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Home run or monoflow system?

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blimey
blimey Member Posts: 5
in Radiant Heating
We are installing radiators on our on-demand hot water system that already supplies radiant floor heat to one room and domestic to the house. We need to know the best type of system. We had originally thought that monoflow would suffice, but wonder if it would. We are only installing the radiators in two bedrooms and one bathroom. We thought if they were run in series on one loop that it would create enough heat, but we are reading that the Home run might give better heat. The issue is balancing the system since one bedroom is very close to the pump/manifold and the two others span a distance of 15' and then 30' away. If we were to do the Home run system, how to balance the flow so it doesn't take the path of least resistance? Can you use TRV's?

And can we do a mono flow system and achieve the same output as the Home run system?

Thanks

Comments

  • SWEI
    SWEI Member Posts: 7,356
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    Monoflow was a wonderful thing in its day

    and it saved quite a bit of T&M when systems were built out of threaded pipe.  While an elegantly simple concept, they are quite unforgiving of poor engineering.  Even when properly designed and installed, they make purging more difficult and still have the series loop emitter problem.



    In the modern world of barrier PEX, you would be far better served by a parallel piping arrangement.  Home-run manifolds, reverse return, and direct return each have their advantages but if you install TRVs at every radiator they will all work well.



    http://www.caleffi.us/en_US/caleffi/Details/Magazines/pdf/idronics_8_us.pdf will explain all of the above if you want to understand more.
  • blimey
    blimey Member Posts: 5
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    where to get a manifold for a homerun system?

    We are wondering where we could buy a manifold for our on-demand, radiator homerun system? Can we get them at any plumbing supply place?
  • SWEI
    SWEI Member Posts: 7,356
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    Manifolds

    are available from any heating supplier, online or local.



    What is on-demand?  Are you trying to use a tankless water heater in place of a real boiler?
  • blimey
    blimey Member Posts: 5
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    on-demand or tankless hot water heater

    Yes, it is a Takagi on-demand hot water heater that is used for radiant floor heating and domestic hot water, and an extra leg on the manifold would be for the radiators. Would the Home run system still be the best to use? Or the mono flow?
  • knotgrumpy
    knotgrumpy Member Posts: 211
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    Is your domestic hot water

    sharing the radiant tubing, or is it separated by a heat exchanger of some type?
  • blimey
    blimey Member Posts: 5
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    home run or monolog system

    there is a heat exchanger that will be providing heat for both the radiant floor system and the radiators, both on separate legs off of a manifold. The radiant floor heat has a mixing valve to reduce the heat that is needed for the radiators. We are planning on not exceeding 160 degrees in order to try and accomplish our needs. There is also a mixing valve for the domestic water side.



    Should we do mono flow or home run?
  • blimey
    blimey Member Posts: 5
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    I forgot to add

    which you may have already discerned, that the domestic is also heated by the heat exchanger.

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