I suspected that might be the issue, but I didn't want to mess anything up by opening and closing valves (we are first time homeowners, so I am used to calling the super for this sort of thing!). The pipe from the outdoor spigot looks like it runs back to the boiler area so I'm sure it's connected to the rest of the system. Here are some photos of the valves by the meter (the yellow one seems to be in the off position, maybe that's the problem?):

The yellow handle is on,red handle is off. That boiler drain attached to the frostproof facuet make's me suspect a larger problem might be lurking. Listen for water escaping inside wall after you get faucet working.

Klem, I had no idea what a boiler drain valve was so I just googled and now I see that the faucet is really just the two beige knobs, and the reddish knob is a boiler drain valve. Why on earth would that be attached to an outdoor faucet? Can (or should) I remove it? The former owner was an architect and employed a lot of "creative" workarounds on various projects in the house, so I have a feeling this might be one of them.

The previous owner probably added the second valve because the frost-proof valve leaked due to a worn washer.

I agree the second valve was likely added instead of simply changing washer in frost proof. That is easily reversible but possibility that frost proof froze and burst inside wall as result of second faucet is what must be checked before calling job complete.

Okay, I think I understand! However, I still don't know how to get the water flowing to that faucet. There are three valves near the water meter - the yellow one (which I now understand is in the on position), the red one (in the off position) and a white one that I can't read because it is between the pipe and the wall, but I assume it's in the on position since it is parallel with the pipe:

Should I try turning the red one to the on position and see if that gets the outdoor spigot working? I am a big wuss when it comes to fiddling with this stuff - years of apartment living will do that to you!

Welcome to home ownership.

The type of valve you have with the lever is called a ball valve (inside there is a ball). When the lever is in line with the pipe, it is on. When it's perpendicular to the pipe it is off.

Trace the pipe back from the outside faucet until you see a valve that is off. So far, the only one that we've seen in the off position is the orange handled valve 4th photo (with measuring cup).

Close the hose bib outside and then open the closed valve a little. You should hear water fill up the line and then stop. Then go outside and open the hose bib and see if you have water.

If this is the correct valve, open it all the way and put a tag on it so you can find it again.
You will want to repair the hose bib outside and remove that second shut-off before next winter. Outside faucets need to be able to drain so they don't freeze and that extra shut-off can prevent that. Also, in the winter you want to remove any hoses that are connected - also so this can drain properly.

BTW: The yellow handled valve below the meter looks like the main shutoff. Tag it so that you know where it is if you should need to shut the water off to the house in a hurry at some point in the future.

Thank you Jake! Do you mean the only valve in the off position is the red handled valve, though? The white one is parallel to the pipe to which it is actually attached, although that pipe makes a 90 degree turn right next to the valve.

I tried to trace the pipe back to the source but I lost track of it under a drywalled section of the basement ceiling. If there are no crazy turns under the drywall, then I think I know where it comes out, but this is an old house so I never take any straight lines for granted! Regardless, there is only one valve in the off position so we'll test it using your instructions for closing off the hose bib outside, etc.

Yes, sorry, I edited my response seconds after I posted it.

Are you sure that is a boiler drain valve connected to the cold line, because I can't really tell. My boiler has a drain valve, but also has a water supply line connected to the cold tap so that it can automatically refill the boiler if the water is low. If the cold water line runs to a boiler fill shut-off valve, there should also be an autofill device for the boiler. It will probably also have a fast-fill lever that allows you to fill the boiler more quickly by cycling the lever.

If you need to repair the freeze-proof hose bib you may have to look around a little to find exactly the right washers or other parts. I bought the 1/4 turn version from HD about 3 years ago and they had all kinds of them in stock, for all different depths of wall. I went to buy a 2nd one about 6 months ago and in most lengths all they had was the gate-valve style.

Bruce

Bruce, I'm not sure what you mean - are you referring to the boiler drain valve connected to the outdoor spigot, or what looks like another one (red knob) indoors near the water meter (in the photo that also features my curious helper cat)? If you're referring to the indoor one, I have no idea if that is actually a boiler drain valve nor why it's there. I'm not at home at the moment, but when I get back this evening I will try to take a shot that shows how all three of the valves are attached to the pipes leading to the meter - hopefully that will make it easier to understand how the system fits together.

I think there was some confusion: To clarify, the reference to a "Boiler Drain" was the second shutoff on the hose bib shown in the first photo. In this conversation the function has nothing to do with a boiler - it's just that someone used a boiler drain valve after the hose bib... probably because the hose bib leaked.

The only time boiler drain has been mentioned was in reference to that attached to frost proof faucet outlet. The poor man is having enough difficulty without conjured up and off the wall statements.

Well, I just discovered another valve much closer to the outdoor spigot - it was hiding behind some boxes we had stacked nearly to the ceiling! Might be too dark to see in this photo but there's a valve in the off position on the pipe just above the lower corner of that box, about 3 feet from the outdoor spigot. I'll check it using Jake's instructions tomorrow morning but I'm sure that's the valve.

However, looking at the other valves by the meter, I'm confused about the system in general. Here are photos of the whole thing:

It looks as though we might have (or might have had at one time) two places where water comes in from outside. The yellow valve looks like it controls the older-looking pipe close to the floor, whereas the red and white valves (they are on the same line, I think) control the newer-looking copper pipes at shoulder level. Both eventually lead to the water meter. Is there some reason why the newer looking one should be turned off?

I think your new found valve is probably the one you want.

Looking at your other piping I'm having a hard time figuring out what was done.
I think there are a couple of possibilities:

1.) They installed a new remote sensing water meter and left the old one in place. It does look like the water service line was switched out at some point also. This looks like the most likely situation.

2. They have two meters - one goes for just the outside water so you don't get charged for sewer for the water used for irrigation.

Success! I turned on the newly found valve today and lo and behold, water! I listened for leaks and didn't hear anything, so I think we're okay there. The outdoor faucet is definitely a mess though. Most of the water comes shooting out of the tan knob at the top - can that be fixed by replacing the washer?

I'm still mystified by the two inlets near the meter, but I'll start a separate thread for that. Thanks everyone for your help!

The tan knob at the top looks like the vacuum break. Here's what I would do at this point... I'd turn the water off at that shutoff, and then replace the entire assembly (frost proof sillcock). You can get the whole thing for $30 at big box hardware.

Note that if you go this direction you need to unscrew the sillcock from the copper pipe while holding the copper pipe from turning (so two wrenches).

Frost proof sillcocks come in various lengths - match what you have. Also match the end that connects to the plumbing (is probably 1/2" male threaded).

While you are there at the hardware store you will need a small roll of teflon tape to wrap on the pipe threads before you assemble again to prevent leaks.

You will also need a can of "Great Stuff" or similar foam. With the new sillcock connected and properly in place, foam the opening around the sillcock from the inside so it's sealed up and keeps out air, bugs and critters. You don't want foam outside, so the new sillcock should be positioned tight against the house. If foam does get outside, don't mess with it until it's dry... then cut it / clean it up.

Thank you so much for the detailed instructions! This will be this weekend's project.

My first thought when I saw this was replace the entire sillcock if your able to. Depends if they used a threaded connection or if it is soldered inside the house. Threaded is a simple fix, soldered not as easy.

With that second valve they threw on there it stops water from correctly draining out of the faucet so it doesnt freeze and cause damage.

So on the new sillcock, just make sure it is sloped down a little so water runs out when you shut it off.

I would be very interested what that Y shaped fitting is under that the
second meter. If it directs water from one side and up to the meter and
back down and out the other side then that would make more sense.

Edit: Greg figured out what the Y fitting is in the other thread.