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Adding second hydronic loop to system

Steve GarsonSteve Garson Posts: 584Member ✭✭
I want to add a second hydronic loop to add a zone to the heating system. Can I simply install a 3/4-inch tee before the circulator to feed the second circulator with flow-check?  Or do I need to create a manifold?



Steve Garson

Newton, MA
Steve from Newton, MA
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Comments

  • Ron Jr.Ron Jr. Posts: 524Member
    Is the first zone 3/4 inch ?

    Does the piping come out of the boiler in 3/4 too ?  Can you post a pic of the existing setup ? You could just add a tee before the circ but the smaller piping might limit the BTUs to the zones . Depending on how big the zones are . 
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Photo

    The pipe from the Spirovent is 3/4-inch.  I was thinking of inserting a Tee before the circulator. The question being whether the Tee can carry the water straight through to the present loop, with the new loop as the take-off.  Or would it be better to install the Tee so that both loops were connect to the Tee and an elbow.  Present loop heats 9000 BTU with baseboard.  New loop will heat 12,000 BTU radiant loop with separate circulator and tempering valve to keep the water temp at the correct level.



    This is actually the output of a Everhot heat exchanger connected to a steam boiler.  Have confirmed that the heat exchanger has plenty of excess capacity,



    Steve
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    Post edited by Steve Garson on
    Steve from Newton, MA
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  • SWEISWEI Posts: 4,653Member ✭✭✭✭
    Sketch?

    The addition of a tempering valve makes me want to see a bit more.



    thanks~ 
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    Piping Diagrams

    Attached are two piping diagrams.  One is the present configuration with a single hot water loop to a baseboard zone.  The second is the one that I am looking for feedback, which is the addition of a zone for the radiant zone, which presently, is running off a coroded Combicore (my second in nine years!)
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    Steve from Newton, MA
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  • TomTom Posts: 292Member
    Possible

    Steve,



    In the second pic, I would swap Mixing valve with circ so it mixes first then circulates through the tubing. But it should work other than that from what I saw when I looked.
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    The Tee

    Thanks for your insight. My final question is the configuration of the Tee that I will be installing. If I install it so that the flow is straight through to the present circulator, it is an easier plumbing job. My instinct tells me that the correct way is to install the Tee with the flow diverting to both ends of the Tee into elbows and then to the circulators.



    Does it matter? Or is my instinct correct?



    Steve
    Steve from Newton, MA
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    why split before the pump?

    use two zone valves and split after the circulator but before the mixing valve.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Using one circulator instead of two

    My concern is that the present baseboard loop is very short, as in ten feet from the circulator, with twenty feet of baseboard.  The radiant loop is fed by 35' feet of 3/4 pipe on the feed and on the return.  So I think the water would take the shortest path if both zone call for heat, with the radiant not getting much water.



    Thoughts?



    Steve
    Post edited by Steve Garson on
    Steve from Newton, MA
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  • TomTom Posts: 292Member
    You Got it

    Steve,



    I would say you have a good plan, the second pic with the swap of the circ and mixing valve will work fine. Piping is pretty forgiving and what you have if it's easier should work great.
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    Have you checked your required flow rates?

    and compared them to the output of the pump? I was once a pump addict. I wanted a pump for every zone. I had no faith in pump curves. The thing is why run the extra pump if one will do the work? Yes water is lazy and takes the easy route. The response time on the fin tube should have it off much of the time with the radiant doing the slow and steady. I am looking at the photo you posted and it looks easier to cut in after the circulator then before it. `Both methods will work. I am just offering a different perspective.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    I just found your other post in radiant heating

    that little copper coil may not like the velocity you are asking using two pumps. Also you are supplying it with heat from only one taco 007 pumping condensate, how is that going to handle the output? I am assuming from the photos you are a DIYer and you did that piping yourself right?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    I just found your other post in radiant heating

    that little copper coil may not like the velocity you are asking using two pumps. Also you are supplying it with heat from only one taco 007 pumping condensate, how is that going to handle the output? I am assuming from the photos you are a DIYer and you did that piping yourself right?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • ChrisChris Posts: 2,869Member
    First Off

    Radiant and baseboard should have different design delta-t's. The first question is what is the required flow rate needed for the baseboard and what is the required flow rate for the radiant? Your main better be able to carry the total flow rate before you split off into that tee.



    Second, should have 12" of straight pipe before you enter those circulators.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
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  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    He has a mixing valve for the radiant

    the zone valves would be teed before the mixing valve and the return for the baseboard would be after the mixing valve. That way the radiant gets radiant temps and the baseboard gets baseboard temps. It also means only low voltage wiring and no additional relays to turn on any other circulators.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Flow Capacity

    The Everhot RH-6 is rated at 6GPM with 35,000 BTU capacity. The GPM is based on 100* rise at 200* boiler temp.
    Post edited by Steve Garson on
    Steve from Newton, MA
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Heat load on baseboard loop and radiant loop

    For the baseboard loop: 18-feet of baseboard with a heat-loss of 13,000 BTU. This room takes almost no time to warm up after a call for heat.



    The radiant loop has 13,000 BTU of heat loss and four loops of Onyx under the floors
    Post edited by Steve Garson on
    Steve from Newton, MA
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    Flow rate and BTU

    Btu/hr Q = GPM x 500 x Delta-Temp



    26,000 BTU = GPM x 500 x 20* = GPM x 10000



    GPM = 26,000/10,000 = 2.6 GPM



    Everhot RH6 Specs: 35,000 BTU at 6GPM



    Delta-Temp = 35,000/(6GPM x 500) = 11.66 delta temp



    5GPM gives a 14* delta temp



    4GPM gives a 16.5* delta temp



    I'm not sure where this is going, since the Everhot specs say there is a 100* rise with 200* water.
    Steve from Newton, MA
    · ·
  • ChrisChris Posts: 2,869Member
    Disagree

    With your flow rate. Formula is correct for a 20 degree delta-t but that radiant should be running on a 10 not a 20.



    Baseboard Flow = 1.3gpm

    Radiant Flow = 2.6gpm
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • ZmanZman Posts: 2,206Member ✭✭✭
    Gpm

    Chris is correct. Your radiant will pull a little less if you are mixing. Either way you are under the 4 gpm your 3/4" pipe can handle. In a perfect world you would pipe this reverse/return or increase your header size for a design of 2 fps. I think it will work as you are planning. You will have trouble finding a circ that will go down low enough for you baseboard loop, you might consider a balancing valve.

    The circ on your mixing loop needs to be in the mixing loop. The way you have drawn it, the circ will dead head as soon as the loop comes up to temp. All circulation will stop.

    As Chris mentioned, do not put 90's and tees near the inlet side of the circs. I think the rule is 12 pipe diameters. In your case that would be 9".

    Don't worry about the 100 degree rise from everhot. That is just the number they are using for their gpm calcs. Gpm x delta t x 500 =btu/hrs will alway be the formula. They are basing their gpm on a delta t of 100 . This is for dhw production.. Your design will be different since you are using it for heating.

    Happy piping,

    Carl
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    Thanks guys I missed the mistake in the drawing

    the circulator is on the wrong side of the mixing valve for the radiant zone. It needs to be inside the radiant side of the loop. Then of course you would need to use two circulators. I was thinking since it was such a small zone you were using a manual mixing valve to roughly set the temp in the radiant zone, since it is an automatic valve the circulator needs to be moved.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    Circulator location

    Are you suggesting that the circulator for the radiant should be to the right of the of the mixing valve on my drawing?
    Steve from Newton, MA
    · ·
  • ChrisChris Posts: 2,869Member
    May I Suggest

    The attached for some reading. Should answer all your questions.
    pdf
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    Mixing In Hydronics.pdf
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    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Circulator location

    Chris:



    Interesting reading.  Everything I've learned has the circulator located right after the expansion tank & air eliminator.  Is locating it as described in that PDF, downstream from the mixing valve flow, the normal and customary design approach?  Or this this  subject with much debate?



    Steve
    Post edited by Steve Garson on
    Steve from Newton, MA
    · ·
  • ChrisChris Posts: 2,869Member
    edited July 2013
    There Is Zero Debate

    That the radiant supply circulator must be installed after the mixing valve. The question is, do you need to provide boiler protection from low water temps, ie, less then 140 for a cast iron boiler? If so, then your piping approach should be primary/secondary.
    Post edited by Chris on
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    Piping Approach

    Yes, this is primary-secondary piping.  No radiant water is getting to the boiler .I checked the instructions for the Taco mixing valve and see that you are 100% correct.  I am fixing work done by a "pro" who did not install the circulator and mixing valve as you describe. 



    I think I finally have all the info I need.  Thanks for catching that error.  I will post a new piping diagram with the final design.  I'm actually going to use a plumber. I've just learned that there are plenty of people who don't truly know what they don't know.



    Steve
    Steve from Newton, MA
    · ·
  • ZmanZman Posts: 2,206Member ✭✭✭
    EDR

    Steve,

    I looks like you are on the right track. Chris makes a good point about making sure you are protecting the boiler from condensation. Has anyone compared your steam radiator EDR values to the size of you boiler. In other words, does your boiler have enough capacity to service your existing steam system and your new system?

    Carl
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Final Piping Design

    Attached is the final piping design, based on all the generous pros who have offered their insight.  My boiler, a WG SGO-4 with a Carlin EZ-Gas has plenty of capacity,  On a design day in the cold of the winter, it runs no more than 20% of the time.  Our house is very well insulated and sealed from air leaks.  The boiler size is based on steam radiator EDR, from the days of no insulation and leaky windows.



    If anyone has any more suggestions, I would love it.



    Steve
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    Post edited by Steve Garson on
    Steve from Newton, MA
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  • ChrisChris Posts: 2,869Member
    Won't work

    Need a another pump and the piping is wrong.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • SWEISWEI Posts: 4,653Member ✭✭✭✭
    edited July 2013
    Plenty of capacity

    How much, in relation to your design-day heat loss?



    And I don't think I'm 100% clear -- this is purely a hot water system with no steam?
    Post edited by SWEI on
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    Heat Loss and Another Circulator?

    Chris, The drawing does not display the circulator that feeds the hot water from the steam boiler to the heat exchanger, since that is already installed.  Do I need another?  if so, where?



    For heat loss, the building heat loss is 75,000 BTU.  The boiler is steam; WM SGO-4, with a steam rating of 108 MBH and DOE heating capacity of 144MBH.  The steam radiators have a total of 461 square feet of radiation.
    Steve from Newton, MA
    · ·
  • ChrisChris Posts: 2,869Member
    edited July 2013
    See Attached

    This is how I would pipe it.
    pdf
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    Everhot.pdf
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    Post edited by Chris on
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • TomTom Posts: 292Member
    My bad

    Steve,



    Chris is right I didn't notice it was an everhot heat exchanger when I told you that it would work, I assumed the circle was a boiler with a built in circulator, my bad. His diagram is probably the best design not the cheap and easy way but will work without fail and be the least problematic.
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    For the size of system you have

    I do not see why your newest diagram would not work. I just would suggest changing the circulator for the steam side to a B&G 100 Bronze.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • ChrisChris Posts: 2,869Member
    edited July 2013
    How Would He Get Flow

    To the secondary loops his way? He specifically said he was primary/secondary piping.
    Post edited by Chris on
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    it is not primary secondary if you look at his other posts

    He is using the everhot as a heatexchanger. He has a high temp loop and a low temp loop. He is using a taco 007 to push the water from the steam boiler through the everhot. He is piping the hot water loops off the side that would be the domestic coil.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • Charlie from wmassCharlie from wmass Posts: 3,017Member ✭✭✭
    I would usually put the mixing valve

    and the circulator on the return from the radiant loops with the circulator pushing into the mixing valve.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
    https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating
    · ·
  • ChrisChris Posts: 2,869Member
    Exactly

    It has a coil in it. The pump from the steam boiler is only moving btu/ht to the tank. Need one to take it away. The way he has is piped water would never leave it.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • ChrisChris Posts: 2,869Member
    Huh?

    Why would water move through the cold water side of the mix valve and give you the proper water temp? Pondering the flow through my mind and all that return water would beat feat for the boiler. It has no reason to go North..
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
  • Steve GarsonSteve Garson Posts: 584Member ✭✭
    edited July 2013
    Diverter Tee Approach

    Chris,



    Just so I can understand, why would BTUs not leave the Everhot with my piping diagram pulling water from the Everhot? There are two circulators that I thought would take the BTUs away, one for each zone. I'm not challenging your design, but interested in understanding the reason. By the way, I appreciate the time you've given me on this project. This thread has become an interesting one in many ways. Do you have a preferred brand of diverter tees?



    Steve
    Post edited by Steve Garson on
    Steve from Newton, MA
    · ·
  • ChrisChris Posts: 2,869Member
    Pri/Sec

    You specifically stated that you were pri/sec

    piping. Your diagram is not proper pri/sec

    piping. Water is dumb when both zones call,

    where do you think all the flow is going to go

    piped as you have it?
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    · ·
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