Irrigation booster pump question

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  #1  
Old 04-26-09, 06:51 PM
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Irrigation booster pump question

I'm hoping perhaps someone can help me out with some advice on installing an irrigation booster pump. I've read a few (probably more than a few) articles on the web but I'm still not sure of the best approach for my situation.

I'm preparing to install an irrigation system for a home that I just finished construction on and have done some irrigation system installations before so the "nuts and bolts" of installing the system are fine for me. In this case, however, I've got a situation where I know I'm not going to have enough pressure to effectively water the turf that needs to be watered. The home has a public water supply but the pressure is only at about 40 PSI static. The local water officials are unwilling to do much about it. So, at 40 PSI static I'm essentially sure that I won't have anything near great pressure once the water makes its way through the backflow, through the pipes, and ultimately up to the rotors that will water most of the turf.

I think the best solution in my case is to install some sort of "booster pump" to help give the water a bit of a boost on the way to the rotors. If possible, I'd like to install the pump outside so as to keep my basement (where the water inlet is) free of the pump. So, my questions (in no particular order) are:

Is it possible to install a booster pump outside (perhaps after the irrigation backflow preventer but before any of the zone valves?) to just boost the pressure of the irrigation system without impacting the household pressure dramatically? I certainly don't want to create big pressure drops or negative pressure inside if possible and know that I'll have to tap for the irrigation system in basement most likely.

If so, what type of pump should I be looking at and do you have any website or brand recommendations?

I'm thinking that I probably only need to add about 15 PSI to get where I need to be based on my system design so I'm guessing I don't need a particularly large pump? I know flow is also a factor and would guess that I'll end up at about 12 GPM for most of the zones.

Any help (or clarification on my thinking) would be greatly appreciated!
 
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  #2  
Old 04-27-09, 05:41 PM
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Location: Michigan
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you can put the booster pump outside and there is not a problem with that. Just make sure it its not designed specifically for inside use or put a "dog house" on it with plenty of ventilation so it does not overheat.

You probably only need a 1/2 HP booster pump and it does not need to be self priming.

The only downside I can see to installing it after the backflow device is that it may pull water too fast out of the backflow that it causes it to close, causing the pump to run out of water. I have never seen this happen myself, but it is possible. Every instance I have seen on installed, its before the vacuum breaker.

Be aware that some booster pumps for your static pressure can leak if they go below a certain PSI--so shop carefully. An irrigation supply house or online dealer may be able to help you find specifically what will work for you.

It sounds like you have a good handle on what is going on. I will say this, if its in an area that can freeze then inside is safest. Almost every booster I have ever come across is in the basement and only 2 models I have ever seen caused a problem in the basement (and its because of that low pressure problem under 40 PSI).

Most models never do that.


I would reccomend you install a pump start relay as your starting mechanism and use a clock/controller that lets you disable the MV on a zone by zone basis. If you dont know what that means, let me know.
 
  #3  
Old 04-29-09, 09:46 AM
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Thanks for the quick reply. I suppose it actually doesn't matter whether I put the pump before or after the backflow since the pump does the same thing regardless of which side it sits on. To be safe, I'll stick it before.

I think I understand your response regarding the pump start relay. If I'm right, you want the pump start relay so that you can allow the controller to tell the pump when to come on. In other words, no use in activating the pump and boosting the pressure for, say, the drip zones, where they're regulated down to 20-25PSI anyway. In those cases, the controller should activate the zone but not the pump... just let the water flow on through. For the zones that need the boost, link the big turf heads, then the controller should output a signal to the pump start relay to start up the pump and boost the pressure. This would also seem preferable to some of these "all in one" pumps that I've seen that have flow sensors and so forth attached to them to tell the pump when to turn on and off.

I'm going to call a couple of suppliers to get some ideas on brands and prices. I'll post something back for the benefit of the group once I better understand some options.

Thanks again!
 
  #4  
Old 04-29-09, 04:39 PM
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Location: Michigan
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Originally Posted by craigjl View Post
Thanks for the quick reply.

I think I understand your response regarding the pump start relay. If I'm right, you want the pump start relay so that you can allow the controller to tell the pump when to come on. In other words, no use in activating the pump and boosting the pressure for, say, the drip zones, where they're regulated down to 20-25PSI anyway.
Thanks again!
the quick reply was just luck - but thanks.. I check the forums every day or two now but I reply when I can.

Sounds like you understand the whole concept of the pump start relay. You dont need it to run when taking a shower, either.

Tap your house water line close to where it comes in. Switch right away to a 1" or larger line. Then put in your booster pump (unions are a good idea in case you ever need to repair it).

Basically the setup should go in this order:

1. water meter
2. Tee that splits off with a larger pipe headed for irrigation
3. shutoff valve for irrigation
4. union
5. pump
6. union
7. drain for irrigation can also go between 3 & 4.
8. line going to the outside.

Once you get outside I reccomend you install a pressure relief valve, pointed away from the house to a safe place. This way, if a valve never opens the pump will have a safe place to send the water if its running, saving your pump.
 
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