What liquid expands the most with a temperature change?

[MossRoad]

How about this $12 device plus a solar charger, battery, and 12v solenoid valve?

RioRand 12V DC Digital Cooling/Heating Thermostat Temp Control -50-110 °c Temperature Controller 10A Relay With Waterproof Sensor Probe

Robot Check

 

[MossRoad]

3/4" Brass Electric Solenoid Valve 12VDC N.C. Air Water Fuel VITON

Robot Check

 

[4570Man]

I can't obtain water from any source other than the frost free hydrant. Besides of course rain. The hydrant has to be turned off or it'll freeze. I suppose it could be insulted and heat tapped but it's still freeze in a power outage.

 

[newbury]

I can't obtain water from any source other than the frost free hydrant. Besides of course rain. The hydrant has to be turned off or it'll freeze. I suppose it could be insulted and heat tapped but it's still freeze in a power outage.

Am I the only one wondering why you have to protect a frost free hydrant from freezing?

Was it not installed correctly?

 

[4570Man]

Am I the only one wondering why you have to protect a frost free hydrant from freezing?

Was it not installed correctly?

If the hydrant is open it won't drain.

 

[davedj1]

By that point my water lines are already frozen.

Use the valve on the outside or is all this outside?

 

[Ford850]

I like MossRoad's 12v idea. I would use a battery with solar charger and rig up a 12v actuator to the handle of the hydrant. That way you still maintain the 'below frost line' drain of the hydrant when the handle is closed.

 

[Gils]

Back in college I had a teacher who had set aviation cable in his greenhouse so when it got warm it pulled on levers to open windows to vent, very simple he said. Calculate the expansion rate of expansion of the cable, put the right length of cable and it's fool proof. It is a simple setup if someone wants to calculate that.

 

[Egon]

Solar & battery with indicator light may be the simplest option.

 

[3Ts]

I probably need 10 pounds of push and 3 inches of travel. I don't think the metal could accomplish it.

Actually a small diameter of metal can push a lot more than that. The problem is the 3" of travel. However, you can use leverage to get that, you'll need coefficient of expansion and do the calculations. Put something like a scissors lift together where the cylinder moves a little and the end of the lever moves a lot.

 

[MossRoad]

I'd ditch the frost-free hydrant, bury the 12v solenoid below the frost line in an upside down 5 gallon bucket, and install an automatic drain valve like they use in a underground sprinkler system between the solenoid and the spigot. Then I'd just install a button on a post on a box with the components I listed earlier.

Or, you could install a 12v linear actuator on the handle of the hydrant. Here's one that says it has 10" of stroke and 330# of force for $10 on ebay.

Linear Heavy Duty Actuator Stroke 15N 33 Pound Max Lift DC 12V Electric Motor | eBay

 

[John_Mc]

If you do go with solar (or some other electric system), I wonder if you could use something that is spring-loaded to close, so if the power goes out, the water shuts off. (Of course, that might mean a constant electrical drain to hold it open, so maybe that's a bad idea for a solar/battery based system.)

There are mixing valves made which adjust the flow based on temperature. These take no power. I wonder what is driving the mechanical motion in those?

 

[jenkinsph]

If you do go with solar (or some other electric system), I wonder if you could use something that is spring-loaded to close, so if the power goes out, the water shuts off. (Of course, that might mean a constant electrical drain to hold it open, so maybe that's a bad idea for a solar/battery based system.)

There are mixing valves made which adjust the flow based on temperature. These take no power. I wonder what is driving the mechanical motion in those?

Tempering valves use bimetal straps and diaphragms to adjust the temperatures.