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The last 10 posts

Sunday, August 11th 2013, 11:50am

by Wet_Boots

There's enough elevation change to complicate things, relative to single-zone operation. As for controls and deadheading concerns, you might price a pressure switch and pressure tank in comparison to flow sensors. A tank and pressure switch don't have to be located at the pump. They could be next to the garage, or even inside. Do that, and you have a 24/7 water supply at any point as far as your mainline extends, and deadheading is no longer a worry.

Saturday, August 10th 2013, 11:29pm

by dharwood

This is the property layout. The lake is at the top (you can see the dock in the upper left). The white line is the property line. The yellow line is the boundary of the area I intend to water, with measurements in feet. The brown are the buildings and I also show the sidewalk and driveway. The thin black lines are elevation changes relative to lake level. Upper right red circle shows where the pump is and the red circle at the center right is where I intend to put the valve box and spigot, just outside the garage. Most of the property is flat with a small hill behind the house that isn't a huge priority to water.
My next step is to start to layout the sprinklers and calculate the pressure and volume requirements.


Saturday, August 10th 2013, 8:23pm

by dharwood

Ok thanks. That helps.

For lake water, it is pretty clean (can see the bottom at 12'). However it's clean because it's sandy so that is the biggest risk I think.

Even though it is one zone, I am planning on having the mainline end at a hose spigot with the sprinkler zone branching off just prior via a single valve. So dead heading would still be in play. I have decided to just go with the flow sensor on the mainline before the valve box. That way, when I open the valve and start the pump relay I can verify flow and shutdown if necessary.

When winterizing, do I need to blow the lines towards the sprinklers to clear the heads? Or can I just slope the lines and drain them with a ball valve on one end?

I do have the scale drawing (with the help of Google Earth), I just haven't tried placing sprinklers yet. I will try to upload to share.

Saturday, August 10th 2013, 7:35pm

by Wet_Boots

Sometimes holding prime can be a major problem. To some degree, it depends on the water entering the pump. With clean enough water, the check valve can function as intended, and all is well. Since I can't see the water, I'm trying to envision what might be done to help the check(s) hold prime.

Losing prime is going to be your only concern with a one-zone system, which won't have any zone valves that can fail to open. Deadheading is taken off the table as a worry.

It falls to you to make a scale drawing of the property, and the areas to be watered. There is no question that 60 gpm can fully cover an acre-plus of lawn, even if the heads have lower pressures. {the low-pressure champion of all rotor heads is the old-fashioned impact head, in the form of the Rainbird Maxipaw, which has design features and adjustments for low-pressure operation}

One wrinkle to a one-zone system, is that a 60 gpm system (your practical theoretical maximum) won't be easy to winterize, so it would configure in a way so that you could have manual shutoff valves close off sections, so you could blow out the lines one section at a time. These manual valves would also let you exclude wetter, shadier sections from full-time watering, if that would be desired.

Saturday, August 10th 2013, 6:44pm

by dharwood

I just wanted to start my project this year by tackling the mainline and getting the power to my pump buried underground. Knowing how many zones will change how I approach it, so the fact that I might be able do does this as a single zone was definately information that I hadn't conisdered. I had wanted to wait on doing the "math" on sprinklers until I was ready for that phase of the project, but now I realize I should probably have that information figured out beforehand. So that is what I am working on now.
Your last two post seem to be focused on holding prime, which hasn't been a problem. I certainly don't plan on buying a new pump since the one I have is brand new. What specifically is the disadvantage of a centrifugal pump in the configuration?

Saturday, August 10th 2013, 12:58pm

by Wet_Boots

One more note. If you were starting this from scratch, you use a different pump, like a Goulds jet pump. Jet pumps develop higher pressure, so you can plan a system more like what you'd have with city water. Goulds jet pumps have an inner diaphragm that keeps water in place around the shaft seal, and helps the pump hold prime.

Monday, August 5th 2013, 6:17pm

by Wet_Boots

Right now, the only thing that will keep the pump primed and ready to go, from one day to the next, is the check valve on the inlet side. If it gets fouled, or otherwise fails, water will drain back through the pump and you will eventually lose prime. You can always add another check valve on the upstream side, for the sake of redundancy.

The fact that you envision a long line running uphill from the pump, prior to it branching off, will give something for the pump to push against, and some weight of water pushing back on the check valve(s)

Sunday, August 4th 2013, 10:43am

by Wet_Boots

The only way you get the 88 gpm maximum flow from that pump is if the pump is about one foot above lake level, and the outlet is an open pipe dumping water on the ground (that is, an outlet pressure of zero)

If you go "old-school" with the sprinkler system, using impact heads capable of operation at 25 psi, you can get as much as 60 gpm to work with. You also skip the need for an additional filter or strainer, and the entire property can be covered as a single zone. Areas that might only need very occasional watering could be isolated from the system with manual shut-off valves.

You might work up a property diagram, with elevations. Lay out your system, add up the heads' water consumption, and see what you get.

Saturday, August 3rd 2013, 7:31pm

by dharwood

Ok, I was looking at the t-filter that I planned on getting..."Vu-Flow VFNT150-100P 1.5 inch 100 Mesh Polyester T-Style Filter". After reading the specs on it, I have my doubts about whether it will work in my setup. I was planning on putting it right after the pump outlet. The pump is basically pushing 80+ GPM at this point. The filter is rated for a maximum of 50 GPM on the 1.5" version.

The suction side does have a filter with a mesh matting.

Should I forego the filter? Get the filter, but ignore the rating? Or, should I get the 2" version,which is rated for up to 100 GPM, and just patch in a short section of 2" which inlcudes the filter?
Advice welcome!

Wednesday, July 24th 2013, 4:04pm

by Wet_Boots

I always try to have water uphill from the pump, in the system plumbing, if there isn't a pressure tank. Your terrain might provide that all by itself. Lacking that, the few feet of water in the pipe leading to the filter is better than nothing.

You have a classic centrifugal pump. It can move a lot of water. Instead of powering one sprinkler on the end of a hose, it could simultaneously power more than twenty standard sprinkler heads.

Note the performance data

at 100 feet of water, total head, it will pump 30 gallons per minute - 100 feet of water is 43 psi
at 80 feet of water, total head, it will pump 60 gallons per minute - 80 feet of water is 34 psi

You can see the value of preserving water pressure, if it can double the capacity (and efficiency) of the pumping

You do need to have your property elevations, relative to the lake surface, known and accounted for, when you work out a design.