Hydro-pneumatic water tank


Old 07-04-01, 08:07 AM
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We have an older home that has a hydro-pnematic water tank. What is the correct procedure for setting it up? The pressure gauge drops quickly when a faucet is opened or the washing machine fills up for example and as a result the well pump is constantly switching on and off trying to keep the pressure up. According to the pressure gauge the high pressure is arround 60lbs and the low pressure is around 35lbs. Any ideas?
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Old 07-04-01, 12:13 PM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
Posts: 10,952

The pressure in an air-bladder tank should be two psi below the cut-on pressure (usually 18 for 20-40, and 28 for 30-50).
You can check the tank bladder pressure with a tire pressure gauge at the air valve near the top of the tank. If it is too high, bleed it off. If it is too low, air it up with a bicycle pump or portable air tank or compressor.
Most residential water pumps are set 20 psi apart for on-off, i.e. 20-40 or 30-50.
You can adjust the on-off with the pressure switch. If it has two spring-loaded nuts, the larger is the cut-on, and the smaller is for the cut-off. If it has just one, it will be factory pre-set 20 psi apart.
If you're uncomfortable working around exposed hot electrical wiring while the pressure switch cover is removed to access the adjusting nuts, unplug or turn off the breaker to the pump.
You turn the nut(s) down to increase pressure, and up to decrease pressure.
If you have a standard 1/2-hp or 3/4-hp residential pump, it probably should be set no higher than 30-50. I think that your pressure settings are too high, which is causing your pump to cycle too much.
I would back off on the pressure settings, and see if that doesn't help.
Good Luck!

Old 07-05-01, 07:18 AM
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Thanks for the suggestions "Oldguy" lowering the water pressure sounds like a good idea. I do have another question. There does not appear to be a pressure valve at the top of the tank only at the water input point at the bottom of the tank where the waterpipe comes from the well. Is it possible that the tank does not have a bladder? After all it does look extremely old! If so, do you have any suggestions on how to set it up? Once again thanks for the input.
Old 07-05-01, 07:45 AM
Join Date: Dec 1999
Location: Northeastern NC On The Albemarle Sound
Posts: 10,952

It may have its air valve near the bottom, or no air valve at all. Depends upon the type. Whatever kind of bladder tank that it is, if the bladder goes, it would need to be replaced in any case.
It is probably o.k., if it is an air bladder type.
Is the tank painted or galvanized? If it is galvanized, it will have an air volume control on it (looks like a little flying saucer with a plastic tube coming out of it).
Just adjust the pressure switch to see if that doesn't solve the problem.
Good Luck!

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