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one circulator for 2 zones and indirect water heater?

ron
ron Member Posts: 146
edited August 2015 in THE MAIN WALL
going to be getting a wgo-3 oil boiler, and i have a new weil 42 gal. indirect water heater and a taco viridian VT2218 circulator. Pondering if it's ok to use just the one circulator the VT2218 in a hydronic system that has 2 zones for house heat and an indirect water heater?
The plumbing would be: boiler output to --- taco 4900 air separator & expansion tank to --- VT2218 circulator to --- tees branching out to zone1, zone2, and hot water heater. I currently have 2 taco zone valves one on each return side of zone 1 & 2. If I get a 3rd zone valve and have it put it on the hot water heater loop... with the burner controller set up for hot water priority? {is that what it's called?} would that work?
what are the pro's and con's of having one circulator, versus a 2nd one that's dedicated to the hot water heater loop?
fwiw i also plan on using taco freedom flanges with the circulators,
and i've done heat load on house it's 2 story and not much more than 30k btu each floor loss at 0°F outside 70° inside.
thanks.

Comments

  • JStar
    JStar Member Posts: 2,752
    It all depends on the fow requirements of the most restrictive part of the system, and the CV/flow rating of a zone valve that would serve the DHW.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    I prefer a dedicated circ for the indirect. On priority over the heat zones.
    Steve MinnichZman
  • ron
    ron Member Posts: 146
    weil recommends 8gpm for their hot water heater and it has 3.3 feet of head on boiler side. plumbing will be 1" copper. given the hot water heater priority i have a hard time seeing why i'd want to bother with a 2nd circulator dedicated to the hot water heater loop. The VT2218 would meet 8gpm no problem up to 11-12 feet of head.
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    Not a fan of zone valves on indirects. There's some delay on response, they are more prone to failure than a pump. You asked.
  • ron
    ron Member Posts: 146
    thanks, that's why i'm asking.
  • hot_rod
    hot_rod Member Posts: 14,785
    edited August 2015
    With an 8 gpm flow requirement you are well within reach of most 1" off the shelf zone valves.

    Here is a very reliable ZV, get a 1" with a 7.5 Cv and you could get away with a single circ system, easily.

    Very small pressure drop at 8 gpm.

    Upsize to a 3 zone relay board and the wiring becomes simple and DHW priority is easily accomplished.

    If you had a large flow requirement, or excessive pressure drop indirect, a dedicated circ might be a better choice.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    Robert O'Brien
  • ron
    ron Member Posts: 146
    edited August 2015
    so i'm thinking of a 1" taco Z100C2-1 zone sentry valve on the hot water heater loop, the Cv is 8.9.

    what is the time delay for this kind of zone valve to open?
    or when it's connected to a hot water heater priority on the burner is that automatically handled?
  • Rich_49
    Rich_49 Member Posts: 2,565
    5 seconds after charge time is what is published
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    Zone Sentry is a great choice if you're going zvs. Calleffi as well.
  • Rich_49
    Rich_49 Member Posts: 2,565
    I agree with Bob for the most part . In your particular instance considering what type boiler and all else . One pump would be quite good here with the DHW as priority . The zone valve ha sthe proper Cv listed for your needs and the VT2218 is quite capable , right around the middle of the curve too .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
    Bob Bona_4
  • j a_2
    j a_2 Member Posts: 1,796
    If you do use zone valves after your math...I like the IPS as opposed to sweat zone valves...jmo
  • Dave H_2
    Dave H_2 Member Posts: 439
    Ron,

    As most everyone said above, I would use a separate circ for the DHW. Now, There are plenty of jobsites where one circ and zones valves for two heat zones and one DHW zone. However, your choice of the VT 2218 is a different animal.
    The VT will speed up and down for the heating zones based upon the Delta T, however when there is a call from the DHW tank, the need for a variable speed circ is moot. Fixed speed is desired at that point and the VT cannot change modes automatically.

    Dave H.
    Dave H
    Bob Bona_4
  • Bob Bona_4
    Bob Bona_4 Member Posts: 2,083
    Dave, I could only select one of the choices, but the others would be "insightful", "like", and "agree" :)

    Good to see you stopping by!
  • hot_rod
    hot_rod Member Posts: 14,785
    With zone valves, a delta P circ might be a better choice. Any or all zones would get the flow they need.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    j a_2Robert O'Brien
  • ron
    ron Member Posts: 146
    Dave H said:

    Ron,

    The VT will speed up and down for the heating zones based upon the Delta T, however when there is a call from the DHW tank, the need for a variable speed circ is moot. Fixed speed is desired at that point and the VT cannot change modes automatically.

    Dave H.

    The vt2218 comes with 2 temperature sensors. if i set the circulator to temperature sensing mode 20° delta-T, and it's wired for hot water priority, and one temperature sensor is on the return of my upstairs zone heat after the 2 zones tee back into 1" and the other temp sensor would be on the 1" return pipe from the hot water heater but before that 1" tee's into the piping from the upstairs zones.
    I'm having trouble understanding what would the problem be on the hot water heater loop? would the circulator not operate fine according the pump curve, the hot water heater wants 8gpm flow and then since the circulator would modulate to maintain a 20° temperature difference isn't that what is wanted regardless of whether the heat load is my baseboard heaters upstairs or the hot water heater?


  • Great thought provoking question Ron. I'm thinking there are a couple of things to consider here.

    Our VT 2218 works on both delta T and setpoint. Let's think about delta T setting for now (although you can increase the efficiency of the boiler by helping it condense, keeping the return water temp as low as possible while maintaining comfort) - AKA setpoint mode with sensor on the return line.

    If you have an outdoor reset it might be an idea to leave as it for a 20deg delta T on the heating loops. But, here's the challenge...

    The input temperature demand on the indirect HX is pretty much consistent regardless of the outdoor air temp. That being said, again assuming you have outdoor reset, it is very probable you will have different supply temp requirements of the heating system and DHW system. So, thinking of the two different applications (space heating and DHW) the temps are different, the loads are different and the delta T's would probably be different as well.

    As much as I don't want to suggest you need two separate circs I'm really not sure how this would work using only one. Even if the indirect had the same design delta T as the heating system (for maximum system efficiency) you would be mixing different return water temps affecting supply temps, boiler firing rate and so on.

    How about this - use the VT 2218 on the heating loops in delta T mode and a separate VT 2218 dedicated on pumping water through the indirect HX? Set up the DHW dedicated VT on setpoint, maintaining the DHW supply temp to the fixtures or the temp in the DHW tank itself?

    Drop me an E Mail @ [email protected] - I'll send out a VT 2218 for you to test if you are interested (I know I am).
    Rich_49
  • ron
    ron Member Posts: 146



    - As much as I don't want to suggest you need two separate circs I'm really not sure how this would work using only one. Even if the indirect had the same design delta T as the heating system (for maximum system efficiency) you would be mixing different return water temps affecting supply temps, boiler firing rate and so on.

    i will be getting a new wgo-3 oil fired boiler and i don't think i'll be using outdoor reset with it. going to keep it warm start keeping boiler > 160°F (I think that's the temperature they kick on at) for longevity and cleanliness. so for the baseboard heating zones they would be running the typical return temps of around 160°F and getting supply temp from boiler of 180°F.
    now i was planning on doing the hot water priority thing so when the hot water heater calls then if the baseboard heating zones were running those zone valves would close.
    Now the only loop running would be for the hot water heater.
    From the boiler's point of view, it doesn't know any better of what circulators there are. For arguments sake if there was 1 circulator for everything then with hot water heater priority those running the baseboard heat zones would stop (stopping that 180°F supply temp and 160°F return temp process) and then the circ for the hot water heater would kick on. Now that 1 circulator whatever make/model is running the hot water heater loop.... whether it's a dedicated circulator or it's 1 taco VT2218 delta-T circulator I don't see the overall process changing because the baseboard zones get turned off. How would it be any different from boiler's perspective, I see it as a simple on/off switch for the flow of water either way?
    so if it was just the one delta-T circulator doing everything then i understand it seeing a dramatic change in flow temperatures when the hot water heater loop first turns on, but it would be a one time change and would expect the circulator to adjust flow properly and quickly get back to a delta-T of 20° on the hot water heater loop flowing the recommended 8gpm and higher... so i think it would make the boiler happy because the boiler would more often see a 180° supply and a 160° return versus having a non-delta-T circulator on the hot water loop.
    hope this brain dump to text made sense, someone let me know if and where i'm going wrong. thanks.

    Rich_49
  • hot_rod
    hot_rod Member Posts: 14,785
    Then why not run a delta T of 12, or 10. Seems to me if fast, efficient DHW recovery is a goal, a properly sized circ, running full speed would be best, why limit delta T if the tank can accept all the hp the boiler can offer? Assuming proper pipe sizing to handle the gpm of course.

    It seems a delta T function for DHW is driving with the petal to the floor (boiler running at capacity) and the circ pump putting the brakes partially on. While the boiler may cycle as the tank nears set point, is that a trade off to limiting moving the energy between the boiler and tank.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Rich_49
    Rich_49 Member Posts: 2,565
    Manufacturer states 8 gpm @ 3.3 feet using 180* water for rated performance .
    I just now spoke with Steve from WM Tech support and their ratings are based on an incoming temp of 50* and a target temp of 140* . Boiler side ratings at 180 , 190 , 200 * are based on return temps to the boiler being , 20* less than supply .

    But Ron may choose to follow Bob's advice and flow twice that and deliver half the BTUs back to the boiler and not leave them where they were supposed to be left .

    Increasing the Delta 5* between the incoming domestic and the circulating boiler fluid does not help all that much with production or recovery .

    Delta T is evidence of the BTUs that were delivered .

    8 gpm = 80,000 / 20* x 500
    16 gpm= 80,000 / 10* x 500
    Did we gain anything by flowing 2xs fluid ? Will the boiler still cycle ?

    Your original question was could you utilize one pump with a Delta T logic and have it work as intended on this system .The answer is Yes , you can , all things considered . make sure that DHW ZV is 1"

    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • hot_rod
    hot_rod Member Posts: 14,785
    If you are under the false impression that btus can't jump off a fast moving train, try shutting the pump off and report back. Plenty of time to jump from a stopped train
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 14,785
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Rich_49
    Rich_49 Member Posts: 2,565
    edited August 2015
    I am not disillusioned in the slightest Bob . They can certainly jump off the train but the question is , what condition will the remains be in ?

    Btus that break the laws and jump off those trains suffer the death penalty and leave very little positive impact on the world where they once resided . BTUs can jump from the train at all kinds of speeds , what they are capable of is an entirely different discussion .

    Explain how a 10 foot piece of SF F/L 30 @ 140* AWT delivers 3200 BTUh at a flow of 1 gpm but only manages a meager increase to 3400 BTUh by increasing flow to 4 gpm . The 6% increase you gain will almost certainly be lost right up the stack while the boiler is off on limit .
    Maybe BTUs are not as stupid as you believe . Once again I take one from Planck , " frictional pressure Never does positive work ."
    Maybe you could show me a study , white paper , or publication that supports your theory that jamming something through another thing at higher than recommended flow rates is beneficial . Maybe you could also tell our poster how much your strategy would increase his head , power consumption , and how fast it will negatively impact his piping . Then maybe you could contact Weil McLain and request they publish your recommendations on their site for distribution to the customer and the already stupid contractors installing this stuff . You've got time for that right ?

    Ron , there's the math , hope all works out well and hope what I have offered makes sense .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • Rich_49
    Rich_49 Member Posts: 2,565
    0013 VDT
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • hot_rod
    hot_rod Member Posts: 14,785
    The 20 delta T is an arbitrary, made up number that has little if any value in hydronic design. The rest of the hydronic world laughs we they hear that number being used because it "makes the math simple"

    If we sell an indirect tank to a customer usually we promote the benefits of quick, and efficient DHW, and hopefully long lasting performance. To promise that to a customer them impose a bogus 20 delta T that limits performance and promised value is a sham, in my opinion.

    Example, design day, house maintains 70f, 0 outdoor, all zones running, boiler running full output, non stop. An ideally sized and installed system.

    My wife takes a tub, dishwasher is running, tank is drained of hot water replaced with 50 degree water.

    System goes into DHW priority, full boiler output is available to DHW, heating zones locked off due to priority call.

    If I can flow all the boiler energy into a tank maintain a high coil AWT with a 10 delta T, my 50 degree water is against a coil or HX with a 180 AWT. Why would I ever want to limit that wide delta T, slow the recovery, and keep the heat zones off for an hour or more? What value do we have in slowing down the performance of an expensive DHW device, just to appease an arbitrary 20 delta T number.

    My preferance would to be recover that tank in 15, 20 minutes, whatever the boiler could muster. Many Indirects can accept 200,000 btu/ hr. far beyond the typical residential boiler size.

    In some cases with a restrictive HX indirect which you shouldn't be using anyway, maybe it cost a few more pennies in electrical cost, no big deal to provided promised DHW and performance.

    Until Donald a Trump changes the laws of thermodynamics, I'm sticking with this proven concept.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    zavnet
  • Rich_49
    Rich_49 Member Posts: 2,565
    Wrong Bob .
    Your 50 * water is against an AWT of 175* assuming equal length supply and return piping . Weil McLains specs call for the water to be against a 170* AWT .
    What really strikes me is your readiness to use higher temps and higher flow rates when the whole rest of the world is trying to do the opposite .
    http://www.brazetek.com/docs/pdf/brazed-plate-heat-exchanger-quick-sizing.pdf

    http://www.taco-hvac.com/uploads/FileLibrary/200-2.3.pdf

    http://www.weil-mclain.com/en/assets/pdf/brazed_plate_heat_exchanger_wmbp_manual.pdf

    Funny that I cannot seem to find one manufacturer whom agrees with you . Granted they may be wrong , but not by that much . Delta T is a result , not something magic or even mysterious as you have people believe .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    732-751-1560
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • That is exactly why I suggested using the VT in setpoint mode for the indirect. A low delta T on an indirect obviously doesn't make a lot of sense.
  • hot_rod
    hot_rod Member Posts: 14,785
    The 180 I used was a random number, many boilers actually run to 190f on indirect call, mine does. My point is the wider that delta and the higher the HX surface average temperature, the greater the rate of HX

    We run into this same misunderstanding with solar thermal all the time. Some think the "linger" time of the fluid in the collector adds to energy harvest. While the opposite is actually the point, scrub the btu as fast as the sun provides them, get them into the tank before the ambient grabs them while they "linger"

    Agreed within a reasonable pump size, whoever decides that
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    edited August 2015
    This is the delta T on a new install with a 3 speed fixed speed Taco...Pretty close to 20...
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    Its a 0015 - MSF3 -IFC 3 speed. I will confirm setting tomorrow. We had a pressure issue and were playing with the setting to see if that was the cause. We had a bad check stop for the Caleffi boiler trim system.
    We have 1-1/4" from the boiler to the SEP 4 with a 1" supply and return to the indirect inside the primary loop.
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    edited August 2015
    I will check...just noticed something interesting. For the boiler we used (HTP EFT-155) the delta T in temperature rise goes up with the slower GPM. So if we had a VDT as the flow slowed when reaching set point in the indirect the water would heat quicker going through the boiler HX. I need to chew on this...Need to be the water...
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
  • Hatterasguy, really appreciate and respect your comment. I am definitely learning (and a believer in the KISS system BTW). Funny how the "learning" continues after 40 years in the business - that's one of many things that make it great!

    But, let's assume the target tank temp on the DHW side is say 160 deg F. Use a setpoint circ set at 160, mounting the sensor at the DHW side to see the target DHW tank temp.

    System satisfied, pump and boiler off. Call for hot water, tank temp drops, pump speeds up (speed dependent on differential between setpoint target temp and reality - faster with more differential). Boiler sees a load, fires. Tank temp continues to drop as DHW drawn off. Boiler and circ continue to increase output until tank temp starts to catch up with setpoint.

    I see two issues with this (correct me if I'm wrong). Slower than desired reaction and what do you actually gain from a setpoint circ in this application? Wallies please enlighten me (this will set the direction of our DHW recirc product development so it is very important for me to get this right).
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    The target sensor would have to be in the well. The issue I see is on a DHW call the supply water will be at or above the 160 target. It could be 180 to 190. The return water would be at the target temp or close to it... see my picture above.
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
  • hot_rod
    hot_rod Member Posts: 14,785

    Hatterasguy, really appreciate and respect your comment. I am definitely learning (and a believer in the KISS system BTW). Funny how the "learning" continues after 40 years in the business - that's one of many things that make it great!

    But, let's assume the target tank temp on the DHW side is say 160 deg F. Use a setpoint circ set at 160, mounting the sensor at the DHW side to see the target DHW tank temp.

    System satisfied, pump and boiler off. Call for hot water, tank temp drops, pump speeds up (speed dependent on differential between setpoint target temp and reality - faster with more differential). Boiler sees a load, fires. Tank temp continues to drop as DHW drawn off. Boiler and circ continue to increase output until tank temp starts to catch up with setpoint.

    I see two issues with this (correct me if I'm wrong). Slower than desired reaction and what do you actually gain from a setpoint circ in this application? Wallies please enlighten me (this will set the direction of our DHW recirc product development so it is very important for me to get this right).

    For DHW recirc you are trying to accomplish a completely different task from indirect DHW recovery. In my mind the goal is to recover the DHW quickly, transfer the most amount of energy in the least amount of time. I hope everyone agrees that the hotter the coils or whatever the HX device is, the faster that recovery will happen.

    By now it should be clear that higher flow rates equates higher HX surface temperature. That is not the question Rich posed to WM, so the answer was not in those WM numbers, by the way. Hatt already commented on that.

    With DHW Reci the ONLY job the recirc pump needs to be concerned with is overcoming the heat loss of the piping circuit, and having enough "fizz" to overcome the pressure drop of that loop. From the WH, to the most distant fixture and back.


    . The biggest factor becomes how much temperature drop is in that loop. If it is uninsulated copper in an unconditioned space, that flow requirement will need to adjust to account for that.
    That would be more off radiant heating loop than a recirc loop.

    Insulation would be a better solution. The flow needed to keep that loop sufficiently warm should not vary all that much unless the temperature of the space where the piping run has wide temperature swings. If so a variable speed recirc could have some value.

    Again with KISS in mind, shut the recirc pump off when the loop reaches temperature works well enough. No need to have any flow in the loop once it's sufficiently warm and can stay warm.

    Certainly an ECM recirc would add some energy savings value.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356

    I see two issues with this (correct me if I'm wrong). Slower than desired reaction and what do you actually gain from a setpoint circ in this application? Wallies please enlighten me (this will set the direction of our DHW recirc product development so it is very important for me to get this right).

    Setpoint and ΔT both have applications in DHW recirc. Give me a stainless or composite volute version of the VT2218 with the same electronics and I'm off to the races for light commercial recirc.

    How about a half-sized version (VT1109)?

    Rich_49
  • hot_rod
    hot_rod Member Posts: 14,785

    Hatterasguy, really appreciate and respect your comment. I am definitely learning (and a believer in the KISS system BTW). Funny how the "learning" continues after 40 years in the business - that's one of many things that make it great!

    But, let's assume the target tank temp on the DHW side is say 160 deg F. Use a setpoint circ set at 160, mounting the sensor at the DHW side to see the target DHW tank temp.

    System satisfied, pump and boiler off. Call for hot water, tank temp drops, pump speeds up (speed dependent on differential between setpoint target temp and reality - faster with more differential). Boiler sees a load, fires. Tank temp continues to drop as DHW drawn off. Boiler and circ continue to increase output until tank temp starts to catch up with setpoint.

    I see two issues with this (correct me if I'm wrong). Slower than desired reaction and what do you actually gain from a setpoint circ in this application? Wallies please enlighten me (this will set the direction of our DHW recirc product development so it is very important for me to get this right).

    @Rich and I had a rather intense discussion concerning this issue tonight and we have reached a conclusion.

    The conclusion is quite different than my original presumptions regarding a smaller DT offering better DHW performance.

    Here's why:

    If, by some miracle, the 007 can flow at sufficient GPM to obtain a DT of 15, we would conclude that the AWT would be higher and the performance of the indirect would be better.

    The problem with this conclusion is that it is technically correct but practically it's insignificant.

    Here's why:

    The AVERAGE water temperature of the DHW in the tank at the bottom of the tank is estimated to be about 90°F when there is a hot water demand. 50°F water is flowing into a tank that was previously maintained at 130°F. The average SWT from the boiler is stated to be 170°F. Therefore, an 80DT between the two.

    If we reduce the DT between the supply and the return from 20°F to 15°F,, we increase the AWT by 2.5°F.

    2.5/80= 3% performance improvement.

    NEGLIGIBLE


    Now let's say the demand ends and the indirect temperature has climbed back up to an average of 120F on it's way back to 130°F. We still have an AWT from the boiler of 170°F. A 50DT between the two.

    We increase the flow rate to get a DT of 15 between the supply and return to the boiler. AWT goes up by 2.5°F.

    2.5/50= 5% performance improvement

    NEGLIGIBLE


    Now let's say we put a hydraulic mining pump on there and get a flow rate of 16 GPM and reduce the DT from 20 down to 10. The AWT goes up by 5°F. We'll use an average tank temperature of 90°F with the cold water flowing. Therefore the DT between the boiler SWT (175F) and the tank temp (90F) is: 85°F.

    5.0/85= 6% performance improvement


    NEGLIGIBLE


    And, we suffer all the detrimental effects of a 16 GPM flow rate in 1" piping, including the cost to run the big pump and the piping erosion.



    So, at the end of the day, attempting to get better performance from an indirect by reducing the DT between boiler supply and the boiler return to something less than 20 is an exercise in futility and the plan that the OP has for using the 2218 at a 20DT for both domestic heating and DHW will work perfectly well.


    Regarding the setpoint circ...............it's an additional expense that doesn't offer any gain for the OP. Its reaction time is slower and it's speed will reduce significantly as the tank temperature climbs up toward the setpoint. It might take a long time for the tank to climb the final 10F. The boiler will likely hit HL during this period (because the flow rate is significantly reduced as the temperature of the tank closes in on setpoint).

    The only way to fully know what the setpoint circ will do is to know its algorithm. What's its flow rate when the pump is right at setpoint? What's its flow rate when the pump is 5 degrees below setpoint? What's its flow rate when the pump is 10 degrees below setpoint............etc? That's all proprietary to Taco so it's a bit difficult to analyze the VS pump without it.

    I concede in this example the juice may not be worth the squeeze for the additional performance.

    If that Weil indirect is a tank in tank design indirect, I doubt a "mining pump" would be required to pump the flow you mentioned, unless a Grundfos 26 99 or Taco 0010 is considered a mining pump?

    Weil shows a 8.8' pressure drop at 11 gpm for the AqyaPlus 45 tank.
    The Caleffi tanks have 1-1/2 coils and very low pressure drop also, by the way

    And true 16 gpm in 1" copper would run just under 6 fps velocity, doable but not recommended, 1-1/4 would be a better choice.

    I would like to see the system operated with a delta T, then a delta P auto adapt circ, and observe performance differences, especially on the indirect. I'll send a 132 quick setter for the indirect to observe flow rate under the different pump operations.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • hot_rod
    hot_rod Member Posts: 14,785
    I'm agreeing with you on this one, although I believe a mini Magna or Viridian could pump that flow with minimal power consumption.

    I also qualified most if not all my post with a "reasonable" pump size.

    I'm not sure when you cross the line from reasonable to "mining pump"
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    edited August 2015
    @Hatterasguy we have the setting on 2 middle setting...Had the surprise of finding out the customers salt water fish equipment leaked onto our brand new pumps and connections for the indirect. Spent an hour with white vinegar cleaning the build up off the new equipment...Not good...
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
  • 4Johnpipe
    4Johnpipe Member Posts: 479
    According to the chart in HTP I&O manual. The higher flow will lower the delta T of the temp rise in the boiler. I would expect that to widen the S & R delta T. I may try it as we still have to install some Heating Edge baseboard and wire the heating zones to the existing mess...
    LANGAN'S PLUMBING & HEATING LLC
    Considerate People, Considerate Service, Consider It Done!
    732-751-1560
    email: [email protected]
    www.langansplumbing.com
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