I just got back from a customer call, good folks to work for. And I'm stumped twice now. Short and sweet: New Woodford Y34 hydrant install, May '17, T'd into a 1" poly line passing thru to 2 horse waterers, something I've done a lot of. River run/light sand, easy digging, bucket compaction for backfilling - nothing complicated. December comes, lots of cold/snow and she freezes, but the water line passing through is fine, waterers working well, everything used daily. Owners are old ranch hands, we worked on it for a good day when it was warmer, no luck, let it ride the winter. I'm not happy - only one I've ever done that froze, my installations are solid and lines 7' deep. First end of April frost comes out, it breaks loose, dig it up and go in stages to see if I can see any problems. Test hydrant with material removed, it works fine, drains fine, drainfield and buttress for backfilling intact and doing it's job. No leaks, no seepage and a full drainout when the valve is shut. Remove, inspect, nothing out of whack. Go ahead and install new one on the chance that it might be a manufacturing defect. Take extra care with everything about the install. Wrap feed pipe with tape just for extra cold barrier. Wait for 1/2 day for pressure test, check again, and backfill. Make sure I can hear water coming up the pipe, so drain function is working. This last December rolls in, we've had a warm, open winter, moderate temps, about a foot of frost, very little snow. It freezes within a week or two of when the last one did. Same thing, waterers okay, hydrant froze so hard it cannot be disassembled. I called Woodford and asked if there was something I was overlooking (I knew there wasn't, as I've got almost 2 dozen of these in the ground and working fine, plus numerous stock waterers). We went down the list, Larry and I hadn't missed anything in trying to t-shoot. Y34 pressure limit 125psi, their lines run @ 60psi. No hoses ever hooked up in winter, so that eliminated the obvious problem. I'm puzzled big-time...know what has to be happening, but why? If anyone's got any ideas, I'm all ears. I could buy once, but not twice, within a couple weeks of each other, and on two widely different kinds of winters. If I didn't have so many around (3 on my place alone), I'd be feeling like there was something I'd missed.
Is it possible that there is some dirt, in the pipe, intermittently causing problems? We got away from any other hydrant, 'cept Baker hydrants. Every time one of the other brands goes, I install a new Baker. Big difference it that the Bakers are repairable from the top. Not that we have ever repaired a Baker... Here's a look at 'em... https://goo.gl/images/mUpGwS
I'd considered contamination of some sort, but both waterers beyond the hydrant are working fine, and they're less tolerant of debris than a hydrant. The hydrant in previous was a Simmons, and it had taken to freezing in that spot, so I went deeper with the line and bury depth, plus the other precautions. I use Woodford because they are USA made and sold by the plumbing parts outlet I get all my stuff from; they carry all the rebuild/replacement parts, too.
Did you put gravel below and around hydrant valve at bottom? I have had problems with sand....the water in sand freezes all the way to bottom unlike clay...i fixed my problem with washed rock as initial fill...i have only had that problem with sand.
I put 3/4" washed rock under around the bottom of hydrants. The clay around here has very low percolation and without the rock there is no where for the water to drain when the hydrant is shut off. Is there a chance the hydrant is not actually freezing but sand is getting into drain rendering the valve inoperable? That would explain why the water line going to the waterer never froze.
No experience with 7 foot frost lines in the South, but here're a few thoughts: 8 + feet of pipe is a bunch of water. Is the drain field really draining that amount of water multiple times ? Ask How many times a day is the water used? As in every time the hydrant is used, it drains, saturating the field. With the field saturated, it leaves water in the pipe to freeze. In the same vein, does the water table rise in the hydrant area? Again leaving water in the pipe to freeze. Or is there a leak in the line that saturates the area, but drains away when you dig up the hydrant... since you turned the water off to dig. Wrapping the stand pipe might be working against you, since you're blocking soil heat from the pipe.
Well if you had an air nozzle, you could flow the hydrant and then blow water across the hose fitting, you should hear the pitch change as the water drops into the ground. Its possible the drain valve is leaking and keeping the pit saturated.
Are they leaving something hooked up to the hydrant causing it to have a vacuum and not drain