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Does anyone know of any piping method

Harvey Ramer
Harvey Ramer Member Posts: 2,239
or device that would be able to produce mutiple mixed water temps at the same time while only using one circulator. It seems there should be a way. This has been nagging me for 5 years and I need to either forget about it or figure it out.


  • icesailor
    icesailor Member Posts: 7,265
    Multiple Mixers:

    Multiple thermostat mixers and very complicated piping.
  • Al Corelli_2
    Al Corelli_2 Member Posts: 395
    Try This

    Tie all the returns in to one properly sized pump.

    Use thermostatic mixers on the supply side to get your temps.

    Balance very carefully.
    Al Corelli, NY

  • Zman
    Zman Member Posts: 7,542

    The tekmar controls can do this. The tn4 335 controller will cycle the zone valves to provide a lower average temp to a particular zone. These work well in houses with different types of infloor heat.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • method

    after circ you would have to split line and use a thermostatic mixing valve to line you want to change temp to......hope this helps
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    Here is the best I came up with so far.

    I am trying to create a pressure equallibriam across both legs of the ladder in the secondary loop with the expansion tank. The secondary circ creates a pressure drop across the system to the mix port of the mixing valve. Instead of hydraulicly seperating the primary and secondary loop, I put a bypass bullnosed into each side of the ladder to induce a slight pressure drop on the system return isolate the boiler head from the Hydronic Ladder and create a slight pressure rise on the system supply. I figured to keep the pipe size the same on both legs of the ladder and the bypass.

    Pick it apart, scructinize and suggest. This is theoretical at this point.

    By the way, the software didn't regonize what I was trying to do.
  • Gordan
    Gordan Member Posts: 891

    There is no way, with a single circulator, to have the water want to go both from A to AB and from B to AB (which is what you need for mixing) unless the circulator is pumping away from the AB port - that is, it's on the mixed circuit. Just think about it. The pressure differential goes the other way.

    The only way multiple temperatures could be obtained with a single circulator is to have the valve divert some of the branch return between "direct" back to system, and a heat exchanger where it tempers the branch supply before returning to the system. The reason this would work is that it only requires heat, not hot water, to flow - and for that, you only need a temperature differential and not a pressure differential.

    Not suggesting that using heat exchangers makes any sense, mind you. Especially since they're more expensive than circulators. But it would "work."
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,506
    First of all...

    Kudos for thinking outside the box and experimenting. Secondly, how in the heck did you draw that on the flow pro design software? I've played with that for days, little frustrating.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    The software is a little finicky.

    Bascally you draw all your walls first, put in your windows and doors. Right click on anything to specify the properties of any and all components, walls,floors, windows, roof, ect... Drop in all the hydronic equipment and connect it all with pipe. Be a little cautious though. The software uses the IBR infiltration method. This might be ok for houses built in the 50's but the new houses are a lot tighter. I don't think it does good on radiant either.

    It's a cool program though.

    Back to the piping. I have a mechanical engineer buddy. I'm going to get him to simulate some flows and such. He has access to computer programs I could not begin to afford.
  • icesailor
    icesailor Member Posts: 7,265
    IBR and calculations:

    " "Be a little cautious though. The software uses the IBR infiltration method. This might be OK for houses built in the 50's but the new houses are a lot tighter. I don't think it does good on radiant either." "

    What is the problem with IBR calculations? I've always found them to be far more accurate for hydronic situations than any program based on ACCA Manual "J" or a lot easier to use than ASHRA.

    I've owned over six ACCA Manual "J" and ASHRA based programs in my time. I found that the IBR program booklet that taught me was the easiest to understand and use. They point out that building orientation doesn't matter in heating because the sun doesn't shine at night. There is no solar gain at night. ACCA says to put more outlets (for cooling) in south facing rooms. Great idea. On a cloudy, cold day, the back of the house will be cold and the front will be hot. With the prevailing winds blowing from the North. With the thermostat in a south facing room, the infiltration on the north side will be driving the heat to the south. Fine for AC. Horrible for FHA or FHW.

    All those programs are moot when it comes to a FHA/AC that has a 12"x18" return duct over the furnace below and flex duct run to all the other rooms. With all returns going back through the house to the one return. A serious case of COPD.
  • Gordan
    Gordan Member Posts: 891
    You're cheating... that's two circulators! ;-)

    I may have to eat my words yet. Only, I don't think that this will work unless you remove the last rung in the ladder - the one right under the expansion tank. And use closely spaced tees in order to hydraulically isolate boiler flow from system flow. Then P1 creates no pressure differential across the mixing valves but merely circulates water through the boiler and the tees, P2 creates pressure differential between both cold (directly) and hot (through closely spaced tees) ports of the mixing valves, and their outlets, and the mixing valves divert that pressure differential between hot and cold legs, creating more or less flow through the closely spaced tees but constant flow through the system. Marvelous! There's even a built in reverse return aspect, balancing pressure drops along the ladder.
  • Gordan
    Gordan Member Posts: 891
    Here, like this

    Pardon the crude drawing.
  • Gordan
    Gordan Member Posts: 891
    edited February 2012
    Better yet...

    It strikes me that it is more important to balance pressure across each mixer to give them best authority, rather than balancing the total pressure drop across circuits. Small difference anyway, given short lengths of plumbing involved.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239

    This one has a strong possibilty of working. I like the fact that on this one you are pumping away. The mixing valves are going to have various pressure drops. I think the one with the highest pressure drop (most flow) should go on the farthest rung.
  • Harvey Ramer
    Harvey Ramer Member Posts: 2,239
    I don't disagree with you

    on house orientation. I was thinking along the lines of infiltration. My understanding of the IBR method is that X feet of exterior wall = X factor infiltration. The program was developed back when houses didn't have house wraps and such. It is my understanding that it hasn't been updated to accomodate the new houses.

    I may be dead wrong about this. It may only have been a biased opinion trying to promote wrightsoft. You have many years of experience on your side. I have to depend on gathering knowledge from those who have been there.
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