Adjusting Pressure Switch (Lower) on Air Over Water Tank

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txhmownr

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I have a new 42 gallon air over water tank recently installed to replace an older galvanized one that was beginning to leak. There is no air control valve and because it is a conventional tank, no bladder or diaphragm and no valve to add air with a compressor etc. There is just an in pipe, an out pipe, and the fittings for the brass arm with the switch and air pressure gauge.

Although it is now set up for 30/50 using a control-d switch pre-set for that, I realized when disposing of the old pressure switch (which broke during removal) that it had been (for at least probably almost a decade) set at 20/40. We were never in love with that water pressure, but 30/50 is not real noticeable change.

Part of my 1 story house (and pipes) was probably built around 1992 and then greatly expanded by previous owner himself from 98 on through probably about a decade ago. I have a submersible pump (replaced 4 years ago - i think its a 3/4 or 1/2 hp, put i think 3/4 - and 10gpm) in a well probably about 100ft+ from the tank and i think i counted about 200 ft of pipe when they pulled it up to replace the pump back then.

My concern is that I have read elsewhere that increasing pressure on older pipes can cause them to leak split or break, and having had disasters of that kind in the past due to other causes, I'm not eager to experience that again. Is that really an issue in a 30 year old house?

Also, on this type of tank, to adjust the switch to lower pressure, do I need to drain it first? I have read conflicting things on this and it seems that in a bladder and pre-charged types that's normal, but on these air over water types, if I'm just lowering the pressure, can I just turn it off at the box, loosen the screw 3.5 turns. turn the power back on and open a hose spigot and watch the gauge to see if correct, close it and do that again?
 

Reach4

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I have a new 42 gallon air over water tank recently installed to replace an older galvanized one that was beginning to leak. There is no air control valve and because it is a conventional tank, no bladder or diaphragm and no valve to add air with a compressor etc. There is just an in pipe, an out pipe, and the fittings for the brass arm with the switch and air pressure gauge.

A tank with a separate in and out might be designed as a contact tank.

How will you adjust the air? Air will disappear as it gets dissolved into the water.


Also, on this type of tank, to adjust the switch to lower pressure, do I need to drain it first? I have read conflicting things on this and it seems that in a bladder and pre-charged types that's normal, but on these air over water types, if I'm just lowering the pressure, can I just turn it off at the box, loosen the screw 3.5 turns. turn the power back on and open a hose spigot and watch the gauge to see if correct, close it and do that again?
Sounds like a good plan to me. You are turning a nut on the big spring.
 

txhmownr

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A tank with a separate in and out might be designed as a contact tank.


How will you adjust the air? Air will disappear as it gets dissolved into the water.


Sounds like a good plan to me. You are turning a nut on the big spring.


what i mean by separate in and out is the pipe from the well comes in one side and the pipe to the house goes out the other

my understanding is that on these tanks air eventually dissolves into the water and so they need to be drained and recharged by simply draining and refilling the water from the system periodically and that's how it was installed as i watched (twice - i had it moved outside from closet inside the house because of water damage concerns in event of tank or pipe failure due to bad experience in past)
 

Reach4

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my understanding is that on these tanks air eventually dissolves into the water and so they need to be drained and recharged by simply draining and refilling the water from the system periodically and that's how it was installed as i watched
That is one way. However you can also leave the water in place, and add air with a compressor.

The drain method does not need a special technique to get the air right. It won't get the best run time however, because the tank will have a lot of water still when the pump turns on. That method has the advantage that there will be no blast of air if the pump does not turn on for some reason, such as the power is out.

See https://www.nationaldriller.com/art...-the-amount-of-usable-water-in-pressure-tanks
 
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txhmownr

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That is one way. However you can also leave the water in place, and add air with a compressor.

The drain method does not need a special technique to get the air right. It won't get the best run time however, because the tank will have a lot of water still when the pump turns on. That method has the advantage that there will be no blast of air if the pump does not turn on for some reason, such as the power is out.

to add air with a compressor i would need to install a schrader type valve though, wouldn't i?
 

Reach4

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to add air with a compressor i would need to install a schrader type valve though, wouldn't i?
That would be best. Making an adapter to blow air into the drain valve is probably not a good idea.
How about a photo of the stuff near the port(s) on your tank?
Does your tank have a side port or top port?
 

Boycedrilling

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Air over water tanks are SUPPOSED to have separate intake and outlet pipes.

properly set up there is a source to inject air in the intake line. It could be a snifter valve assembly or a microniser. This air infused water then enters the hydro pneumatic tank, where the air separates from the water. An air volume control (AVC) valve vents off excess air from the tank. The outlet pipe allows water with no entrained air to be used in the system.

bladder tanks are plumbed differently. This is because there is no need to capture and retain the air injected into the system. So usually the plumbing to a bladder tank is “dead ended” rather than “pass thru”.

if the hydropnuematic system has been incorrectly plumbed and there is no way to automatically add air then yes, air will have to be periodically added with an air compressor.

obviously a hydropnuematic tank system requires more maintenance. AVC’s and snifters plug or bind up. Much less ongoing maintenance with a bladder or precharged tank. So why does anybody still use a hydropnuematic tank? Cost. That’s the way my dad did it. And so on. The main reason to use one nowadays is for water treatment. There are some things that are best treated by adding air to the water to precipitate the dissolved solid or help vent a undesirable entrained gas.
 
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