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Circulators that you can set GPM

tom3holertom3holer Member Posts: 45

I am having a new Alpine 80 installed today to replace the way oversized boiler that was installed about a year ago. Having been doing a lot of reading and research and feel somewhat up to speed. One of the things I would like to do is set up the P/S flows properly as I understand the way they should be. My plumber came over yesterday with the new boiler. I talked to him about primary and zone flows and he said I just used whatever pump comes with the boiler and uses 007's for each zone. From what I have read you want D/T's on the primary of 30-35* and the zones should be 20* for best chance of operating in the condensing mode more often.The Alpine manual does have a chart showing required flow for a given D/T. I realize that this is at max output and will be less as the boiler mods down.  I have one Taco Bumble Bee that I will use in one of the 3 zones I have utilizing D/T to set flows. The primary however I want to set a fixed GPM and know that is what I have. Are there any pumps that you can set the actual GPM? The Bumble Bee does not seem to be able to do this.




  • GordanGordan Member Posts: 891
    edited April 2013
    There's no advantage to this on the system side

    Just get yourself a flow meter if you want to know what the flow is. A Grundfos Alpha will indicate how much it is flowing, rounded to the closest whole gpm. Another benefit is that it will speed itself up or down as needed, based on zone valves opening and closing, so your zone flow should remain relatively constant.

    EDIT: Never mind, I misunderstood - you want fixed gpm on the boiler loop, not the system. Well... ANY circulator will do a fixed gpm. If you want to dial it in exactly, then something like a B&G Ecocirc e3 or the Wilo Stratos Eco will allow you to turn up the pressure differential setting and a flow meter is still the best way to indicate flow.
  • ChrisChris Member Posts: 3,056
    Sure It Does

    It will operate on it's curve based on the head of the primary side. Just need to get your total primary side head loss. You have the head loss of the HX, On the 30 Rise you need to move 4.9gpm - HX Head loss is 6.4' plus maybe a foot for piping. Puts you right at setting 3 on the bee.

    If your looking for the 35 Rise and have to move 4.2gpm. HX Head loss is 4.8' plus again about another ft for piping and that puts you right in the wheel house for a Taco 006.

    Just have to make sure your head loss calculations are correct.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • ZmanZman Member Posts: 3,517
    Zone circ

    If you want a fixed gpm on the boiler side just look at the charts and buy the correct circ. There is very little guesswork in that.

    Why in the world does he want zone circs. Zone valves and your bumble bee will use far less energy.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • JeffGuyJeffGuy Member Posts: 70

    So you're taking out a two year old Alpine 150 to put in a brand new Alpine 80? Is someone covering the cost of the replacement boiler? I have a lot of trouble believing this is in any way necessary or that it will be cost effective?
  • EastmanEastman Member Posts: 783

    DId you take out some of those pumps?  --I recall seeing 5 in the photos.  Do you have three thermostats?
  • ChrisChris Member Posts: 3,056

    He has an Alpine 150 with a heat loss of 60K. Boiler short cycles and will take forever to get into condensing mode due to the 13gpm being moved by the boiler circ. The system cannot take it away so it keeps his return temps elevated.

    I hate seeing all those zone pumps. Without circuit setters those zones are being over pumped which doesn't help allow the emitter to pull the btu/hr it needs. I would be zoning with Taco Zone Sentry's and a Bumble Bee (preferred) or a Alpha for a system pump.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • tom3holertom3holer Member Posts: 45
    edited April 2013

    Thank you all again for the advice and guidence.

    Well first the 150 is less than a year old and the plumber is buying the replacement boiler. We made a deal that he could have the old boiler if he would do some additional plumbing for me. Not too bad a deal as there was a $1500 rebate when I bought th 150 but the Alpine is derated to 92% now fo some reason, so the new ones do not qualify. Some of the redo was correcting his not "Pumping Away" setup. Zone pumps are in the return lines and I have had air in the upstairs zone two or three times now.

    Yes Eastman, there are 5 circs in the photo. One is for the DHW and the others are for the 4 zones. I tied two of the 3 downstairs zone circulators to one thermostat and had very even temps in those rooms during the colder days. It was an attempt to unload the boiler more. Part of what my plumber is doing is to replumb those 2 zones as one. That has created differences on how to do it which leads to another question I have if I may:

    Right now there is one line, a 28' run of 1" that splits and receives water from the  2 zones running each side of the house. One loop has 51' of bb and 41' of 3/4. The other has 42' of bb and 30' of 3/4. He wants to tie the two loops together where they split and eliminate the 28' 1" then feed it as a single long loop. I don't like the idea because if I shoot for a 20* D/T the last portion of the loop is going to be getting much cooler water and resulting, me thinks, in uneven heating. I want to keep it as is except feed the water to the 28' 1" and tie the two returns together making it  2 parallel loops abit with different head values. Put a circuit setter or something in the shorter loop to equalize the flow and it should work, I think. He sees my reasoning but not sure he agrees with it. What do those of you with far more experience than I think? 

    The wife is off to Paris for a month to immerse herself in the language by taking an intensive language class. This leaves me with the dog and my copy of Modern Hydronic Heating which hopefully I will get through by the time she comes home....OK on to chapter 7.

  • ChrisChris Member Posts: 3,056

    The Alpine was re certified to 95% and Burnham will send a new label. .
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
  • knotgrumpyknotgrumpy Member Posts: 207
    B&G Ecocirc 19-14 Vario

    Just turn the dial from 1 to 7.  These are very nice ECM circulators and B&G has OUTSTANDING customer service!

    I've attached the curve charts for both the Auto and Vario models.
  • EastmanEastman Member Posts: 783
    Generally speaking...

    I would not put it in series.  Is there a reason you have to reverse the flow?  Perhaps the original installer had high hopes that the high temp side would balance out an undersized fintube unit or window.
  • Steve Thompson (Taco)Steve Thompson (Taco) Member Posts: 133
    Set GPM

    Guys, this is a lot tougher than it appears...

    First, an ECM circs "calculates" or estimates flow - and none of us are that accurate (hate to say it but that's the way it is).  Second, it's a function of the where the system curve meets the circ curve.  If the system curves does not move then you could set constant flow with a 3 speed circ.  But if the system curve moves(flow and/or friction loss changes) delta T, delta P or three speed can not guarantee constant flow.

    A true constant flow circ would have to have code written it the software that would have it react to flow changes like it does with temperature or pressure control (like a constant pressure setting).

    Again, stupid question - other than chillers, when would you want constant flow?
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