[TRNSYS-users] Active Layer (Slab) Flow Requirement Conflicts with Type 1669 Control Scheme

[Bradley Painting]

I received a suggestion to use a Type 1669 controller for a radiant slab,
and it seems to work well (thanks Ben Heymer). However, right now I am
using it to modulate temperature, but what I would really like to do is
modulate the flow rate through the slab because I have a variable
(uncontrolled) input temperature. The problem is that TRNSYS will not allow
me to decrease the flow rate much below 2,000 kg/hr based on the size of my
radiant floor.

(Error Message: "Specific fluid mass flow of active layer in surface 9
below minimum value of 6.74 kg/m2h Please, increase the minimum mass flow
rate or use the autosegmentation feature of TRNBuild for subdividing the
surface").

The proportional controller will inevitably fall below this rate because it
will ramp down to zero when no heating (or cooling) is needed. Is there a
workaround for this? I looked into the autosegmentation feature and it
doesn't seem to subdivide the surface at all, and I'm not sure how this
would help. Thanks again.

-- 

Brad Painting

Master of Science Candidate, Renewable Energy Engineering

Department of Technology & Environmental Design

Appalachian State University

Boone, NC  28608
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