[EnergyPlus_Support] High-Temp Radiant System coupled with dummy primary system (how???)

["Kristin Field" <fieldkm@xxxxxxxxx>]

Hi, I'm trying to model a zone that has a high-temp. radiant system
only.  Basically, it is a semi-conditioned space - a space that has
very low heating setpoints and no cooling setpoints.  The only
elements providing heat to meet the heating setpoint should be these
tube heaters.  Oh, and it's single-zone.

In the EP documentation, the high-temp. radiant systems are described
as supplemental zone equipment to a primary system.  I have tried
using the purchased air system and also creating a "dummy" system
(zero energy, flows, very low setpoints, etc.), and neither one works.
 In the purchased air system with very low setpoint, the sizing
algorithm determines that there's no heating load, so the radiant
system isn't deployed.  In the compact DX system with very low
setpoints and zero energy (but not zero flows), the same thing
happens.  In the compact DX system with low setpoints, zero energy,
and zero flows, it terminates the run due to flows of zero.

Can anyone tell me how to accomplish what I want to in this model?  A
tube-heater-only heating system.

On a related note, this got me thinking about another question:
pretending that I wanted to use a high-temp. radiant system as it was
intended, as a supplement to a central HVAC system, how does EP decide
when to deploy the central heating and when to deploy the radiant
system (as long as they have the same setpoint schedules)?  I know
that the controller gives priorities 1 and 2, but if the equipment is
autosized, then does the auto-sizing take into account that there is
priority 2 equipment there and size the priority 1 equipment to be
smaller?  If it doesn't, and it sizes the priority 1 equipment to meet
all the heating load, then why would the 2nd priority equipment ever
be called?  This is just something that I would be interested to know.

Thanks for the help!

Kristin Field



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