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Alphas In Series

BigRob
BigRob Member Posts: 322
Has anybody tried installing two alphas in series? I'm thinking one alpha set to constant power, the other set to constant pressure. I'm looking for a cost effective ECM circulator in the 30ft head range.

Comments

  • Tom_133
    Tom_133 Member Posts: 884
    I have thought about this possibility a couple times. If you were to set them both for constant service it may work, but as you know it won't adapt for cost savings but they do both run at lower wattages and that may be cost effective. I think for the money and peace of mind, I would size a proper magna and set it for auto adapt. Of course that depends on what you are feeding if its just a loop no zone valves and you've done the math I would size a regular pump.
    Tom
    Montpelier Vt
    icesailorZman
  • BigRob
    BigRob Member Posts: 322
    I wonder if the second won't run properly. Hopefully some brave soul will try it. Looking at you, Hot Rod!
  • gennady
    gennady Member Posts: 839
    alphas in series
  • Zman
    Zman Member Posts: 7,569
    gennady said:

    alphas in series

    Why would you?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    icesailor
  • icesailor
    icesailor Member Posts: 7,265
    Putting two pumps in series like that, increases the available head pressure, but decreases the flow volume (GPM's).

    Like water pumps. Each impellor (stage) adds pressure at the expense of volume.
  • Ironman
    Ironman Member Posts: 7,373
    Just my country boy opinion here, but if you're gonna do this (don't know why), then both pumps should be on the same speed or gpm setting.
    I would go with the tool that's designed for it: the Magna, the Wilo Stratos or Taco's new Varidian properly sized.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • gennady
    gennady Member Posts: 839
    edited December 2014
    Second pump accepts discharge pressure of the first pump as a return pressure. Pressure of the 2 pumps doubles, but gpm stays the same. This is the system with single entry valves on some really big cast iron radiators (40+ sections), 180' pipe run and 9 gpm requirement. Considering high CV of single entry valve, long shoot of the water in the radiator and 15% pressure reduction of flow check, this was my attempt to find solution. I did not want to go away from VFD, and did not have a budget for Magna. Pump is set up for constant pressure, not for constant speed.
  • icesailor
    icesailor Member Posts: 7,265
    You're far smarter than I am.

    My experience with water pumps make me question that. If you have two pumps in series like you show, and you put three pressure gauges on the "train, one at the beginning and at the inlet of the first pump, one between the first and second pump, and the third gauge at the outlet of the last pump and turned them on, whatever the system static pressure is with the pumps not running should be considered zero, regardless of that the system pressure is. If it reads 12#, then ALL 3 gauges should read 12#. If you turn on the pumps, the first gauge will drop, but the middle gauge will be higher. If the first gauge drops to 9# but the outlet goes to 15#, you have 6# of head pressure. But the third gauge will NOT show 21# of head pressure.
    With well water pumps. the suction lift pressure always stays the same. If the lift is 10", it will always be 10" and if it goes lower, it is from well restriction. A single stage pump (one impellor) is effective to 50#. After 35# or so,, volume delivery drops off as the pressure rises, no matter what. Add a second pump, and the suction pressure will stay the same, but the volume outlet and pressure will rise, because the second pump doesn't need to add any negative (suction) pressure to the flow, but only adds pressure. Which will be proportionately to the volume of the first pump. But the volume increases. The difference is in the restrictions of the pumps.

    I'm not saying your scheme doesn't work. I'm only saying that if you expect another pump to double the output of a first pump, it won't. Proven with gauges. I've done it. I've seen it and how it works. They don't compound by "2". They compound by less than 2.
  • Ironman
    Ironman Member Posts: 7,373
    Two pumps in series = twice the head, same gpm;
    Two pumps in parallel = twice the gpm, same head ( approximately stated).

    I've got a job where I put two of them in parallel with both set to high speed just because the HO wanted to save some electricity. A power surge took out both them recently and he had to buy two more. I don't think he'll ever see a ROI.

    The Stratos is better priced from my experience when needing more than what a single Alpha can do.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • icesailor
    icesailor Member Posts: 7,265
    edited December 2014
    Read this pump curve chart from FE Myers water pumps.

    Read the chart for a HC50 shallow well single stage pump. It shows the different outputs at different suction lifts. It shows the outputs, A 1/2 HPO single stage pump will deliver 17 +/- GPM with no pressure and a 5' or less lift.

    The next graph is for the same pump with another impellor/stage added. It does 13 GPM but delivers a higher pressure. Not double the pressure or volume.

    If you want to know what is going on, use gauges.

    http://www.femyers.com/ResidentialProduct_my_ws_jt_HC_HCM.aspx
  • icesailor
    icesailor Member Posts: 7,265
    edited December 2014
    @ironman:

    "" Two pumps in series = twice the head, same gpm;
    Two pumps in parallel = twice the gpm, same head ( approximately stated). ""

    You've proved that with gauges? "Approximately" is the key word. It just needs to be defined.

    Meaning like Horseshoes and hand grenades?

    Look at Submersibles. The more stages, the less head delivery. The larger motors are to push a greater head/weight of water. Look at the discharge of a 1/2 HP 12 GPM pump and a 1/2 HP 20 GPM pump.

    http://www.femyers.com/ResidentialProduct_my_ws_4s_Predator_PLUS.aspx

    Nothing doubles.
  • Ironman
    Ironman Member Posts: 7,373
    @‌ Icesailor
    I figured that you'd like to challenge that. So yes, I did have gauges. And yes, it has also been told to me by an engineer a long time ago. And you can do an online search and get the same answer.

    You seem to be on a bent to challenge a lot of what I say. Why is that? I don't treat your statements that way. In fact, if you'll check, you'll see quite often that I've agreed with them.

    I believe that the name of this site is HeatingHelp. I don't see how it helps those seeking answers for the pros here to try and knit pick what each other say.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    RobG
  • icesailor
    icesailor Member Posts: 7,265
    I don't mean to challenge you or anyone here. I ask questions with questions.

    I was told, or someone asked the question about ganging up pumps. That's the way I understood the answer. The biggest difference in using booster pumps in hydronic heating systems over water well pumps is that with water well systems, the first pump always sees a constant pressure. All other pumps see an increase from the prior pump. But that each pump doesn't double the output from the prior pump.

    I completely understand Gennady's use of two pumps for his special application. I just don't think that the two pumps together give you twice the flow.

    If Joe M. or someone from Taco says that they do double the output, in any and all applications, I'd still like an explanation of how and why? It doesn't work with water pumps. The only way to pump more water at higher pressures is with bigger impellors and more Horsepower. Both run inside the performance curves. A large segment don't know how to read a chart or understand what it means.

    Sorry you feel offended. Its not my intent to upset or offend anyone.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    gennady said:

    Second pump accepts discharge pressure of the first pump as a return pressure. Pressure of the 2 pumps doubles, but gpm stays the same. This is the system with single entry valves on some really big cast iron radiators (40+ sections), 180' pipe run and 9 gpm requirement. Considering high CV of single entry valve, long shoot of the water in the radiator and 15% pressure reduction of flow check, this was my attempt to find solution. I did not want to go away from VFD, and did not have a budget for Magna. Pump is set up for constant pressure, not for constant speed.

    So how is the performance of the pumps in this scenario? I'm sure you played with the valves a bit to see how the pumps reacted to pressure changes?

    Harvey
  • BigRob
    BigRob Member Posts: 322
    gennady said:

    alphas in series

    Right on! Did you try setting the first pump to constant power and the second pump to constant pressure mode? How did it work?

    I'm also curious how these pumps play in parallel in constant pressure mode. Anybody try that.
  • gennady
    gennady Member Posts: 839
    edited December 2014
    Heating system is closed system. Well system is open system. How I see it, water in closed system acts as a firm body, because it is uncompressible liquid. Pumps just moving water like a wheel in merry go around and these alphas on constant pressure just determined to maintain predetermined pressure gain over inlet pressure. There cannot be different GPM on these pumps in series because it would create areas of compressed or uncompressed water, and this is impossible in uncompressible liquid.
    Also, these alphas in series will keep same GPM as one, only increase pressure gain, and this was my goal. Top radiators single entry valves did not have enough pressure drop to shoot water trough radiators, and all I needed is an extra 4-8' of head with same flow rate.
  • bob_46
    bob_46 Member Posts: 813
    Ice said "both run inside their performance curves"
    Pumps can't run inside their performance curves they always run ON their performance curves.
    You are entitled to your opinions Ice but not your own facts.
    Please read the attached pdf.

    http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/TEH-1109A.pdf

    bob
    bob
    Harvey Ramer
  • Ok, here's the deal...

    Constant speed pump curve example. 0 GPM flow 10 feet differential (boost) pressure, 2 GPM 8', 4 GPM 6', 6 GPM 4', 8 GPM 2', 10 GPM 0'.

    Pipe a second circ in series (min 6 to 8 pipe diameters between please), the heads double (0 GPM 20', 2 GPM 16' and so on. Basically one curve fits on the top of the other.

    Now lets draw the system curve on the series circ curve. If it's a high friction loss (steep) system curve the flow does increase - but not double (hence series is a possible solution for high friction loss system issues). If it's a low friction loss (flat) system curve the flow will change very little if at all. Hence a low friction loss system issue (old gravity systems) would use two circs in parallel.

    ECM "smart" circs in series. At the very least they have to be set the same. Better yet, constant pressure setting.
  • icesailor
    icesailor Member Posts: 7,265
    In PARALLEL, NOT in Series, and in series with 8 pipe diameters of separation between the two pumps. To allow the turbulence to get organized.

    I went to a Taco Eat & Greet somewhere and they showed us how you could replace a Taco 1600 Circulator with to smaller, properly sized wet rotor pumps. In PARALLEL. I never saw any one do it because I'm sure that few knew you could do it, and they'd prefer to sell whatever was needed to replace the 1600.

    Water well systems are "Closed" systems until you open a faucet. While the faucets are closed, all the same pumping mechanics are still in play as you find in any heating system. They used to make positive displacement water pumps. The old farmers used them with Make & Break gasoline engines. Pumps like 1909 Myers piston pumps pumped 400 gallons per hour, No matter what the lift or the pressure. 400 GPH. Centrifugal pumps need "Pump Curves" to tell you what the performance is based on suction and discharge pressures. Because of the "Squish Factor". Centrifigal pumps have the squish factor because of varying inlet and outlet pressures.

    If Taco et al want to do a really fine thing, start offering and promoting flanges with 1/8" NPT test ports like they did for 112 circulators where you can put Presstaps in and connect pressure differential gauges. Like certified system balancers do to bring the ME designers plans to fruition.

    I don't have any problem with what goes on. But the more of this high tech equipment shows up, the more the lost get farther into the wilderness. Some of you here are working for manufacturers or distributors. What's the first thing you do when you go to a trouble job? Check to see if the arrow on the circulator is pointing in the right direction. I thought that P/S piping was to allow systems with different flow characteristics to work together. Then, boiler manufacturers had to start putting primary circulators inside boilers because the boiler pumps were being used to pump the whole system. No one reads the instructions or understands them.



  • icesailor
    icesailor Member Posts: 7,265
    edited December 2014
    bob said:

    Ice said "both run inside their performance curves"
    Pumps can't run inside their performance curves they always run ON their performance curves.
    You are entitled to your opinions Ice but not your own facts.
    Please read the attached pdf.

    http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/TEH-1109A.pdf

    bob

    You know what I meant. "On" or "Inside", it is along the curve. If you put two pumps together, unless there is a published performance curve for the two pumps together, they are probably pumping INSIDE the curve.

    And the post I was referring was about two pumps connected directly In series with no spacing between pumps. The article and example you posted for me is about parallel piping two circulators together. I never said anything about that. And the performance curves are the same for both pumps. The head doesn't go up, just the GPM. Which is what I said all along.

    Two pumps in series, increase the head pressure but can drop the flow.

    Two pumps in parallel will increase the flow and should have no effect on the head pressure.

    If you take one 1909 Myers piston pump, it pumps 400 GPH, no matter what the pressure or the suction lift. Two 1909's in parallel will pump 800 GPH. In Series, the GPH will remain the same. Same with the head because the ability of the motor to overcome the resistance of the pump(s) is the limiting factor.

    Centrifugal pumps are different. Your B&G example uses centrifugal pumps.

    When you go fishing, and you aren't catching any fish, you try a different lure in hopes.

    Sometimes, it seems like some are fishing.

    And I don't mean that to you Bob. I mean it to some who come here all confused about pumping and boilers running.

    My brain thinks like Steamhead and the other Steamer's here. They look at a troubled system and immediately, their mind knows where the steam will go and not want to go. Same with water.

    There's a post here now about someone with a variable speed pump that won't pump into a loop on a lower pressure, but will if he increases the pump pressure. That's increasing the head pressure. The head pressures won't increase much in the working zone, but it needs to increase in the non-working zone. And when he increases the pressure, the zone will work. Right?

    I installed a Wilo ECM circulator on my 5 zoned, zone valve system. The pump was 3X the cost of the 007 I replaced it with. Did I save any money on electricity with the ECM motor? Not if I left the 5-8' tube fluorescent lights (150 watts each) on in the cellar if I had to go to the lumber yard to get something. for a couple of hours.

    But the motor did slow down.

    I liked the concept. I understood it. No one else did, but I did. As soon as I saw it at the Wilo Eat & Greet at the supply house. No one around understood the concept but me.

    I'm German. I like Technology for technology's sake. Thete's that Scot's on me that says "Easy lad, careful what you spend it on".

    Then, I think about battle tanks in WW ll. Germany made the most advanced tanks in the world at the time. But they were expensive and to build and complicated to repair. Someone in the USA mada a command decision to build cheap Sherman Tanks. We could build 3 or 4 to every one that Germany built. Some were so big that they had to build special bridges to cross rivers. We gave the Sherman's to the British. German tanks were almost impervious to fire from a Sherman. German tanks would blow up a Sherman as fast as they could shoot at them. We just had more of them. The Germans referred to Sherman's as "Tommy Cookers" for their ability to blow up and catch on fire. But we built lots of the Sherman's. Lots more than Germany could ever build. Just because something is bigger, better and cost more, doesn't mean it is better.

    Then, there's the Russian T-37 tank. Cheap to build, costly to go against. It could cost you your life.



  • Paul48
    Paul48 Member Posts: 4,469
    Always pump away from your T-37 tank.
    RobG
  • hot_rod
    hot_rod Member Posts: 22,107
    Our next idronics, due mid January, will talk about pumping. Non generic info with circs of all colors included :)

    I've been told the head doesn't exactly double as there is some flow restriction in the nipple between, I agree there should be some length between them, but close enough for this argument.

    I has an Alpha in series with a 15-58 on my drainback solar for awhile. Both circa fired to fill, then the 15-58 dropped off and the Alpha (fixed speed) pumped the 5 collector array on about 20W!
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • icesailor
    icesailor Member Posts: 7,265
    @hot rod:

    The two Alpha's shown in the photo are two circulators connected flange to flange, No space between.

    As far as your Idronics, when I was at a Eat & Greet where I first saw the Wilo ECM circulator and bought one, I got the complete selection of the Califfi Idronics and read them all, very carefully. I wish I still had them.
  • hot_rod
    hot_rod Member Posts: 22,107
    Ice, send me your mailing address
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    jonny88
  • icesailor
    icesailor Member Posts: 7,265
    hot rod said:

    Ice, send me your mailing address

    I did. Hopefully.

  • gennady
    gennady Member Posts: 839
    Thanks everyone for input.
  • Ironman
    Ironman Member Posts: 7,373
    gennady said:

    Thanks everyone for input.

    Did putting the nipple between them seem to make any appreciable difference?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • gennady
    gennady Member Posts: 839
    Not really, i did not need to double the head, just maybe 25-50% increase, but it was right thing to do.
  • Ironman
    Ironman Member Posts: 7,373
    gennady said:

    Not really, i did not need to double the head, just maybe 25-50% increase, but it was right thing to do.

    That's one thing that I appreciate about you: you're gonna do it right, even if it's at your own expense.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • icesailor
    icesailor Member Posts: 7,265
    If there's a boiler drain on the left side (like the right side), I'd be interested what the differential pressures are. And what happens when you dial the numbers up and down with the two circulators. Could be a real teachable moment.
  • BigRob
    BigRob Member Posts: 322
    gennady said:

    Thanks everyone for input.

    What happens when you put the second pump in line in constant pressure mode? Does the speed hunt, or settle in and stabilize?
  • gennady
    gennady Member Posts: 839
    I was not there, just sent a crew to do it. The drain cock to the right is a bleeder, so we will not let air into the system when work is done on this part of the system, But considering that this is fully trv job with outdoor reset, it is probably very dynamic in therms of flow and stable in pressure differential. if i would go down in pressure setting, then top radiators will stop heating again, but pressure will be stable, unless GPM increased and then pressure will slip along the right part of slope of the corrected curve.
  • gennady
    gennady Member Posts: 839
    edited December 2014
    it is in constant pressure now. I do not use auto adapt or constant speed.
  • BigRob
    BigRob Member Posts: 322
    gennady said:

    it is in constant pressure now. I do not use auto adapt or constant speed.

    Ah, I see that now. Questions:

    1. When both pumps are set to constant pressure, do the speeds tend to track one another?
    2. What happens if each pump is set to a different constant pressure setting?
    3. What happens when the 1st pump is in a constant power mode and the pump after it is in constant pressure mode?

    Inquiring minds want to know.
  • icesailor
    icesailor Member Posts: 7,265
    That's sort of where my mind was. I never said or meant to infer that it was wrong. I was curious of the mechanics.
  • gennady
    gennady Member Posts: 839
    BigRob said:

    gennady said:

    it is in constant pressure now. I do not use auto adapt or constant speed.

    Ah, I see that now. Questions:

    1. When both pumps are set to constant pressure, do the speeds tend to track one another?
    2. What happens if each pump is set to a different constant pressure setting?
    3. What happens when the 1st pump is in a constant power mode and the pump after it is in constant pressure mode?

    Inquiring minds want to know.
    1. When both pumps are set to constant pressure, do the speeds tend to track one another?
    2. What happens if each pump is set to a different constant pressure setting?
    __will have to check this

    3. What happens when the 1st pump is in a constant power mode and the pump after it is in constant pressure mode?
    __ will not work in this set up, it will lead to trvs knocking in mild weather due to excessive pressure i think.
  • Couple of points:

    Proper pump (circ) installation is to have at least 3 pipe diameters of straight pipe on the inlet side to create a laminar flow into the pump (includes not bolting Y strainers directly to the circ inlet). Same holds true if installing two in series - just good installation practice (the water coming off a circ is very turbulent). Agreed on small circs you can "sort of" get away with it but it is not the best thing to do and POTENTIALLY can shorten the life on the downstream circ. This is a mandatory requirement with larger pumps for sure (min 3 pipe diameters or inlet straightening vanes). Actually applies to the location of air scoops and pressure gauge locations as well.

    Second, and one I missed in an earlier post, take care to insure both ECM circs are powered at the same time. If the downstream circ is off and the upstream circ on, fluid forced through the downstream circ can cause the it's impeller to spin - turning it into a generator potentially damaging the electronics and/or causing a nasty surprise to a service person that might get electrocuted. This only is an issue with ECM wet rotor pumps.
    BigRob