Below-ground thermal/insulation question.

We are looking at repairing or replacing one of our yard hydrants this spring.  The current hydrant is frozen/non-functional and is the standard configuration below ground as show below in the photo on the left.  There are newer modifications being offered at present to the standard configuration.  One example, shown on the right, has the hydrant pipe running down to a point below the frost line inside of a PVC pipe "collar".  When assembled, there will be a continuous air column from the bottom of the PVC pipe to the top collar.....and this has me wondering:  With the way that cold air descends and warm air rises, would there not be greater risk of cold, freezing air dropping down to point where the hydrant pipe meets the water line?  In the example of the standard configuration, the hydrant pipe is surrounded on all sides by soil/fill and enjoys the benefits of that insulating effect.  Does anyone have experience with the newer hydrant-in-PVC configuration?  Any great freeze-ups that were unanticipated? One very attractive aspect of the new configs is that they allow you to pull the entire hydrant out of the PVC pipe for inspection and/or replacement without excavating the unit.  Thanks!

Interesting! I don't know the answer, but I want to know the answer :)
I put in one frost free hydrant and I'm not real thrilled with the concept. Would love better tech!

I'm interested in the answers too.  I suspect its success will depend on if you have snow cover around the hydrant.  Probably not due to trampling...  But anywhere you have snow cover, I doubt the frost gets nearly as far into the ground as the official frost depth.

Next week after our cold spell I'm going to see if the ground is frozen under our rather pitiful 6" snowpack.  

Most of the time you can pull the old style hydrant for repairs as well without digging.

The key to these are to make sure there is good drainage around the bottom of the valve body so that the water that drains out of the valve, has a place to go. I say this because inevitably someone will leave the hose in a bucket of water or stocktank, and when the valve is shut, a siphon action happens and sucks all the water out of the bucket or tank. If it is a 100 gallon stock tank, all that water has to have some place to go. Gravel, and a pipe from that gravel bed draining to daylight will work.

Another trick is to backfill around the pipe with manure. I heard sheep manure is the best, but anything with lots of hay in it, or hay itself, will help insulate the pipe.

On the onset of winter, placing some haybales around the valve body also helps to keep the hydrant flowing. All this seems silly until the hydrant no longer works and you have to haul water. Two days ago it was -5 degrees below zero and yet water flowed out of my hydrant. It was a simple, but wonderful thing to behold!

Travis Johnson wrote:Most of the time you can pull the old style hydrant for repairs as well without digging.

The key to these are to make sure there is good drainage around the bottom of the valve body so that the water that drains out of the valve, has a place to go. I say this because inevitably someone will leave the hose in a bucket of water or stocktank, and when the valve is shut, a siphon action happens and sucks all the water out of the bucket or tank. If it is a 100 gallon stock tank, all that water has to have some place to go. Gravel, and a pipe from that gravel bed draining to daylight will work.

Another trick is to backfill around the pipe with manure. I heard sheep manure is the best, but anything with lots of hay in it, or hay itself, will help insulate the pipe.....

Thanks for the interest and responses here.

Travis, when you say "pull the old-style hydrant for repairs", you are talking about just the head (spiggot), plunger rod and plunger, correct?  Because I can't see any way that one would be able to pull the entire pipe, that is attached to the water line, out of the ground.  I'm predicting that our real problem is some sort of plugging at the weep hole as we have never been able to re-adjust the plunger so that the pipe drains out. [ This all happened after a ~700 lb sow ran into the pipe and bent the pipe about 1.5 feet off-center.....I used my tractor front loader to push the pipe back straight, but even if it *looks* 'straight' how straight can it possibly be? :-(  ]   It's also possible with the heavy clay soil and high water table that the hydrant was poorly installed and did not incorporate enough rock around the drain-out area.  But the degree to which the water remains in the pipe suggests to me a plugged weep hole.....even when I pulled up the entire rod and plunger this past fall, water remained standing in the pipe.  For the record, the hydrant is positioned about 1.5 feet from the wall inside of an unheated quonset on the south side of the building.  Immediately outside the building from the quonset is a narrow strip of earth, bordered on one side by an attached greenhouse and on the other side by a concrete slab.  We did pile manure onto that strip of bare ground and it did seem to help for a while, but the temps this year are just right for producing the usual 5-6 feet of frost depth......we can thaw the water in the hydrant that stands in the top part of the pipe, but not that far under ground.

So unless I remove the greenhouse (a distinct possibility as we wish to reconstruct the greenhouse to include a pumphouse) or break up part of the concrete slab, I will have about 2 ft width of bare ground for the excavation.....just wide enough for the backhoe bucket and then digging in from there under the building to access the hydrant pipe.  [Can't dig from inside the quonset since the hydrant comes up through a concrete floor. :-/ ]  With this in mind, I'm rather keen on trying the PVC pipe collar idea as it allows one to 'adapt' the bottom of a standard hydrant to a threaded nipple that's attached to the water line.  When you want to pull up the entire hydrant, pipe and all, you unscrew the whole assembly from that nipple connection (water turned off at the source, of course) and pull the 10' hydrant out of the PVC pipe.  The additional plus that I see is that heat-trace cables could be run down the inside of the PVC pipe in the event of any needed thawing way down below.....something you can't do when the hydrant pipe itself is surrounded by soil/fill.  I've heard that you can spin off the head and pour boiling water down the pipe alongside the plunger rod on a standard configure hydrant, but with 4-5 ft of solid ice in that pipe and trying to thaw when the quonset air temp is around 0 - 10 F is not an entertaining proposition.  Just to add, because of that air temp, we don't use any hoses in the winter attached to the hydrant.....just freeze up way to fast for my wife's routine.

For those interested, one such modified collar-version of the newer hydrant installs can be found here:  http://www.seppmannenterprises.com/hydrant-assist-kit/hak/    

Based on their diagrams, it seems like it may be worth a shot (if not too expensive) although I can envision a DIY solution as well.  As many of us know well, when the hydrant freezes for good, you wish you had been more diligent with repairs and maintenance when the heat of summer was present!.....

John, two thoughts. First, the "new" hydrant in the sleeve seems similar to how city water departments have a valve in/near the street where a service joins the mains. There's a pipe for the valve key to reach down to the valve way underground, and nothing but air in there... so I wouldn't be too concerned just as long as you are below frost-line.

Second, if your standpipe was bent that much, so then was the plunger rod. Your straightening of the pipe wouldn't have straightened the rod fully, due to the "springback", so it is bent and likely jammed against the inside of the pipe making adjusting difficult.

If you could get it apart, you could maybe straighten the rod again, or replace the rod and valve parts with new and save digging it all up.

Kenneth Elwell wrote:John, two thoughts. First, the "new" hydrant in the sleeve seems similar to how city water departments have a valve in/near the street where a service joins the mains. There's a pipe for the valve key to reach down to the valve way underground, and nothing but air in there... so I wouldn't be too concerned just as long as you are below frost-line.

Second, if your standpipe was bent that much, so then was the plunger rod. Your straightening of the pipe wouldn't have straightened the rod fully, due to the "springback", so it is bent and likely jammed against the inside of the pipe making adjusting difficult.

If you could get it apart, you could maybe straighten the rod again, or replace the rod and valve parts with new and save digging it all up.

Thanks,......I'm hoping the dead-air space will help to insulate things down below if we go that route.

Interestingly, I did actually pull up the rod and old plunger this last summer as mentioned above.  I had it laying on a table as I swapped out the original plunger for an OEM replacement and decided to swap out the spiggot head at the same time.  I do not recall noticing any concerning curvature to the rod itself, but that's not to say it didn't have some and to a degree to cause the problem you mention.  On a more concerning note, I was able warm the pipe enough a few days ago to raise and lower the handle......have gotten accustomed to knowing this does NOT mean it's fixed since often I think one is just raising and lowering the ice column wrapped around the plunger rod.  What's extra concerning this time is a lack of force needed to put the handle all the way back into the 'down' (off) position....as if the plunger is not seating in it's usual place----or is no longer attached to the rod (which seems unlikely, but who knows?).  If it is no longer attached and is seated so as to block water flow, I'm not so concerned as hopefully it will keep the water from geysering once the ground thaws and the water pressure returns.  However, if the physics of the handle are what keep the plunger seated in place at the end of the rod, what would stop the water pressure in the line from blowing out the possibly unattached plunger once the thaw occurs?  Unfortunately, two hydrants are run off of that one line and we can't just shut off the main water source until spring repairs can commence or else we lose the use of the other hydrant.  But you bring up an additional good point:  Like city hydrants, some yard hydrants are starting to include parallel-running conduits down which a key can be inserted to shut the water off from the source so that the specific hydrant can be isolated from the others on a multiple-hydrant line.  Lots of things to consider if we are going to do the job right with the new install.  Thanks for the insights here!....

The way I have my water lines designed, I should be able to drain my lines in sections for the winter. Will be running them in a couple of months. I have a slope, the water main is up at the top, after that it's just clever layout and asst valves.