Wells, Sump Pumps and Septic Sewage Systems - Two pressure tanks but very little water

a while ago I posted about installing two pressure tanks. Well the tanks are in but it appears that I'm n better off. The 86 gallon tank only seems to hold 21 gallons and the 52 gallon tank only seems to hold 13 gallons. Does this seem right? I called the pressure tank company and the woman there said that's about all I'm going to get because the air is taking up the rest of the space. I thought that the air only took about half the space. My new pressure switch is a 40/60 and she said with that pressure that's about right. Every time I measure how much air is in the empty tank I seem to get a different reading. I know that it should be 38 lbs but the larger tank seems to have 39 although it came from the factory pre charged at 38 and I have removed air from it. Any suggestions or am I out of luck.

Water comes from the pump, not the tank(s). The pump just sees another tank as an additional load, and can even make it take longer to get the pressure up. That is about the right amount of draw down for those size tanks. Just the difference in temperature can make 3 to 5 PSI difference in the air pressure in a tank. So now that you have been replacing and adding parts at will and seem to be "no better off", maybe we should here what the problem is, so we can help figure out a solution.

You can reduce the pressure to 30/50 and that will give you a little more water volume in the tank.

Looking at page 6 the WellXtrol brochure, here:
http://www.amtrol.com/pdf/MC4380WellXtrolbrochure4_09low.pdf

You will see that a 44 gallon tank holds 13 gallons of water at 40/60 and 15 at 30/50.

You should turn off the pump, drain the tanks completely and reset them per the instructions on the first sticky.

The pressure in one should be the same in both if you have them manifolded together as per the instruction sheet.
If you lost it:
http://www.amtrol.com/pdf/9015A290revcWXT.pdf
page 14.

So now that you have been replacing and adding parts at will and seem to be "no better off", maybe we should here what the problem is, so we can help figure out a solution.

I'm betting the problem is a well production issue. So many people think adding a second pressure tank will solve the problem when in fact it can make it worse. I have tried to tell many people this in the past only to have them call me a month - and a second pressure tank - later ready to try my solutions.

I agree that you have another problem in your system that needs to be addressed, but as far as increasing the storage capacity of your tank, you can just lower the air pressure in the bladder, and leave your pressure switch alone. You can do this almost down to nothing (10-20 psi) in the bladder. This is no different than creating an artificial water logged tank...you get the benefit of having a greater storage capacity. You just have to watch the pump for the normal short cycling associated with a water logged tank, but because of your larger tanks, it should not be an issue. With minimal air in your larger tanks, you can still probably achieve the pump draawdown cycle similar to a normal system with one small tank properly charged.
We do this often when a customer has a low yielding well. We install a flow restrictor on the well pump, to match actual well yield, and several large pressure tanks. We then use a high quality pressure switch which can be set with a small differential...to make the pump come on as soon as possible....usually like a on/off around 63/65 psi. I use this on wells in the 1-4 gpm range with great success.

Thanks for all the advice, what I had meant by being no better off was that I thought I would have enough water in reserve to keep me for a few days if the power went down and also for keeping the pump from going on and off there by saving electricity and the pump. Now I realize that even before I started my quest my 52 gallon tank only had about 8 or 9 gallon in it. So I guess I am better off since I have an additional 21 gallons which I didn't before. The larger tank only cost me $60 dollars at Lowe's, it seems as though no one was buying the larger tanks so they just wanted to get rid of them.

We do this often when a customer has a low yielding well. We install a flow restrictor on the well pump, to match actual well yield, and several large pressure tanks. We then use a high quality pressure switch which can be set with a small differential...to make the pump come on as soon as possible....usually like a on/off around 63/65 psi. I use this on wells in the 1-4 gpm range with great success.

The way VAWG describes above is the only way to get any storage from a pressure tank. However, with a higher producing well and pump, say 10 or 20 GPM, the 63/65 pressure switch setting will cause the pump to cycle on and off rapidly. A 1 to 4 GPM well or pump will not cycle nearly as fast.

With a regular 30/50 or 40/60 pressure switch and high producing well and pump, you cannot get any stored water from a pressure tank. This is because you have no way of knowing if the pressure is at 60 and the tank is full, or if the pressure is at 41 and the tank is empty, when the power goes off. Murphys law says the pressure will always be at 41 when the power goes off, and you only have a quart of water in the tank. You can lower the air pressure in the tank from 38 to 10, then you would have a little water stored in the tank(s) when the power is off and the pressure drops below 40. However, this will also cause your pump to cycle on and off rapidly during normal use.

The best way to have water when the power is off, is to have a generator handy.

Hey VAWG, that is a good trick for a low producer. What kind of pressure switch are you using?

I do agree that it would give you more storage but the water you get will be at such low pressure is it really worth it? Plus a well will generally have some kind of iron content and when you use the method VAWG described, the water you get from the tank toward the end of the capacity will be discolored and have substantially more sediment.

I guess the real question is does it solve your problem. If it does and you're happy with the results then that's all that matters.

Allen Bradley...they only come with one pole, and so you need to use a contactor and just run the coil through the switch. They aren't cheap though, around $150 wholesale...but you can dial them in really well.

Yeah I use a lot of those AB836C7 switches myself. They do work good but, I thougt you may have found a different switch that would let you narrow the bandwidth. Thanks though.