part still gets cold, and the exterior cold conducting in along the metal pipe exceeded the interior heat conducting out, so the pipe attached to it (on the inside, beyond the valve) froze anyway.

One of these covers significantly reduces the rate at which the outside part conducts cold, so it can tip the balance. If you prefer, it reduces the rate of heat loss from the outside faucet, retaining more of the heat conducted from inside along the pipe (same thing, said differently.) Heat comes from the inside of the building being heated in winter.

I fixed that one by the traditional method from before "frost-proof sillcocks" (perhaps better referred to as "frost-resistant") of putting a valve with drain further back along the plumbing. Both methods require someone to remember to do something with the faucets before winter, which can be a problem.

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pedantic nit pick: cold can't conduct in--though heat can be lost outward via conduction :) – DA01 Jan 21 '14 at 20:52
And it was precisely for pedants that I included: If you prefer, it reduces the rate of heat loss from the outside faucet, retaining more of the heat conducted from inside along the pipe – Ecnerwal Jan 21 '14 at 21:04

The one time I had a problem with frozen pipes, it occurred inside the wall itself, approx 2 feet above the faucet. In this case, insulating the faucet would have been of no help whatsoever. I resolved the problem by:

  1. Adding additional insulation inside the wall, between the pipe and the outside.
  2. More importantly, before the first freeze of the season, I turn off that faucet's water at the source, then open the faucet and let all the water drain out.

Since those two steps, I've had no further problems with pipes freezing.

I live in Northern VA, so this info may not be applicable to places with more extreme winters. Hope this helps anyway, though.

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Check out "frost-free hose bib" for a hardware device that implements this good procedure. Basically an elongated tap with the handle and spout on the outside, and the washer/seat mechanism a foot or so away on the inside... – DJohnM Jan 21 '14 at 18:32

I have a faucet inside the garage that is frozen. It's a standard spigot and I can't get to the pipe that feeds it so I can't install a shut off or replace with a freeze proof spigot. My plan it to use one of these covers along with a 7 watt night light inside. I may put a tin can inside as well. Maybe this idea will help someone else.

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I was going to try an do an experiment sometime over this winter with a couple EL-USB-1 temperature loggers - one outside and one inside the foam, but it never really got cold enough here (thanks, Global Warming) and my friend with he second temperature logger has moved on to another job. So my experiment may have to wait until next winter :( – Michael Burr Mar 2 '15 at 18:22
Please report back once you have results. Thanks! – Niall C. Mar 3 '15 at 4:31

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