Help with Pressure Tank on irrigation well

[Carbidetooth]

I need to replace leaking old style pressure tank(s) and hoping for some guidance on sizing. Space for tank(s) is restricted in height.

Situation:
Former domestic well now used for irrigation only. Pressure tanks under house were hooked up conventionally, feed into both tanks, output on backside of left tank. Original output now abandoned, household water is now on city supply fed from opposite end of house.

I imagine pump originally was a jet pump, later changed to ¾ HP submersible which is about all I know about it other than the pressure switch is set on at 40 lbs., off at 60 lbs. I’m assuming that when switch was made to city water the well was dedicated to irrigation.

Judging from what I can see, (no water output from tanks) the well-to-tank-line was teed with one leg of tee going to irrigation backflow preventer and other leg going to tanks. That seems unconventional, but I imagine it works in the same way as if the water input and output were at the tanks.

Anyway, all that said, I need to get system back up and running with a tank that doesn’t leak so here are my questions.

1. Do I need to do a similar twin tank setup because of height restriction (36”-38”)?

2. What size tank would be appropriate? For comparison that’s a 40 gal water heater next to pressure tanks, so I’m guessing the pressure tanks at 35-40 gallons.

3. Can I lay an upright tank on its side? That would allow more capacity in a single tank.

Any and all advice appreciated.
Thanks, Peter

 

[Reach4]

This would seem to be an ideal use for a Cycle Stop Valve. You will irrigate for long periods as opposed to flushing a toilet 15 times per day. You can then get by with a fairly small diaphragm pressure tank, so you will save a lot of space and maintenance vs the old galvanized tanks you have now.

 

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[Carbidetooth]

This would seem to be an ideal use for a Cycle Stop Valve. You will irrigate for long periods as opposed to flushing a toilet 15 times per day. You can then get by with a fairly small diaphragm pressure tank, so you will save a lot of space and maintenance vs the old galvanized tanks you have now.

Thanks for the input, reach. I didn't know these existed until Googling around last night. If I understand how they operate, device would need to be in line between pump and backflow valve...correct?

 

[Reach4]

The only check valve that should be in the system before the pressure tank and the pressure switch is the one down-hole at the top of the pump. There are some places that call from an above-ground check, but it is better to not do that. So CSV would go just before the pressure tank. http://www.cyclestopvalves.com/simple/home.php There is a pressure tank+CSV combo available. http://www.cyclestopvalves.com/prod_psidekick.html I will leave it to Valveman to make a specific suggestion. He would probably want to know what GPM flow you might do. You said the pump was 3/4 HP, but you did not say how deep it is to water and to the pump. The HP and depth to the pump can let you estimate pretty well what GPM the pump does.

Now one area where a topside checkvalve is needed is with a system with those galvanized tanks like in your photo and where the air comes from a down-hole bleeder valve. The way that works is when the pump shuts off, water is drained from a valve in the drop pipe and air is admitted up top from a valve called a snifter valve. Then the next time the pump starts, it drives a dollop of air up into the tank. There would be an air release valve on the side of the pressure tank to get rid of extra air. If that is what you have, you would want to probably get rid of that drain valve and snifter valve if switching to a diaphragm type pressure tank. Check with others. I am not a pro or even an amateur well worker.

 

[Carbidetooth]

The only check valve that should be in the system before the pressure tank and the pressure switch is the one down-hole at the top of the pump. There are some places that call from an above-ground check, but it is better to not do that. So CSV would go just before the pressure tank. http://www.cyclestopvalves.com/simple/home.php There is a pressure tank+CSV combo available. http://www.cyclestopvalves.com/prod_psidekick.html I will leave it to Valveman to make a specific suggestion. He would probably want to know what GPM flow you might do. You said the pump was 3/4 HP, but you did not say how deep it is to water and to the pump. The HP and depth to the pump can let you estimate pretty well what GPM the pump does.

Now one area where a topside checkvalve is needed is with a system with those galvanized tanks like in your photo and where the air comes from a down-hole bleeder valve. The way that works is when the pump shuts off, water is drained from a valve in the drop pipe and air is admitted up top from a valve called a snifter valve. Then the next time the pump starts, it drives a dollop of air up into the tank. There would be an air release valve on the side of the pressure tank to get rid of extra air. If that is what you have, you would want to probably get rid of that drain valve and snifter valve if switching to a diaphragm type pressure tank. Check with others. I am not a pro or even an amateur well worker.

Around here, all sprinkler systems require backflow prevention valves, which I is what I was showing photo. Well head is under that funny steel cap to the right. Pressure tanks are under the house about 30' away. I read up on CSV and if I'm getting it right they regulate flow via choking the supply line which I don't have easy access to in this case. Imagine a T coming off well and one leg going to sprinklers and other going to pressure tanks. Problem is tee is buried but the tanks are easy to access, so unless I'm missing something, I don't see where the CSV could go in this system and be effective.

I may call them Monday to clarify. It looks like an great solution if it can be made to work.

 

[Valveman]

Thanks Reach. We have CSV's that fit inside the well, so that any hydrant or tee at the well head is controlled. It may not be a DIY job as the pump has to be pulled up a few feet to install it. But if you have a bleeder in the well to add air to those old galv tanks, you may need to pull it up to plug that anyway as they are not needed with a bladder tank set up. Then you could add the CSV in the well at the same time you plug the bleeder.

 

[Carbidetooth]

Thanks Reach. We have CSV's that fit inside the well, so that any hydrant or tee at the well head is controlled. It may not be a DIY job as the pump has to be pulled up a few feet to install it. But if you have a bleeder in the well to add air to those old galv tanks, you may need to pull it up to plug that anyway as they are not needed with a bladder tank set up. Then you could add the CSV in the well at the same time you plug the bleeder.

No bleeder on system. It looks like the path of least resistance is sticking with pressure tank, but bladder style. I've located a 52 gallon tank locally that will fit...just barely, a Reliance PMD-52. I calculated volume of existing tanks at 45 gallons ea. for a total of 90 gallons. Using chart provided by Reliance, this would call for their 52 or 65 bladder style depending on pump output. Problem is, the 65 won't fit in space.

My plan is to install the 52 and give it a go, if pump short cycles, I can add an additional tank to that...perhaps 20 gallon.

Does that sound reasonable?

 

[Reach4]

With diaphragm/bladder tank, the drawdown (search for that term) is about 25% of nominal size. With the older pneumatic tanks, it is significantly less than that for a given size. So you may have about the same amount of cycling that you did in the past. Or you may have more or less.

Also search for precharge while you are at it. That is the air pressure in the tank when it is empty. Usually that gets set 2 PSI below what the cut-in pressure for the pressure switch. That gives the pump time to deliver water before the pressure tank totally runs out of water.

 

[Carbidetooth]

With diaphragm/bladder tank, the drawdown (search for that term) is about 25% of nominal size. With the older pneumatic tanks, it is significantly less than that for a given size. So you may have about the same amount of cycling that you did in the past. Or you may have more or less.

Also search for precharge while you are at it. That is the air pressure in the tank when it is empty. Usually that gets set 2 PSI below what the cut-in pressure for the pressure switch. That gives the pump time to deliver water before the pressure tank totally runs out of water.

Roger that, Reach4. I appreciate your guidance.

 

[Valveman]

It would tank three 119 gallon size bladder tanks to deliver 90 gallons of draw down. And larger tanks only reduce the cycling, they can't eliminate it like a CSV does.

Also you can use that sprinkler line in front of a CSV as long as the sprinklers output always matches the maximum output of the pump. You are going to need to match the sprinklers to the pump even with big pressure tanks to keep the pump from cycling to death. If the sprinklers are matched to the pump, you could put the CSV after the sprinkler line and would then only need a 4.5 gallon size pressure tank.