Plenums / Stratified Zones in Multiplexes

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NebK22
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Plenums / Stratified Zones in Multiplexes

Post by NebK22 »

Hi all,

I have a question regarding return air plenums and stratified zones in multiplexes. I've read through: http://www.iesve.com/downloads/help/The ... heHVAC.pdf on the multiplex,
but I'm still a bit unclear on some things.

In ApHVAC -> Edit Multiplex, are we suppose to assign all zones that refer to a room (occupied zone, stratified zone, return plenum)?
Image

If I do this, the multiplex now has 6 layers, where the stratified zones and return plenums are also considered principal rooms in layers 3-6.

As always,
Thanks.
Ben K
Mechanical Designer :shock:
macleodd
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Re: Plenums / Stratified Zones in Multiplexes

Post by macleodd »

That is wrong - you should be using three 2-layer multiplexes in the following airflow sequence:
Occupied (as Principal room), Stratified (blue), RA plenum (blue).

Library system 09i shows how this is laid out, but you can modify another system in the same way.

Regards
Donald
IES Development Staff
NebK22
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Re: Plenums / Stratified Zones in Multiplexes

Post by NebK22 »

Donald,

Thank you! I think these were my initial thoughts too, but someone had confused me along the way. Let me see if I understand correctly.

If I'm going with system 09i the process would be as follows:
1) Edit multiplex
2) Assign my 2 occupied spaces as principal rooms so that the multiplex has 2 layers.
Image

3) In the first layer of the multiplex, double click the stratified room (blue) and select the stratified space that matches the occupied space.
Image
4) While I'm still in the first layer, double click the RA plenum room (blue) and select the RA plenum space that matches the occupied space.

Is this correct? If so, is there an efficient way to match each stratified and RA plenum space to the principal room? When I double click the blue rooms in the system, it lists all spaces available in the project, even after assign from room groups.

As Always,
Thanks!
Ben
Ben K
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farahghanem
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Re: Plenums / Stratified Zones in Multiplexes

Post by farahghanem »

I believe that this is the correct way to do it, and as far as I know, there's no "quick" method. You have to assign the individual plenums/strat zones for each zone. I could be wrong about this tho.
Image
NebK22
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Re: Plenums / Stratified Zones in Multiplexes

Post by NebK22 »

Farahghanem,

It looks like my occupied space isn't being heated properly with the DV + radiant system. I've set up my geometry so that there is a hole between both the stratified space and the occupied space. In Apache HVAC, I've set the sensor location of the radiant panels (located in the stratified space) to the occupied space, but the occupied space isn't meeting the heating set point. Additionally, I have Macoflow checked when doing dynamic simulations.

Any idea what might be causing this?

Thanks!
Ben K
Mechanical Designer :shock:
farahghanem
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Re: Plenums / Stratified Zones in Multiplexes

Post by farahghanem »

Before looking at whether or not the set-up is the reason behind why you have unmet heating hours. Investigate that your system is working properly. That is the correct flow rates and temperatures are being supplied. There is a guide for unmet hours: http://www.iesve.com/support/faq/pdf/un ... -hours.pdf

Try looking at that first.

Also, from vista you can check through macroflo analysis that the air circulation between stratified and occupied zones is correct.
Image
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