plumbing query??

[nwcove]

a work mate of mine is replacing a well line.....from well pump to pressure tank. the pump discharge is 1". the contractor digging up the old line says he needs to go with 1 1/4" line? it doesnt make sense to me.....if the pump has a 1" discharge, what, if any, benefit would it be to adapt up to 1 1/4" ? seems like it would just cost more and throw the pump curve off??

 

[Grub54891]

Re: plumbing query??

Hmmm.... Might be the distance it has to run. Say an extension cord can handle-x- amount of amp's,the longer the cord,the more resistance, then you have to up the size of the wire to avoid voltage drop. So the longer pipe should be bigger to allow plenty of flow,even if the sorce is just a tad smaller,the pump won't have to work as hard to push the water through.
I'm shure someone will shoot a hole in my theroy.
Grub

 

[stackz]

Re: plumbing query??

how long of a run is the pipe from the well to the discharge?

whats the size of the pump? if the pump can handle it, the larger pipe diameter would help keep pressure at the discharge up higher longer. if the pump cant handle it, you'll lose pressure/prime.

is the guy adament about wanting to use 1-1/4" pipe and giving appropriate reasons?

 

[dingbat]

Re: plumbing query??

Water moving against the inside of the pipe causes friction. The faster the water moves (velocity) and the longer the water is in contact with the walls of the tube (length), the more friction is built up. The pressure the pump uses to overcome this friction manifests itself a drop in pressure at the discharge.

Example: at 10 gpm, a 1" diameter hose will cause a 3.4 psi drop in pressure for every 100' feet of hose. In comparison, a 1.25" hose will cause 1.1 psi drop per 100' feet. In a 400' run, you'll see a loss of almost 14 psi with the 1" pipe compared to a 4 psi loss in the 1.25" pipe. Might not seem like much, but the pump will be 4 time happier with the 4 psi pressure drop

 

[nwcove]

Re: plumbing query??

how long of a run is the pipe from the well to the discharge?

whats the size of the pump? if the pump can handle it, the larger pipe diameter would help keep pressure at the discharge up higher longer. if the pump cant handle it, you'll lose pressure/prime.

is the guy adament about wanting to use 1-1/4" pipe and giving appropriate reasons?

i believe he bought 200' of 1 inch line, i can only guess that the pump is 1/2 hp, and it is feeding a domestic pressure tank. cant answer the last question.

 

[nwcove]

Re: plumbing query??

Water moving against the inside of the pipe causes friction. The faster the water moves (velocity) and the longer the water is in contact with the walls of the tube (length), the more friction is built up. The pressure the pump uses to overcome this friction manifests itself a drop in pressure at the discharge.

Example: at 10 gpm, a 1" diameter hose will cause a 3.4 psi drop in pressure for every 100' feet of hose. In comparison, a 1.25" hose will cause 1.1 psi drop per 100' feet. In a 400' run, you'll see a loss of almost 14 psi with the 1" pipe compared to a 4 psi loss in the 1.25" pipe. Might not seem like much, but the pump will be 4 time happier with the 4 psi pressure drop

very interesting dingbat.....i didnt even think of friction loss. i was thinking more along the lines of velocity vs volume.

 

[Fishing Dude too]

Re: plumbing query??

Or he got a better deal on 1 1/4 line or all was available at the time

 

[calamus]

Re: plumbing query??

Almost every deep well pump has an 1 1/4" outlet if you ever up grade your pump you will want the bigger line This is the smallest standard size line for a home these days.

 

[generator12]

Re: plumbing query??

Water moving against the inside of the pipe causes friction. The faster the water moves (velocity) and the longer the water is in contact with the walls of the tube (length), the more friction is built up. The pressure the pump uses to overcome this friction manifests itself a drop in pressure at the discharge.

Example: at 10 gpm, a 1" diameter hose will cause a 3.4 psi drop in pressure for every 100' feet of hose. In comparison, a 1.25" hose will cause 1.1 psi drop per 100' feet. In a 400' run, you'll see a loss of almost 14 psi with the 1" pipe compared to a 4 psi loss in the 1.25" pipe. Might not seem like much, but the pump will be 4 time happier with the 4 psi pressure drop

Dingbat is correct. However, the only difference that would be seen in function is that the tank would take a bit longer to refill when calling for water. If the user's application doesn't actually outrun the pump's output, he won't even notice this. The pump would run longer during each cycle, but it wouldn't actually "work harder". Centrifugal pumps "work harder" when pushing high liquid flow rates - and the larger pipe would result in a higher flow rate than the smaller one. If the 1" pipe has been adequate to now, and nothing changes in the usage characteristics, it will be adequate in the future.

(I deal with piping systems in breweries. When dealing with beer, pressure drop is often a concern because of foaming, particularly at pump inputs, so larger pipes are generally preferred. But there is always the cost factor.)

 

[CharlieB]

Re: plumbing query??

If possible return the 1" and go with the 1 and 1/4, the pressure drop and reduced flow from the line loss will be much improved and the pump run time will be reduced, saving electricity from now on.

For the sake of argument, if a 4 " pipe was installed, the pump run time would still be within seconds of the 1 and 1/4. Once the pipe is filled it remains filled, water in equals water out. Line loss would be an absolute minimum by flow rate would remain the same as with the smaller pipe. Too bad water isn't compressible. Large pipe dia's are often used in air supply systems, either to run 'tankless', the pipe becomes the tank, or to increase reserve, in effect increasing tank size.

 

[ondarvr]

Re: plumbing query??

I used to build and install water filtration systems for irrigation, water parks, swimming pools, large aquariums around the world, etc.

In most situations larger pipe is better, you can reduce the pump HP and retain the same flow by stepping up in pipe diameter, there really aren't many downsides to it...within reason. The difference in price between 1 and 1.25" isn't much compared to the benefits.

I will be running new pipe for my well system very soon and even though it's shorter than this one I may go with 1.5"


PS. This is the case even if the discharge fitting on the pump is smaller than the pipe ID.