2 Booster Pumps, Same Mainline

[GaryQWA]

</font><blockquote><font class="small">In reply to:</font><hr />
Uniform pressure thoroughout ANY piping system is only possible if the velocity is ZERO. Under any other flow conditions, there will be variations in pressure; between user and first storage tank; between first storage tank and second storage tank; etc., etc. It's just like one of those "Balancing Reservoirs" excercises from Venard's: "Fluid Mechanics and Hydraulics"

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You'll have to forgive me, I'm not an engineer, I'm just an old guy that works on well water systems with a fair troubleshooting and mechanical hands on ability. [img]/forums/images/icons/wink.gif[/img]

Actually, the velocity IS ZERO before he opens a tap, and the switch and guage at the pumps will show/sense the pressure drop as the water exits the tap, unless there are check valves on the line from each pump to the tee tying the two tanks system together. Then the pump with the shortest distance should see it first.

Yes he will have a dynamic pressure loss due to the friction loss in the line and any fittings and dynamic pressure is different and less than static pressure but again, the switch and guage on/at each pump will see EITHER type pressure decrease with the tap opened. I'm sure you will agree with that or we'd be talking about how to get the pumps to run when needed...

Also, I see him using a submersible pump in the tanks OR a jet or centrifical pump outside the tanks with flooded suction. For general discussion purposes (again), the pumps are going to pressurize the system, not the water in the tanks. The switch and guage will be outside the tank and on the service side of the system, not on the tank side.

Additionally, his system is far from being "balanced" because of hundreds of feet of 2" pipe! And I can see many service line joints at least every 20' if the system is using anything other than PE tubing. AND he says there are various valves tying the two tank system together.

Also recall that as yet we don't know of any elevation variance between the tanks. Nor do we know if there are any check valves in the system; which certainly cause an imbalanced system between these two tanks. So IMO a "balanced" system is out and there is no possible way to balance it as designed and supposedly already installed plumbing.

BTW, because Cycle Stop Valves provide constant pressure (controlled at the pump outlet), I'm fairly sure that Cycle Stop Valves would tend to balance flow and user end pressure. And that goes to the original subject/question "2 Booster Pumps, Same mainline". One pump, the one with the longest line to the mainline, will have to be larger in GPM and possibly hp, than the other UNLESS or UNTIL we plug in a negative elevation to the tee to the mainline. Is that right or wrong?

Gary Slusser

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] SLO's system is NO DIFFERENT than a city water system with multiple wells and multiple tanks, except that they would usually have a variable speed drive on at least a percentage of the pumps. If SLO is pumping out of atmospheric storage and trying to go straight hydraulic with the system, it won't work. SLO will need some hydropneumatic storage somewhere in the system, and the more the better. I don't think anyone said anything about SLO's system being "balanced". I referred to the "Balancing Reserviors" excercise because it embodies the same kinds of engineering considerations that SLO's system has; various pipe lenghts; some possible elevation differences; and mulitple sources. I cannot see where he would need anything except some decent-sized pressure tanks on the discharge side of the pumps; good intake check valves for the pumps; and MAYBE a pressure switch dampener to reduce the effect of "pump-on" pressure spikes on the cut-off settings of the switch. Oh, and one more thing.....some way to restore the air charge in those hydropneumatic tanks........unless they are bladder tanks. [img]/forums/images/icons/tongue.gif[/img]

[SLOBuds]

Both of you guys are way beyond me.

But just to fill out the system a bit, for info, there are indeed 2 pressure tanks on the system as well. I guess I should have mentioned that. The tanks are positioned with each of the pumps.

Yes - varying pipe lengths. Yes - slight elevation change.

I don't know if there is or will be a pressure switch dampener.

The prospect of having a redundant system makes me happier as I think more of it. A problem with of them will leave me with water as I wait for repairs.

Martin

[Pat]

Don't everyone get mad at me at the same time but this is quite a collection of answers/responses varying from potentially well intentioned but sadly misinformed to preyy good.

Here is my contribution to the confusion:

It doesn't matter which pump comes on first or that the pressure switches are perfectly synchronized. If the first pump to come on doesn't produce enough water to satisfy the demand the pressure will drop and the other pump will come on and help.

Check valves in the output of each pump can help stabilize the system against oscillations. You do need to give consideraton to hoiw you distribute, size, and locate pressure tanks. To avoid a long winded and probably confusing lecture on that topic, instead I'll recommend that you contact a reputable manufacturer of well equipment and get a recommendation. Telephone numbers for well pump manufacturers customer care lines are often on the box or in the manual of a well pump. Go to a farm store and copy the number off a new pump. I got quite an education a few years ago that way. There are lots of wrong ways to plumb multiple pressure tanks.

[img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] Pat, it seems like SLO has everything that he needs if there is a hydro-pneumatic tank at each pump. He has, in fact, duplicated a typical multi-source water system just like the cities have, but smaller. The pressure switch arrangement of which you speak is the "lead-Lag" type of arrangement where the lead pump pounces on the demand and if that doesn't do it, .......that is to say pressures continue to fall.....the lag pump comes in. When demand goes away, the the lead pump shuts off first and the lag pump shuts off as pressure continues to build back up. [img]/forums/images/icons/tongue.gif[/img] After having spent thirty years in the pump business, I can only tell you that it might be tough to get real knowlege about applications in a farm store; it's tough enough to find dealers who know what they are doing. Years ago,; before I owned my own dealership; I was chief of applications for a major pump manufacturer and spent my days trying to keep our dealers from doing the wrong thing. [img]/forums/images/icons/crazy.gif[/img] One small note, however,......in atmospheric booster pump applications, if you have the check valve on the discharge side, there is a chance that the pump may not be able to make the head needed to push it open if the volute has an air pocket in it. For that reason an intake-side check is actually a better way to go; not absolutely essential, just a safer way to do it. [img]/forums/images/icons/tongue.gif[/img]

[egon]

Pat:

Some of us just call it water hammer. With no check valves think one tank just may overflow. There are damper systems that can be placed in line and other ways of reducing the hammer.

No one seems to have considered the output versus demand, line size, bends etc. Could be just a little factor to consider in design.

The pressure guages we usally see on home water systems are not too sophisticated. A good instrument teck could install a pretty nice set of controllers/ gauges that have quite a few more features.

With two pumps comming on line at different times, which they will with just Hi/Low switches, could end up with a continuously cycling system. Interesting?

Egon

[GaryQWA]

Martin, swerving off in another direction... there's quite a bit of info we don't have.

Like how you fill these tanks. Where the pressure tank/s are located in relation to the tanks. Where the pressure switch/es will be located. The primary use of this water. The volume of water to be used in peak demand gpm. The pressure required where the water is to be used. The elevation of the highest water use measured from each pump. The power source for the pump/s and the distance to the pump/s. The guage of any power cable already run. The size and type of pump/s you want to use (I presume that's why you posted here). The type of material used for the 2" water lines and the length of individual sections, or between coupler fittings; I.E. 21'. The type of stop valves used. Will there be a problem with the use of water from one tank more than the other? Are there check valves anywhere and if so where?

You need all that info to be able to design a system that will work and/or to select the size and type of pump/s.

If this were my water system, I would like one source that is proven capable to provide my needs, and I'd want it close to where I use the water. I would want to use a submersible pump. I would control that pump from where I use the water; that's where the pressure tank, guage and switch would be unless I could use a Cycle Stop Valve then the tank and switch would be at the water source. That would allow me to use a very small pressure tank as opposed to a very large one to keep my pump motor properly cooled between start ups; off for at least 60 seconds for up to 1 hp and 120 seconds for 1.5 to 2 hp. I would use float switches in any atmospheric water storage tank to prevent the submersible (or other type) pump from being able to run dry, and/or to control another pump in a well used to refill the tank. If the refill water was from a truck delivery, I'd want some means to tell me when I needed to refill it that prevented me to have to physically go look in the tank. If I had two storage tanks with a pump at each, I'd have a check valve on the outlet of each pump.

That type system is used anywhere around North America where needed and (some) well drillers and pump guys do it daily.

Gary Slusser

[CJDave]

[img]/forums/images/icons/crazy.gif[/img] SLO has a very routine and common application here, and I doubt of any of the multiple difficulties mentioned will actually plague the system; except possibly the actual setting of the pressure switches; but that is a one-time thing. I could not even count the number of these kinds of systems I have seen and installed for everything from a summer camp to a subdivision. Atmospheric-storage-with-booster-to-mainline......that's pretty routine, whether it has one source or ten sources. He should be fine with it. [img]/forums/images/icons/tongue.gif[/img] [img]/forums/images/icons/tongue.gif[/img] IF IT WAS UP TO ME..... [img]/forums/images/icons/tongue.gif[/img] [img]/forums/images/icons/tongue.gif[/img] [img]/forums/images/icons/tongue.gif[/img] [img]/forums/images/icons/tongue.gif[/img] I would set it up with the two remote sources pumping into the common mainline feeding an atmospheric storage tank at the point of demand("the ranch"), and radio control the on-off using a float switch in the atmospheric tank. That way your transportation line is at low pressure and runs for long periods to refill the reservoir with both pumps on the line at the same time. There would be no discharge-side tanks at the junctions of the source pumps and the mainline, just check valves for preventing backflow in the event of a failure of one pump. The benefit of this method is the greater instantaneous flow available at the point of demand since it would be taken from the reservior(tank) that is kept full by the two remote source pumps. It's just a little better way to go and leaves less machinery in the far flung areas to look after and maintain. [img]/forums/images/icons/tongue.gif[/img] So to recap.......two source pumps pumping into the low pressure main......main fills big atmospheric storage tank at "the ranch".....float switch signals source pumps to start and stop.......booster pump pulls out of big atmospheric storage to pressurize "the ranch". [img]/forums/images/icons/crazy.gif[/img]

[Pat]

Dave, OH NO NOT REAL EXPERIENCE!!!! Lets just conjecture about the number of angels that can dance on the head of a pin and not ask any angelic dance instructors! I agree completely with your analysis and bow to your superior experience as regards the location of the check valve.

I have telephone access to a pump guru at Federal Corp in Oklahoma City. That is where I buy my pumps. Latest application is a pump to recirc potable DHW through a flat plate heat exchanger and a 50 gal electric DHW tank with no electrical connection to the heating elements. I will connect the tank's thermostat (make on temp fall) to energize the pump. The other side of the exchanger is circulating hot water through a ground sourced heat pump and a 30 gal DHW tank with glycol solution. Trying to preheat my DHW for about 1/3 the cost of a standard DHW tank.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] It's complicated but I'm getting it....I'm on it. [img]/forums/images/icons/tongue.gif[/img] The DHW tank is for storage and for the temp sensing function. [img]/forums/images/icons/tongue.gif[/img] The GSHP shaves the first 30-40 degrees off the water. [img]/forums/images/icons/tongue.gif[/img] [img]/forums/images/icons/tongue.gif[/img] Did you see that HW heater that was noted in that other thread? The one about one HW heater or two? I was kind of confused about how that setup would work in cold weather if it is inside an equipment room? [img]/forums/images/icons/crazy.gif[/img]