After spending a good bit of time on the web for this last night, I believe it's may increase my flow a small amount, but not much. And not to count on it.

 

One final update on this post for anyone who might find it while searching out the same thing.

I've consulted with a few pump distributors/manufacturers and determined that no, in my situation a booster pump will not boost flow (gpm).

The tutorial says a booster pump may increase flow, and reminds us in that portion that along with more pressure comes more flow. That, I believe, is talking about situations where you have more gpm available from your water source than you are using with your heads. I think it's reminding us that, if we boost the pressure, and more flow is available from the meter, that you're going to get more flow out of your sprinkler heads. Nozzle changes may be necessary.

I wish that part of the tutorial had been more clear, but I believe that's what it means when it says a booster pump "may" increase your flow as well. It can't change or boost our available flow, but it can potentially boost the flow put out at the end of the line as compared to what it was putting out at a lesser flow. IF there is more flow available pre pump than you were previously using.

I think in my situation, I would want a large tank supplied by my water meter, and a pump from there if I was really serious about boosting flow and pressure. Then, if my tank and pump were sized properly, I could get whatever flow and pressure I like, within reason. The tank would be refillled at a rate of 7.5 gallons per minute, so I'd have to calculate how many gpm my system would use, compare that to the refill rate, think about how long I'm gonna want to run my zones, and use that to determine what size tank I'd need.

I think I'll just make it work with 7.5 gpm flow and 32 psi 😂😱. I've come up with a rough plan on paper and I think I can make it work just fine.

 

What does your utility say? They may have a rule requiring their approval before you install a boost pump, and may know if you have more flow available. Then again, if you just design you system for what you have then you won't have to worry about pump maintenance in the future...

 

I could have a 1" tap and a 1" meter installed like next door, but I feel like $1500 for 10 gpm vs 7.5 is not worthwhile. Other than that, they basically said it is what it is. Since a pump wouldn't increase my flow, it's not really beneficial anyway.

As to this part,

"Then again, if you just design you system for what you have then you won't have to worry about pump maintenance in the future..."

Yes I agree. Except Stryker's guide states a few times that you need at least 50 psi design pressure for a rotor head irrigation system.

This is the reason for my asking questions on whether that's a hard rule or not. I think I could carefully put the system together and still deliver 20-25 psi to the sprinkler heads, and the charts do list performance data for that pressure, so I don't see why it won't work. I just haven't had anybody answer those questions yet so I'm not sure.

The reason I started looking at boosting pressure bas because of that statement in the irrigation tutorial.

 

Yeah, that make sense regarding the pressure for the sprinklers. I suppose you would have to know what the city pipes look like to be sure, but it sure seems like a pump would increase your pressure and flow. A 3/4" meter should be able to handle more than 7.5 gpm.

 

I have a hard time wrapping my mind around the physics of how it can possibly increase the pressure and NOT the flow. But two pump manufacturers I've consulted with both told me the same thing.

I have a 3/4 meter, let's pretend the piping behind the meter is also 3/4 (I'm sure it's larger though). 3/4 pipe can flow at least 20 gpm just fine.

Anyway, when I was on the phone with the guy over the town water, he kept just telling me "what you do with an irrigation system is, you just use smaller nozzles".

Well I know that but eventually they're so small my heads are misting and it also has to run forever to put down enough water. 🤦🏼‍♂ I just said yessir I know, since he was talking to me like he was schooling me up and 32/7.5 is just fine.

Through the course of our conversation, when I was picking his brain about whether my pressure is typical for our street, and whether he can increase it any, I did say a couple of times "I know I can use a booster pump if I have to to help me" and he never said anything about me not being able to.

So, I didn't "ask" him, but I mentioned it and he didn't say no.

At any rate, after crunching numbers and sketching this out, I'm thinking if I continue to use 2" and 1.25" pipe, I can deliver AT LEAST 6 gpm to the zones, and 20-25 psi to my heads. I really think I can work with that, and 20' spacing between heads fits into each portion of my property really well. I think it came out to 10 zones, and I just so happen to have a 12 zone Rainbird controller with only 2 zones in use now!

 

That's lucky about your controller. Big caveat, I'm not an expert, but the way I understand it, the pump increases the energy in your system, but total energy includes dynamic pressure (static psi) + flow energy (gpm). So if you are using a pump, the more flow you use, the static pressure goes down. The pump should come with a pressure/flow curve chart that would show the relationship, like this:



So, IF there was enough water behind your meter to handle it, I would think the pump line labeled 'MQ 3-45' would give you around 48 psi at 7.5 gpm, and 38 psi at 12 gpm. But that is assuming a starting pressure of 0 psi, and you have 32. I'm not sure if the psi increase would be additive, or if the pump just maxes out at that curve.

The total energy that the pump is able to add can't really change, that's why psi goes down (energy in the form of static pressure) as gpm goes up (energy in the form of dynamic pressure), though it probably varies a bit due to changing efficiency.

But I don't know what's behind your meter. If it's just a few feet of 3/4" pipe connected to a much bigger supply line, then I would think there is a lot of water for you to pull from. For instance your 1" metered neighbor is getting 10 gpm, probably also at 32 psi. I would think you can increase your overall energy and get that same 10gpm. Maybe if you're not happy with the pressure/performance once your design is complete, you could go back and add one.

Maybe someone will eventually come on and give a boost pump 101...

 

Yes, next door is also 32 psi. His irrigation meter, my house meter, and my irrigation meter are all 32 psi. Both of mine give me about 7.5 gpm.

The boost pressures are additive. I do know that. So, I would search for a 20-30 psi pump at whatever gpm I thought would be sufficient.

I think I can make the new irrigation I want to run work fine as is.

But there are two existing zones both using 6 Rainbird 5004 rotors. I'm afraid when I tie my meter to those it may not drive them very well. If that is the case, I may want to look into boosting just those two zones. If I tie in and I can adjust some nozzles and it works okay, I'll be golden. I think.

 

Yeah, your utility company is not doing you any favors, that pressure and flow is really low. Double check all you pipe pressure loss for all your runs. I would design it to have negligible loss everywhere. I wouldn't even accept a 1 PSI loss... Then again I really over designed my own pipes, I guess that's just what I do.

 

That's what I've done. 2" mains, 1.25" laterals.

According to the charts 1.25" mains would be negligible, almost non existent losses too.

 

I'm also curious about booster pumps (And potentially flowing water into a tank and pumping it out) for a slightly different reason than you, but related. I have about 25k sq ft of irrigated lawn on 21 zones. It takes my system nearly 11 hours to run through all the zones and put out 0.50" of water. I have considered breaking my watering into 2 programs to split the watering in half and just running the programs on different days. 11 hours to run the entire program will break the recommendations one way or the other. I have to chose between starting at night to finish in the morning, or start at dusk to finish in the evening.

 

I'd like one for my house also. 7.5/32 at the meter, and my main line is 3/4 pex about 85' long. I had great water pressure at my old house. Comparatively, our showers suck 👎🏼.

 

3/4 PEX for 85ft is a problem. 3/4pex is like 1/2 copper.

 

I know.

 

Your house water is 7.5 gpm at 32 psi, and from THERE it has to go through 85' of 3/4 pex? That is not good.

I had a water softener loop put it and the plumber said he would size the pipe as necessary. He put in 3/4" pex. I made him redo the work and increase the size by showing him the pressure loss table. I was losing more pressure from that pipe run (almost 100') than from the water softener itself. Absurd. But I was starting with over 50 psi, not 32...

 

Yep

I dug down and tapped into it about 10' past the meter and added a spigot there, and and that spigot I get 7.5 gpm.

The other spigot I have at the end of my main line, before it branches into the house, gives me 5 gpm.

The house is sufficient ish though. It is what it is, I'm not going through the trouble to replace that main any time soon. It's not off the radar, but it's near the bottom of a list of priorities though.

 

Well, they ran me a larger supply line. Which I'm extremely grateful for. They certainly didn't have to do that, I didn't ask them to. The last time we talked he said he'd "see what he could do to make it better for me". I certainly didn't think that would mean running me a larger supply line like this. Not when my flow/psi was already acceptable. Marginal, but acceptable. And it's not like I was raising Cain (as my Momma says) about it.

Anyway, I don't know EXACTLY what they did, but he told me he thought I was "on a small line over there" when I talked to him last, and he might be able to get me on "the big line". I'll call tomorrow and thank them and ask exactly what was done.

So, I have a small improvement. I still have 32 psi, but previously it took me 40 seconds to fill my 5 gal bucket (7.5 gpm), now I can fill it in 35 seconds, which is 8.5 gpm.

This is a marginal increase, but even so does give me slightly more flexibility with either nozzle choices, or number of heads. Especially in my zones with few or no 360° heads.

 

Hey, that's nice of them! Every little bit helps when it comes to your sprinklers...

 

That's calls for hand delivering a case of cold beer. Maybe the booster pump can help you.

It's been more than 15 years since I took a fluid dynamics/thermo class. I know we discussed booster pumps. Impeller vs piston made a difference, I just don't recall.

 

That's calls for hand delivering a case of cold beer. Maybe the booster pump can help you.

It's been more than 15 years since I took a fluid dynamics/thermo class. I know we discussed booster pumps. Impeller vs piston made a difference, I just don't recall.

I think Froude and Reynold's numbers are involved, I'm fairly certain I never understood those.

 

I guess if we were near the maximal flow of the meter, main line, or supply piping it would make sense to me.

Since I'm not, and not even close to it, it seems toe that a pump would pull more gallons through in a given period of time.

However, both experts I've talked to told me they will not.

I'm not sure if that's ALWAYS true, or if it's possible under specific circumstances, and they state that a pump will not increase flow to protect themselves and not give someone expectations that may not come true.

In their eyes, perhaps, most of the time flow is closer to the max of the pipe, and if they go around telling folks a pump can increase flow, and it doesn't, a customer may be upset about it.

I don't know. I do believe that I can achieve my goals without one, though.

 

I've sort of come full circle on this. I'm certain these days that I can't increase flow, I've got that.

I'm not, however, as certain as I used to be that a pump won't help me.

I was thinking of using 3500 rotors at 20' spacing, which works out really well with the dimensions of my property. I would set my zones up for 6 gpm. 2-3 heads per zone depending on how the shape is and the arc needed there. I have 40' between my house and the road, so 20' spacing works really well, and falls into place pretty well when I round the corner onto the side yard as well.

After studying the charts some, it looks to me like if I add a +20 or +30 psi booster pump, I can use 5004 rotors with 40' spacing. This simplifies my plumbing a little, eliminates a few heads, and will actually help me eliminate a zone or two, and save a little money on pipe/valves. I'd still set the zone up for 6 gpm, but if I can get 45 psi to the heads I can use 40' spacing. I think.

Thoughts here? I'm having trouble looking through websites online and finding a pump that's only +20 or +30 psi at around 8 gpm.

 

After studying the charts some, it looks to me like if I add a +20 or +30 psi booster pump, I can use 5004 rotors with 40' spacing. This simplifies my plumbing a little, eliminates a few heads, and will actually help me eliminate a zone or two, and save a little money on pipe/valves. I'd still set the zone up for 6 gpm, but if I can get 45 psi to the heads I can use 40' spacing. I think.

Thoughts here? I'm having trouble looking through websites online and finding a pump that's only +20 or +30 psi at around 8 gpm.

Tested some 40' spacing with 5004's and even the slightest breeze significantly impacted the max throw distance of my rotors. YMMV.

My reliable pattern was 25-30' on 5004's. Just my experience.

 

And that was with ample flow to match whatever pressure you had?

If so, that seals the deal I think. I'll stick to my 20' spacing and 3500 heads. Thank you very much!

 

After studying the charts some, it looks to me like if I add a +20 or +30 psi booster pump, I can use 5004 rotors with 40' spacing. This simplifies my plumbing a little, eliminates a few heads, and will actually help me eliminate a zone or two, and save a little money on pipe/valves. I'd still set the zone up for 6 gpm, but if I can get 45 psi to the heads I can use 40' spacing. I think.

Thoughts here? I'm having trouble looking through websites online and finding a pump that's only +20 or +30 psi at around 8 gpm.

Tested some 40' spacing with 5004's and even the slightest breeze significantly impacted the max throw distance of my rotors. YMMV.

My reliable pattern was 25-30' on 5004's. Just my experience.

I have similar thoughts. I have one area where I have 45' spacing with 5004's on a 90 and have trouble on windy days. I like the 20' spacing with the 3500's where you may be able to employ a little better overlap.