Does a well need a vent on the cap?

Does a water well need a vent on the cap?
My wall has a weird cap because it once had as an old fashioned windmill setup. There is just one small hole, and the wires come out of there. It does allow venting around the wires, even if that is a small amount. The problem is that rain water can enter from that hole. I've always kept an upside down pail on it to prevent water and bugs from entering. We're doing some work to this well and a guy told me to just out silicone around the wires. I know that will seal the hole, but dont the well need some venting to allow air to displace the water that is pumped out? It would seem to me that not having a vent would make the pump work extra hard, and create a vacuum in the well, which might cause other problems.
Or, does the water entering the well make up for the water removed?
Anyone know?
Thanks
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On Nov 23, 4:00 am, snipped-for-privacy@home.com wrote:

add height to the well top, so water cant enter. surface water in a well is a bad idea
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wrote:

The well is plenty high. About 2 feet exposed casing and on a mound. It's just rain water that can get in. The rain water in itself is probably not bad, it's the dust and dirt the is on the cap, and water dripping off trees and such, that goes in with it that is the problem. Not to mention bugs.
As to another reply, the well is 300ft. deep, the pump is at about 280 to 285 ft. down.
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On 11/23/2011 1:00 AM, snipped-for-privacy@home.com wrote:

All wells need an air vent. Not because of water, but because of air pressure changes. Your air pressure is always changing. Check your daily weather report and notice the change in barometric pressure.
Your well is probably not very deep. My well is drilled to 650 ft. The water is down perhaps 500-550 feet. that is a lot of air space. The well cap allows air in and out of the well. Many times you can hear it whistling. Sealing the well would eventually create a vacuum and make the pump work much harder to get the water up and out of the well.
My well has a small, well insulated building over the well. It is well insulated because it needs an electric heater to keep the outgoing water line from freezing.
Here is what happens when the winter air here gets to -15. That occurs usually when a high pressure system passes over Central Oregon. The high pressure forces the -15 degree air through the vent in the well where the air expands, cooling the already frigid air to way below -15 degrees. This cold air causes the water in the pipe at the well top to freeze solid.
When the water in the pressure tank goes down, the pressure switch tells the pump to pump. It pumps against the frozen water in the line, but no water gets to the pressure tank. So the pump just runs and runs and the house still has no water. Eventually the pump burns out and you are screwed.
This happened to the previous owner. So he kept an electric heater in the well house. I do the same. One winter, I set the heater control too low and it never turned on. When the house water stopped one really cold day, I knew exactly what was wrong. I turned off the pump and turned up the heater control and then tried the pump about once an hour. Finally the warmed air in the pump house going down the well vent hole thawed the frozen pipe and all was working again. Whew!!!!
When your well had a windmill, and if it ran in the winter, a frozen pipe would either break the pump or force water back past the leather packing in the pump. Either is not good. I suspect the windmill was not used in the cold of the winter.
Paul
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I agree. That air is barely moving and going through a pipe intended to support free flow, not create a pressure differential like an orifice in an HVAC coil. Any change in temp is going to be very small. I can see the pipe freezing near the top of the well head just from the cold -15 air though, without additional cooling.
I think the main issue today with having a well vent is to eliminate any negative pressure in the well. If you have negative pressure, it would make any small leaks worse that could possibly result in ground water getting in around a seal, etc. How much of an issue it really is, who knows.
The OP could check with his local code office or try googling for his state info which might be online.
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Yes, wells do need a vent. The vent should not allow surface water to enter the well. The quote below is from:
http://www.idph.state.il.us/envhealth/factsheets/drilledwlsFS.htm
An approved well cap or seal shall be installed at the top of the well casing to prevent any contamination from entering the well at the surface. A well vent is required. The well vent pipe shall be at least ½ inch in diameter, 8 inches above the finished grade, and be turned down, with the opening screened with a minimum 24-mesh durable screen to prevent entry of insects. Only approved well casing material meeting the requirements of the IWWCC may be utilized. To prevent contamination, the annular space between the drill hole and the well casing shall be grouted below the pitless adapter or unit in accordance with the IWWCC.
Dave M.
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