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    Adding a Small Modine- (15 Posts)

  • ced48 ced48 @ 10:47 AM
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    Adding a Small Modine-

    I want to add a small Modine heater to the return line of a new Modcon install, purpose being to add some heat to a basement area, and knock down the delta-t some more. The old boiler use to keep the basement warm, with it gone, going to get chilly. The Modine will operate when ever the upstairs calls for heat. What is the best way to add the heater to the return line, without messing up the return flow to the boiler? The heater has .5 pressure drop at 1.3 gpm, my return line is 1", with about 5 gpm, serving a 2 split loop system. Thanks in advance for any help.
  • Dan Holohan Dan Holohan @ 4:16 PM
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    How about

    a couple of diverter tees? 
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  • ced48 ced48 @ 10:07 AM
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    So, how Do I -

    do this in a manner that will divert only a gallon and a half to the heater, and let the rest move along the main return? I don't want to constrict the return flow anymore than I need to-
  • Dan Holohan Dan Holohan @ 12:48 PM
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    Sizing Monoflo tees

    Here's a link to the Library: http://www.heatinghelp.com/files/articles/955/281.pdf

    This is from B&G's 1949 Handbook. You'll need to know the flow rate in the main and the pressure drop and flow needs in the branch to the heater. Include all the piping going to and from the heater when figuring pressure drop.
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  • ced48 ced48 @ 1:25 PM
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    Thanks, Dan-

    I'll see if I can make some sense out of it-
  • ced48 ced48 @ 2:52 PM
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    Well, I Didn't Think

    it was going to take an engineer to add this little heater, but maybe it will.
  • Dan Holohan Dan Holohan @ 3:25 PM
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    Ah, the lowly Monoflo tee.

    It is an engineered product. Sorry about the math. Some of this stuff just needs it to get it right.
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  • ced48 ced48 @ 4:54 PM
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    It looks Like-

    a Monoflo tee, placed on the return side is going to divert about half of the flow to the heater. This is going to give me about twice the flow I need. Does this mean a regular tee might be the best choice? Is there a way to calculate this?
  • Dan Holohan Dan Holohan @ 7:33 PM
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    With a standard tee the water will probably choose to stay in the main.

    Pressure differential is what makes ll of this work. The Monoflo tee, when properly sized, will move the water from the main through the heater. It may not be the exact amount you need but it should get you close.
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  • ced48 ced48 @ 8:58 AM
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    New Problem-

    How can I pipe this so I can isolate the Modine from the system if I find I don't need all it's heat, or only some of it, without adding head pressure?
  • Dan Holohan Dan Holohan @ 10:53 AM
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    After coming off the Monoflow tees

    you can pipe a bypass the same size as the feed to the heater. Do this just above the main. You'll need three full-port ball valves for this. Two of those ball valves will be on the feed and return to the heater and above the bypass line. This will be open when you want to use the heater. The third full-port ball valve that will be in the bypass line. Close it when you want to use the heater and open it when you don't.
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  • ced48 ced48 @ 7:40 AM
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    That Will Work-

    Thanks Dan-One last question, I hope, how much head pressure(drop) will the monoflo tee cause on it's own, not counting the diverted circuit ? I know the flow on the exit end will be the same as it enters, but will more energy be required to push it thru?
  • Dan Holohan Dan Holohan @ 8:44 AM
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    It depend.

    It works by creating a pressure drop in the main that's greater than the pressure drop in the branch circuit. How much depend on the flow rates in both and the pressure drop in the branch circuit. The B&G charts for this show what you get when you use one tee vs. two tees in the main. You then decided which option will get you as close as possible to what you need.

    I wish it was easier than that, but as I said, these things really are engineered products.
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  • Dan Holohan Dan Holohan @ 9:10 AM
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    Trying to find that four-part sizing chart.

    Lots of stuff in this office, though, and it's been years since I used it. If anyone else has it, please post. Thanks.
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  • Dan Holohan Dan Holohan @ 9:45 AM
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    Got it.

    They don't make the blue-ring tees anymore so don't select those.

    There's an explanation and then the charts. You begin with Chart 1 and work your way though 2, 3, and 4 with a ruler. You'll see your options when you get to the final point on Chart 4.

    Sorry this is as complicated as it is.
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