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Re: [EnergyPlus_Support] Question: Radaint cooling slab and configuraion
2. It is likely that there is a problem with the way your radiant loops are
connected. Do you see any warnings about node connection errors in the err
file? HVAC Diagram can draw the RadLoHydrHeatCoolAuto (radiant heating and
cooling) and RadLoTempHydrTermReheat (radiant heating with a terminal reheat
air loop) example files, so it should be able to draw your system. Compare
your input with these two examples to see what the problem might be.
3. The air system should be the priority 1 for both heating and cooling,
because it may bring in ventilation air which adds to the load. The two system
are simulated in sequence according to the priority, so if the radiant is
priority 2 it should compensate for the ventilation load.
On 23 Apr 2004, at 16:45, zhen tian wrote:
> Hi, All:
> I have several questions for modelling a practical building.
> The building is a seven-story university building. The building system has the
> following features: 1. VAV reheat system (Four primary air loops); 2. Radiant
> slab colling system for controlling part of the building(Including three loops,
> two loops serve the perimeter zones and one loop serves the core zone); 3.
> Radiant heating panel for heating in perimeter zones. 4. The heating and cooling
> source from university chilled and hot water net.
> So could you help me with the following questions?
> 1. The radiant cooling slab supply water is the mixture of chilled water supply,
> return water from cooling coil and exit water from radiant slab. And the
> propotion of water mixture maybe is diffrent in three water loops. How can I set
> up this HVAC configuration? I mean the supply and demand side. For my model
> right now. I just set up a chilled water loop for the cooling coils and three
> other chilled water loops for the three radiant cooling slab. All these use the
> PURCHASED COOLING. Is it an acceptable method?
> 2. For my model, I just run the simulation and get the result from the .bnd and
> HVAC schematic file. From these files, it shows the air loops configuration is
> correct. And there is no error report for the water supply and demand side
> braches (chilled water for the cooling coils and chilled water for the radiant
> slabs). But the .svg file (HVAC schematic file) cannot display until I delete
> all the supply and demand side braches for the radiant slab system ,even the
> file size is normal. The abnormal thing is that the reslut from the file without
> radiant slab system (Normal VAV system) is almost the same with the result from
> the file with radiant slab system. I checkd the source location temperature. In
> the same, the chilled water flow for the radaint slab is zero. But from the zone
> and system sizing, it shows the water flow. So is it possible that the branches
> is not linked correctly?
> What should be the correct zone equipment priority? I set the radaint system as
> the priority 1 and Air Unit as the last, and this is different from the example
> file. Is it correct?
> I just run the simulation on January 1 in a cold weather and it only takes few
> minutes but when I run it only on July 21, it takes more
> than 10 hours. I do not know what is up. If the radiant slab system does not
> work in Jan, it should be the same for the cooling coil.
> Thanks a lot for helping me out!
> Best regards,
> David Tian
> Do you Yahoo!?
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> [Non-text portions of this message have been removed]
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Michael J. Witte, GARD Analytics, Inc.
EnergyPlus Testing and Support
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