I have two outside faucets, both frost-free hydrants (vertical pipes with actuator valve below the frost line, and check valve to drain the riser pipe when off), that have been trouble free for the 4 years we have lived here. This morning, my better half turned on the one in the barn and no water. Later in the day she tried the one that is about 75 yards farther out, on the same line as far as I know. No water. When I got home from work, I verified water working correctly in the house (we are on a well), and then went out and tried the hydrants. The one in the barn spewed some high pressure air and then water poured out as normal. The hydrant farther out worked fine too. An hour later, my spouse tried to use the barn hydrant and no water? When turned on, you can hear a little bit of air, then it is silent. There is no evidence of a pipe break underground, and no sound of water running in the house (like you would normally hear). Temperatures have been well above average (50s, 60s, 70s) during the day the last few weeks, sometimes below freezing at night. At first I thought maybe the primary feed had frozen, shutting off the two hydrants, but it has been too warm, and why did they work when I got home and then stopped working again an hour later? I am stumped. Any suggestions on how I can troubleshoot this issue? To make it even more complicated, I cannot find where the outside hydrants are tied into the house plumbing.
Thanks in advance for any help.
Additional info.
Now I am getting a water hammer or kerchunk-kerchunk-kerchunk noise at or near the system pressure tank whenever the well pump shuts off. The pressure switch operation seems normal, 30psi on, 50psi off, pressure holds at 50psi unless water is used. The kerchunk occurs right after the pump turns off, and it is not from the pump cycling (pressure switch contacts are open).