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New Boiler Circulator Speed

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David_16
David_16 Member Posts: 105
edited March 6 in THE MAIN WALL
I recently had a Weil McClain ECO Tec 110-H boiler (modcon) and indirect HW tank installed.

I have Taco-0015 3 speed circulators that are all set to medium by the installer. Apparently, there's also an internal Taco-0015 that should be set to high according to the manual.

House is 2 floors, 1800 square feet, fintube baseboard heating. Zone 1 is same floor as the boiler and thus is a relative short run and doesn't run much. Zone 2 is a floor above and is a relatively long run and runs frequently. Zone 3 is DHW and the WH is right next to the boiler. When Zone 1 is running, the boiler in temp is usually about 3-5 degrees less than boiler out temp.

Should I drop any/all of the circulators down to low? As I understand it, benefits might be less noise (I do find the whole system to be louder than I expected), better for pipes, less electricity and maybe side benefit of lower return temp so that I will condense more. Negative might be the rooms at the end of the run get a lower water temp and will be colder? What about the circulator for the WH? I could be wrong on all of this I suppose.

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  • LRCCBJ
    LRCCBJ Member Posts: 121
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    Turn zone 1 down to low.
    Leave zone 3 on medium. Usually the circulator for DHW is run at the highest speed for the best recovery (keeps the temperature in the coil higher). But, if you have enough HW, it can stay at medium.

    Measure the supply and return temperatures on zone 2. If the speed is too low, the room at the end of the loop will not be comfortable. The difference in the temperatures will tell which way to go.
    David_16MikeAmann
  • David_16
    David_16 Member Posts: 105
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    LRCCBJ said:

    Turn zone 1 down to low.
    Leave zone 3 on medium. Usually the circulator for DHW is run at the highest speed for the best recovery (keeps the temperature in the coil higher). But, if you have enough HW, it can stay at medium.

    Measure the supply and return temperatures on zone 2. If the speed is too low, the room at the end of the loop will not be comfortable. The difference in the temperatures will tell which way to go.

    I've got plenty of DHW with it on medium. With the hot water tank set to 140 and a mixing valve at 120, I can fill up a large bathtub continuously so don't see any need for more/faster hot water.

    Will move zone 1 to low.

    When you say measure supply and return temperature on zone 2, I'm not exactly sure what you mean. The boiler screen has reading for boiler in/out. There's also a section for supply in/out, but that just says open/open. There's also a flue temp that doesn't show on the boiler screen, but does show in the app if I connect via BT. So am I supposed be looking at the boiler in/out readings?

    With zone 2 circulator on medium, it's been about 3-4 delta between in and out. I changed it to low earlier for a circuit and maybe that increased by 1-2, not sure. If that's the number I'm looking for, I'll have to watch things a bit more closely. What delta am I looking for before I should run the circulator at a higher speed?
  • Joe Mattiello
    Joe Mattiello Member Posts: 707
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    You’re fortunate to have a three speed pump to best adjust flow rate to satisfy load.
    you’ll need to determine load by measuring baseboard and then you’ll be able to determine your pressure drop based on determined flow through each zone. 
    Keep in mind, faster isn’t better, and could lead to erosion corrosion by exceeding recommended maximum velocity through the piping.
    if you need help with that, contact Taco tech support at 401-942-8000
    Hopefully this was helpful 
    Joe Mattiello
    N. E. Regional Manger, Commercial Products
    Taco Comfort Solutions
    David_16
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,544
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    With a CI boiler you would measure the supply temp and return temp and you would want 20 degrees maximum.

    Mod cons don't care. You can cut the flow for a loop until you get 30-40 degrees. With a wider TD you may get less heat. So what you want is to run the pump at the slowest speed that gives you the heat you need.

    You need to measure the supply and return at the zone loop not at the boiler. mod cons don't care about low return temps
  • David_16
    David_16 Member Posts: 105
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    With a CI boiler you would measure the supply temp and return temp and you would want 20 degrees maximum.

    Mod cons don't care. You can cut the flow for a loop until you get 30-40 degrees. With a wider TD you may get less heat. So what you want is to run the pump at the slowest speed that gives you the heat you need.

    You need to measure the supply and return at the zone loop not at the boiler. mod cons don't care about low return temps

    How would I measure the supply and return at the zone loop? I'm not even sure where that is or if I'd have some sort of tool to do that.
  • LRCCBJ
    LRCCBJ Member Posts: 121
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    David_16 said:



    When you say measure supply and return temperature on zone 2, I'm not exactly sure what you mean. The boiler screen has reading for boiler in/out.

    With zone 2 circulator on medium, it's been about 3-4 delta between in and out. I changed it to low earlier for a circuit and maybe that increased by 1-2, not sure.

    Based upon the above info, you certainly can run zone 2 at the low speed. It will not affect comfort.

    David_16
  • PC7060
    PC7060 Member Posts: 1,160
    edited March 8
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    David_16 said: How would I measure the supply and return at the zone loop? I'm not even sure where that is or if I'd have some sort of tool to do that.
    You can buy inexpensive strap on thermometers from supply house.com. You should have a thermometer on the Boiler measuring the SWT (output) already so may need just one. 

    The temp gauge on right (return side)  is strap on, left one on supply side is plumbed temp/pressure gauge.  


  • David_16
    David_16 Member Posts: 105
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    PC7060 said:


    David_16 said: How would I measure the supply and return at the zone loop? I'm not even sure where that is or if I'd have some sort of tool to do that.

    You can buy inexpensive strap on thermometers from supply house.com. You should have a thermometer on the Boiler measuring the SWT (output) already so may need just one. 
    I have one thermometer. It reads about the same as the Boiler Out temp on the LCD. So what's the Boiler In temp on the LCD screen? That's not the number I'm looking for without needing a strap thermometer?

    And if I did get one, I see them on Amazon too, but I do have a supplyhouse about a mile away, but couldn't figure out of anything is actually in stock in the store.

  • LRCCBJ
    LRCCBJ Member Posts: 121
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    David_16 said:


    And if I did get one, I see them on Amazon too, but I do have a supplyhouse about a mile away, but couldn't figure out of anything is actually in stock in the store.

    You already have the gauges you need. There is a gauge on "heating water outlet" and there is a gauge on "heating water inlet".

    Get the system stabilized for zone 2 and read the two gauges. The difference is what we are interested in to determine the proper speed for zone 2. You previously stated four degrees. That does not sound like the system is stabilized yet but based upon only this info, you can run the circ at the lowest speed for that zone.
  • David_16
    David_16 Member Posts: 105
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    LRCCBJ said:

    David_16 said:


    And if I did get one, I see them on Amazon too, but I do have a supplyhouse about a mile away, but couldn't figure out of anything is actually in stock in the store.

    You already have the gauges you need. There is a gauge on "heating water outlet" and there is a gauge on "heating water inlet".

    Get the system stabilized for zone 2 and read the two gauges. The difference is what we are interested in to determine the proper speed for zone 2. You previously stated four degrees. That does not sound like the system is stabilized yet but based upon only this info, you can run the circ at the lowest speed for that zone.
    There's only 1 physical gauge that I can read, but the boiler out/in on the LCD is all I really need to look at? I thought someone earlier referenced that it should be read elsewhere in the system.

    And yes, with the zone 2 circulator on low, it's definitely been stable for a while and running at 4-5 degree difference. Maybe it was a degree or so less delta on medium. I haven't looked at the zone 1 delta, but I guess I should look at that too at some point, but with it on the same floor and a short run, I can't imagine it would be more. I thought the typical out/in difference was closer to 10, so I've always been wondering why it's so little in my system.


  • PC7060
    PC7060 Member Posts: 1,160
    edited March 9
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    David_16 said:


    I have one thermometer. It reads about the same as the Boiler Out temp on the LCD. So what's the Boiler In temp on the LCD screen? That's not the number I'm looking for without needing a strap thermometer?

    And if I did get one, I see them on Amazon too, but I do have a supplyhouse about a mile away, but couldn't figure out of anything is actually in stock in the store.

    Strap on works well to measure the return for each Zone; you can buy one for each zone for not much $
    I bought the Bluefin GTH25-250-CL (~$8) but there are several options
    https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=Strap On Thermometer
    https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=Clamp-On Thermometer
  • David_16
    David_16 Member Posts: 105
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    PC7060 said:


    Strap on works well to measure the return for each Zone; you can buy one for each zone for not much $
    I bought the Bluefin GTH25-250-CL (~$8) but there are several options
    https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=Strap On Thermometer
    https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=Clamp-On Thermometer

    And where would I strap them exactly?


  • LRCCBJ
    LRCCBJ Member Posts: 121
    edited March 9
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    David_16 said:


    There's only 1 physical gauge that I can read, but the boiler out/in on the LCD is all I really need to look at? I thought someone earlier referenced that it should be read elsewhere in the system.

    And yes, with the zone 2 circulator on low, it's definitely been stable for a while and running at 4-5 degree difference. Maybe it was a degree or so less delta on medium. I haven't looked at the zone 1 delta, but I guess I should look at that too at some point, but with it on the same floor and a short run, I can't imagine it would be more. I thought the typical out/in difference was closer to 10, so I've always been wondering why it's so little in my system.

    My apology. I saw the photo above (by PC) and thought it was your setup.

    If the temperature in all the rooms on zone 2 is close to the same (and the last room is not too cold) just leave it on the low speed. You really don't need to spend time and money on experimentation. If the delta climbed to near 20 we could have another chat about it.

    David_16
  • PC7060
    PC7060 Member Posts: 1,160
    edited March 10
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    You define the answer to your question; strap the gauge onto the return for the pump you are trying to assess / adjust speed. 

    From the photo you provided I’d strap thermostat to the vertical return below the circulator of interests right below the shutoff before connection to main return.  

    Edit: The return is the lower of the two black manifolds. 
    David_16
  • hot_rod
    hot_rod Member Posts: 22,158
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    The delta T through a heat emitter will change based on the load of the space where the emitters are

    Expect a wide delta in a cold room on start up the delta will tighten as the room warms.

    The delta is an indication of the amount of heat being transferred

    If you know the flow and measure the delta
    Put it into the btu formula 

    500 x flow x delta t

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • PC7060
    PC7060 Member Posts: 1,160
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    By the way, that install looks very nice. 
    David_16
  • David_16
    David_16 Member Posts: 105
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    PC7060 said:
    By the way, that install looks very nice. 
    Thanks! I don't know much to look for,but I thought they did a nice job. Didn't seem to cheap out anywhere, I see the boiler expansion tank is supported and those 3 speed tacos are not cheap.  I see people post their installs elsewhere and always seem to get skewered so hopefully this company did a nice job.