boiler, un-pressurized tank, external HXer, instant DHW

in hot water Posted By in hot water, Oct 29, 2011 at 4:34 AM

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  1. in hot water

    in hot water
    New Member 2.

    Jul 31, 2008
    SW Missouri
    Here is one concept we will show in I-dronics 10. This provides all the HXers outside the tank, and provides instant DHW with a tankless gas or electric for non-burn days. Or weeks :)


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  2. tom in maine

    tom in maine
    Minister of Fire 2.

    Apr 4, 2008
    Searsport, Maine
    I'll go a step further and suggest losing all the hx and pumping treated tank water.
    Our standard way of doing this, since unpressurized heating systems do scare some people, is to use a single coil as the interface with an unpressurized
    tank such as ours.This is used to input and remove heat from the tank.
    This eliminates two pumps, two plate hx and half of the air removal/expansion hardware.

    The system at my house, uses only a DHW hx directly from the tank. A bronze 007 pumps from the tank to the 5 zone radiant distribution system. I use a 009B for the boiler since I plumbed with 1" copper and was not sure about the boiler heat output. (It peaked at 120K last night at 7.3gpm) The return lines are submerged so there
    is no water noise. We use all non-ferrous materials, so the water is not treated.

    Coils are not inexpensive, but they are passive devices and when designed properly, do function very efficiently. We find our DHW hx operates in the high 90's%. The space hx are similar.

    My 2 cents worth. Now that the heating season is upon us up here. (6" of snow tonight and a Nor'easter!?)
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