Freeze-Proof Hydrant Whistling

[Rusty]

This is a new one for me. I have a freeze-proof hydrant in the barn. Its been in operation since 1994, and except for one freeze-up when I forgot to unhook a hose, it has worked without any problems. Two nights ago, I noticed that it was whistling while shut off. It was faint, steady and sounded similar to a teapot, but a little lower pitched. The next morning, it was still whistling and was much louder. The whistling would stop whenever the hydrant was actually opened to draw water, and resume as soon as the hydrant was closed. It was still whistling last night. Today, its quiet, except for 3 short chirps immediately after it is closed. We have been between 15F and -5F during this period, with today actually being the coldest. Any ideas?

 

[midlf]

my guess, and it's just a guess, the whistling was a bit of water flow, not enough to come up the pipe but enough to make a valve whistle.

 

[gordon21]

Whisting is moving air making noise. If the valve at the bottom were leaking, the pipe will fill up and freeze. Cover the end of the faucet with duct tape to see if that stops it. It's just a hunch, but the wind might be blowing across it at some weird angle and the pipe is your whistle. You can make a piece of 2x2 lumber whistle like a train if air crosses it at the right angle fast enough with the right shape hole at the end. The temperature might affect the sound. Has it been windy and very low barometric pressure? Sound travels better in lower pressures so you may be hearing it better.

 

[Rusty]

midlf-Thanks, I suspect air movement, also, but haven't come up with a way that would happen. I would think that a small water leak would drain into the ground until it filled the available volume (if it ever did), and would then fill the pipe, and eventually begin to drip from the spout.

Has it been windy and very low barometric pressure? Sound travels better in lower pressures so you may be hearing it better.

gordon21-I just got in from the barn. The hydrant is quiet, except for 2-3 short chirps after it is closed. It has been very windy, however, the barn doors are closed and the hydrant is in the barn, sheltered against a wall. Barometric pressure is currently at 30.00 in. Hg. It has risen in the last 6 hours, but I don't know how low it had been. If the whistle returns, I will try the duct tape.

 

[SPIKER]

the whistling is water leaving the frost proof fixture, don't tape it off it will act like the hose did and not let it drain back it is water running out of there which keeps it form freezing.

markM

 

[Rusty]

More of the story - This story is not over yet, but I found two problems that were probably contributing to the whistling hydrant.

First, there is a slight leak of water out of the packing nut when the hydrant is open. I believe this water freezes when the hydrant is closed, causing the mechanism freeze-up (hydrant was frozen on five consecutive mornings). It also appears to be where trapped air escapes under pressure producing the whistle.

Second, the valve plunger is leaking below the freeze line when closed. Leaking water fills the drain volume and then pressurizes the hydrant. The leak became apparant when the barn (earthen) floor around the hydrant became saturated. Pressure in the pipe forces the air that is in the hydrant pipe past the packing nut producing the whistle.

TSC carries a hydrant repair kit $22, but I'm going to wait for warmer weather. My work-around is to turn off the water to the barn, except when I go out to fill buckets. So far (4 nights), this fix has eliminated freezing of the hydrant mechanism, saturation of the floor and the whistle, except for 2-3 short chirps when the hydrant is closed.