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.