Urgent Well Pump Question

[_RaT_]

The HP demanded by the pump will depend on more then just your GPM. The depth of the well and the height of the water in the well (head pressure) will determine not only the size HP but the number of stages the pump will need to get the water to the top and then pressurized to the pressure you want, typically about 45 to 50 PSI. For every 2.3 feet of height you need one pound of pressure just to lift the water or put another way, a column of water 2.3 feet high will exert 1 PSI pressure at the bottom of the column.

The pressure tank has almost nothing to do with storage but simply a means of keeping pressure on the plumbing system via a compressed volume of air. The larger or more pressure tanks you have, the longer you can flow water before the pump kicks back on to get back to your desired pressure. Cut in and cut out pressures typically vary by about 10 PSI. To get extra fancy and have a constant pressure you can get a special pump set up on a frequency drive that will spin the pump at the speed necessary to match your flow rate that will maintain a constant pressure. I use large frequency drives on 3 phase pump motors exclusively. I do not know how well they work on home type models but have heard some bad comments about them in the past. Check Franklin for some ideas.

 

[Bikewanderer]

The HP demanded by the pump will depend on more then just your GPM. The depth of the well and the height of the water in the well (head pressure) will determine not only the size HP but the number of stages the pump will need to get the water to the top and then pressurized to the pressure you want, typically about 45 to 50 PSI. For every 2.3 feet of height you need one pound of pressure just to lift the water or put another way, a column of water 2.3 feet high will exert 1 PSI pressure at the bottom of the column.

The pressure tank has almost nothing to do with storage but simply a means of keeping pressure on the plumbing system via a compressed volume of air. The larger or more pressure tanks you have, the longer you can flow water before the pump kicks back on to get back to your desired pressure. Cut in and cut out pressures typically vary by about 10 PSI. To get extra fancy and have a constant pressure you can get a special pump set up on a frequency drive that will spin the pump at the speed necessary to match your flow rate that will maintain a constant pressure. I use large frequency drives on 3 phase pump motors exclusively. I do not know how well they work on home type models but have heard some bad comments about them in the past. Check Franklin for some ideas.

Most home consumption is either on or off. You can't run a VFD much lower than 20hz anyway - little to no advantage in a home type application. You also run the risk of overheating the motor as such low speeds.

 

[_RaT_]

That all depends on where you live. If your in the West, you irrigate all the time. They are far more popular here I suspect than back East where your demand is pretty much for domestic purposes with relatively low flow rates. Here, not unusual to have at least 10 GPM to 100's GPM if you can get it. The pumps I maintain supply our small community with irrigation and fire hydrant water with a capacity of about 1300 GPM @ 50 PSI. They are staged to kick in as demand increases and sleep as the demand falls off.

Heres a link with a little more info... http://www.envisupply.com/equipment/constant_pressure_pump.html

Most home consumption is either on or off. You can't run a VFD much lower than 20hz anyway - little to no advantage in a home type application. You also run the risk of overheating the motor as such low speeds.

 

[crazyal]

I may be a little late here but the pump HP tells you very little. Pumps are rated in both GMP and HP. You're well driller should be able to size the pump up for you. To figure out the correct size of pump needed you'll need to know the depth the pump will be placed in the well, the make up of the well, and the total height the water will need to be pushed (the low point being where the pump is located in the well to the highest fixture in the house).

The depth of the well will be determined by the the size of the house (potential water demand), any other water useages, and water make up rates as he's drilling. After he drills the hole and has the correct water make up rate he then can size the pump. Around here the drillers have a supply of pumps and will choose as needed. As a rule of thumb the higher HP the more it will cost and the lower the GMP of the pump the more it will cost (more stages). Secondly the larger the HP the larger the wire size needed for the pump.

To answer your question a 1hp may be needed or it could just be extra cost for nothing gained.

 

[dcyrilc]

To get extra fancy and have a constant pressure you can get a special pump set up on a frequency drive that will spin the pump at the speed necessary to match your flow rate that will maintain a constant pressure.

A cheaper and simplier means to regulate a constant pressure for residentual use is to simply install an adjustable pressure regulating valve on the output from the system to the house. They are typically set just a few PSI below the cut on pressure of the well system.

 

[_RaT_]

I have used them. They are pretty slick. Hard for folks to understand how they work, but they do work and they are relatively cheap. Flow control valves basically pinch off the output side of the pump as the pressure gets closer to the cutout. When you do that, you knock the current down on the pump. I have watched the current or amp meter drop as the flow control slowly chokes off the output. That would be a nice option for folks to consider. I did a quick Google of flow control trying to remember the company I used in the past. They were out of Texas.

Just remembered, http://www.cyclestopvalves.com/techq_8.html

A cheaper and simplier means to regulate a constant pressure for residentual use is to simply install an adjustable pressure regulating valve on the output from the system to the house. They are typically set just a few PSI below the cut on pressure of the well system.

 

[dcyrilc]

I have used them. They are pretty slick. Hard for folks to understand how they work, but they do work and they are relatively cheap. Flow control valves basically pinch off the output side of the pump as the pressure gets closer to the cutout. When you do that, you knock the current down on the pump. I have watched the current or amp meter drop as the flow control slowly chokes off the output. That would be a nice option for folks to consider. I did a quick Google of flow control trying to remember the company I used in the past. They were out of Texas.

Just remembered, Cycle Stop Valves, Inc.

I used something like this:
223, 223S High Capacity Water Pressure Reducing Valves, Water Pressure Reducing Valves - Super Capacity, Water Safety & Flow Control - Watts

It might have actually been this one. Not sure without looking it up. Used 1" size to meet my piping requirements.

Actually, I don't think it was this one as I was looking for one which went to a lower pressure and IIRC the one I got went down to 15 PSI.

 

[BrianR]

I love my Franklin VFD constant pressure system. I'll never go back to the old system of using a large bladder tank again. Well is 95 feet deep, yields 68 gpm and pump yields 32 gpm wide open off the pump discharge. I can finally run kitchen tap, bathroom tap, shower and laundry at the same time while running 2 sprinklers on the yard/garden.

The VFD seems to be easier on my generator as it spins up slowly and doesn't hammer then genset so much. Of course, clean power from the genset is essential with this system.

I agree with the others....wait til the driller is finished and see what he recommends. My well is in a huge gravel lense (glacial moraine where I live). I was expecting 200 ft or more to get through the limestone bedrock like some of my neighbors have.....but I got lucky.

 

[_RaT_]

I was wondering about that Brian, the ability to get a well pump going on a VFD, it has to be much easier to do especially if your generator is marginal. The VFD's I manage are very nice, two are Franklin. After using Cyclestop valves, I really like the simplicity of the 3 phase frequency drives I keep up. They are actually cheaper than the 6", 4" and 2" Cyclestop valves I would need. I'm would be inclined to do the same as you if I was on a well.

I love my Franklin VFD constant pressure system. I'll never go back to the old system of using a large bladder tank again. Well is 95 feet deep, yields 68 gpm and pump yields 32 gpm wide open off the pump discharge. I can finally run kitchen tap, bathroom tap, shower and laundry at the same time while running 2 sprinklers on the yard/garden.

The VFD seems to be easier on my generator as it spins up slowly and doesn't hammer then genset so much. Of course, clean power from the genset is essential with this system.

I agree with the others....wait til the driller is finished and see what he recommends. My well is in a huge gravel lense (glacial moraine where I live). I was expecting 200 ft or more to get through the limestone bedrock like some of my neighbors have.....but I got lucky.

 

[lllpatricklll]

Hello everybody! I'm new here.

Why abandon the well? If the old well is not in your way or otherwise poses no health or safety concerns, keep it and repair it later.
Use your new well for the house and use the old well to water your trees and garden. No sense using potable water on a tree. Tree don't care. And if your main well for the house ever stop working you'll at least have water for laundry and bath.

Just my opinion.
Have a great day!