I'm one year into a new house we bought that was built in 1971. Water is served from a well that I don't have a lot of specific info on. In 2010, there was a 1/2 HP Goulds submersible pump installed set at 300' using 1" poly. I spoke to the installer and the only extra detail they could give me was that when they shocked the well and flushed it all day, they didn't come close to running out of water. When someone is taking a shower and nothing else, the pump kicks in at what looks like 30 PSI and runs for 45sec to hit 60 PSI. During a typical shower the pump kicks in 2-3 times.

Inside the house I have a harvard mark 10 tank that is as tall as I am ~70", and the pump installer tells me it is an 80 gallon galvanized tank, likely installed in 1971. It is in need of replacement soon. I'm told I can replace the current tank with a 20-30 gallon amtrol tank which would suitably replace the current tank. The house is a 3 bed 2 bath with two adults and a child right now. If things work out, we will hopefully have a second child in the coming years. I have plans to remodel the master bath, and the wife has mentioned the possibility of adding a few shower heads in the new bathroom. Here are my questions:

1) Using the methods for estimating demand, it seems like my current demand would be about 9-10 GPM. Should we go with an extra shower head that load could move up to somewhere around 12-15 GPM. With my current pump, can I meet that demand moving to a 20-30 gallon Amtrol?

2) Based on my current demand, can a CSV work for me with the recommended 4.4 Gal tank? It seems like the CSV system is limited by the output of the pump in the well, or alternatively would require a larger than 4.4 gallon tank?

 

Have you been officially welcomed

I look at the charts for pressure tank replacement and then upsize. I would rather have the pump run a little longer than more often.

As far as going with the CSV (cycle stop valve) I don't know much them it or how it's sized.

I'm a large expansion tank person.

 

Welcome to the forum.
From what I know (Been working with my well/filter system for a year now), a slightly smaller (then your current) blader tank would make a world of difference. The thing to remember, at full pressure, a blader tank is only half water (give or take).
As with PJMax, I'm a big (size) tank guy as well. Our tank is actually a bit too small for our up and coming demands. We have 3 small children, so current demand isn't bad yet.

I've read about those CSV's but am not excited to jump on that waggon. It sounds like a good idea, but I'm all about long term proven tech (and keeping it simple).

 

I am on a well and technically have an over sized pressure tank. I have never had a need for a cycle stop valve so to me it seems like unneeded expense and complexity.

 

20-30 is way too small. That's less than 10-15 gallons of water where you have 30-40 gallons of water in the tank now. I guess it's because of sticker shock that people are constantly under-sizing their tank.

When someone is taking a shower and nothing else, the pump kicks in at what looks like 30 PSI and runs for 45sec to hit 60 PSI. During a typical shower the pump kicks in 2-3 times.


That's great. It means your pump and well is in good shape. It's keeping up with demand and more. Lots of people would be envious.

Amtrol/well-x-trol has a website and a sizing chart. From it and guesstimating, a 44 gallon tank or bigger would be what you need. I am guessing 15gpm pump output.

http://www.amtrol.com/media/document...sizingCard.pdf

If someone else wants to guess what your pump puts out and read the chart, I'm not proud.

 

I looked in a little more detail and found that the pump is rated at 5GPM. The model is Goulds pump 5gs05.

Thanks for the input

 

Just so you know, when you take a shower, if your pump kicked on for 45 seconds and it pumps 5 GPM, you are only getting 3.75 Gallons plus what the shower puts out in 45 seconds. So maybe 5 gallons total. Just because you have an 80 gallon tank, it does not mean that you get 80 gallons of water before your pump refills it. As was already mentioned, the most you will ever get is 1/2 of what the tank size is.

My point is, a 20 to 30 gallon tank will probably give you 10 to 15 gallons or 2 to 3 times what your current tank is doing for you right now. So if it fits right then go for it. As a rule of thumb, always get as big of pressure tank as your space will accommodate. This will ensure that your pump cycles on less often. Also, since your 80 gallon tank is currently only giving you 5 gallons of water, I would pretty much say it is toast. Just an educated guess.

 

A galvanized tank generally does not have a bladder, so it's all water most of the times.

 

"A galvanized tank generally does not have a bladder, so it's all water most of the times."

I thought it was half-and-half, too. Or three quarters water. Something like that. I've seen one with a glass on the side and it wasn't all water, but it's been a long time.

 

I'm confident the tank is on it's last legs...
for those interested, this is what I'm dealing with:


Pump control box:


Pressure switch:

 

I don't know very much about galvanized tanks, but I do know that the pressure comes from the air in the tank, not the water. If it was completely full of water you would have no pressure. That is why the maximum drawdown of water, between pump cycles can only be 1/2 the volume of the tank. The way the physics works is that the more air volume the more drawdown and the more water volume the more drawdown. Since the air volume and the water volume must both be in the same tank, the maximum amount of both volumes can only be 1/2 of the volume of the tank. If you take anything away from the air volume or water volume, you will get less drawdown. That's how it works.

That being said, if there is no bladder in the galvanized tank, then the pressure he is getting is coming from the air that is trapped inside the tank when the water initially filled it. Unfortuneately if that air is not separated from the water with a diaphram, then overtime that air will dissolve into the water, reducing his air volume and consequently reducing his drawdown water volume. He will need to completely empty the tank and refill it on a regular basis to re-establish his maximum drawdown.

If it was me. I would get a pressure tank with a bladder and get rid of that relic. I would bet a 20 gallon tank with a bladder, set up properly, would give him as much water as the 80 gallon one he has would. That being said, bigger is better, when it comes to pressure tanks even when they have bladders.

 

That's an excellent description

At my old shop..... the air in the old galvanized tank would only last for a couple of months or so. I installed a schrader valve on the tank and would occasionally put in a small charge of air.

 

Yes, manually adding more air after the water gets in the tank would work as well and help a lot.

I should also add, that although 1/2 the volume of the tank is the maximum one will get for drawdown, almost no one ever gets that much. There are other things that make a difference, like where the cut in and cut out pressures on the pump are set and changing air and water temperature, etc. I usually tell people that if you are getting 1/3 of your tank's size in drawdown, you are doing pretty good.

So in reality, a 30 gallon tank will only put out around 10, maybe 12 gallons of water, on a good day.

 

I don't see any rust on that tank. That's what makes galvanized tanks go bad -- rust through that starts on the outside. Just because it's old doesn't mean it is bad. Those old tanks lasted a lot longer than the newer ones, especially when kept inside.

So why does it need replacing? Resetting a tank is no big deal. My mother learned how to do it.

 

PJMax,
If you had reset the tank properly, instead of just adding air, it would have needed a lot less attention. I'm trying to remember, but 9 months between resets is about right, I think.

 

I agree that there is probably nothing wrong with his tank. It is just that without a bladder, I find it a real pain having to reset it regularly. I find it is usually a little more frequently then every 9 months, but that might be the time where the drawdown falls to a cup of water or so and the pump cycles on and off constantly when water is used. I usually address it long before that.

The other problem is that you cannot pre-charge a tank, that does not have a bladder with pressurized air at the 3 psi below the cut-in pressure. His pre-charge is 0 psi. What that means is that even when he re-sets the tank it probably has about 55 gallons of water in it when the pressure reaches his cut-in value (30psi). This means that the tank will always have 55 gallons of water in it when the pump goes to refill it again. After the 55 gallons the tank will be at about the 65 gallons full when it reaches his cut-out value (60psi). So his 80 gallon tank will provide a maximum drawdown of 10 gallons of water when optimized with a re-set. And that drawdown will reduce overtime as that air dissolves into his water.

Now the optimum way to re-set a non-bladder tank, if it has a schrader valve like PJ's did, is to empty the tank. Now turn on the pump and let it fill with water until the pressure just starts to build (maybe 5 psi). Now turn off the pump. In this case, there should be about 10 gallons of water in it at the 5 psi point. Now add compressed air to the Schrader valve until it reads 30psi. Now turn the pump back on and let it fill. With this method the cut-out pressure should see the tank with about 38 gallons of water in it. So his drawdown will go from 38 gallons to about 10 gallons and therefore he will get about 28 gallons of water between pump cycles. Of course it will decrease over time again, as that air dissolves into the water.

I would just install a new tank with a bladder and leave the physics to someone that cares. lol.

 

Uh, uh. Not that hard.
Try it this way next time.

Instructions to pressurize a Galvanized steel pressure tank:

1. Turn the power OFF to the well pump.
2. Open the drain at the bottom of the tank until the pressure on the gauge is down to 0-psi...
3. Take the gauge out (that breaks the vacuum on the tank)...
4. Empty all water from the tank....
5. Apply thread sealant to the threads on the gauge, then replace it.
6. Close the faucet...
7. Turn the power back on...
This will start to refill the tank with some water, but will properly give the tank the air charge/cushion needed for proper operation.

Read more: http://www.doityourself.com/forum/we...#ixzz2Qw6cbYYd

This should get you very close. The trick is to break the vacuum and get ALL the water out. If you don't do that, it's no wonder you are doing all this crazy stuff.

My mother used to take the valve out of the schraeder valve to break the seal.