Duct System Inspector

[nubrun.188780]

I have recently ventured into trying to implement using the system inspector, in order to determine teh pressure drop of the system. The problem is that it says that all of my components are set to preset or system, and that at least one needs to be set to calculated. The thing is that at least one component of each system is set to calculated.

For the VAV system, the air terminals are preset, the VAV outlet is set to calculated and the inlet is set to preset (All according to Kyle tutorial on his blog). Likewise for the air handler system, the outlet on the air handler is set to calculated.

So my question is what am I missing? According to the system inspector instructions things should be working. Any help would be greatly appreciated.

Thanks guys,
Nick

[Beancud]

I have recently ventured into trying to implement using the system inspector, in order to determine teh pressure drop of the system. The problem is that it says that all of my components are set to preset or system, and that at least one needs to be set to calculated. The thing is that at least one component of each system is set to calculated.

For the VAV system, the air terminals are preset, the VAV outlet is set to calculated and the inlet is set to preset (All according to Kyle tutorial on his blog). Likewise for the air handler system, the outlet on the air handler is set to calculated.

So my question is what am I missing? According to the system inspector instructions things should be working. Any help would be greatly appreciated.

Thanks guys,
Nick

Hi Nick, have you tried making VAV inlet to system/calculated?

Whats the error warning you get if you try to inspect? Have you checked duct connectivity? endcap, transition, are you using any custom kits?

[nubrun.188780]

Good morning Beancud,

I have not tried to change the inlet to system/calculated, becuase I was under the asumption that in order the duct and system to propagate information that the air terminals need to be preset, so that you can define the airflow to a space, and then from that point on the outlet of mechanical equipment attached should be calculated on the outlet side, so that it will calculate the flow reaching it, (for example if you have 3 air terminals, it would need to calculate the combined airflow), and then the inlet side should be preset so that it will take the calculated information and pass it on to the next piece of duct etc. Maybe I am wrong but that it how I understand it.

The actual error that I get is:
"Mechanical Supply Air 1: It is not possible to calculate the flow since all the components in this system have the flow configuration set to Preset or System. At least one component is required to have the flow configuration set to Calculated."

The duct connectivity seems to be good as it is propagating information all the way from the air terminals through the VAV box to the trunk. From my experience if there was a bad connection it will not propagate correctly.

Thank you for the ideas Beancud.

[cris8096]

Are you using the out of the box VAV??

I had issues with that as well, I went into the VAV Unit - Bypass Family and I "Remove Link" from the connector and it worked fine after that..

[mjdanowski]

Is the system "Well Connected?"

The inspect tool will not work if there is a physical disconnect and/or Revit feels like not showing it.

As you previously stated, all downstream equipment in a system (that which is being served) should be set to Preset. All upstream connections should be set to calculated (that which is serving).

The best way to look at it is the calculated connector will add up all the preset connectors under it. That calculated value can then be put into a preset connection and go upstream.

[nubrun.188780]

Are you using the out of the box VAV??

I had issues with that as well, I went into the VAV Unit - Bypass Family and I "Remove Link" from the connector and it worked fine after that..

I am using a VAV box that I created. I checked and there is no link between the connectors.

Is the system "Well Connected?"

The inspect tool will not work if there is a physical disconnect and/or Revit feels like not showing it.

There doesn't seem to be any disconnects in the system. But just out of curiosity how do you check for disconnects mjdanowski? Usually i assume that if information is passing the system is well connected? Is this a bad assumption?

One more thing to note is that we have a reheat coil on the VAV box. Now when i create a system from the air terminals to the Reheat coil the system inspector works. But I still have problems from the reheat coil to the Air handler. So I guess my question is does having a reheat coil effect the methodology used for setting up systems?

Thanks for the responses gentlemen,
Nick

[cris8096]

Can you uploaded your family to take a look at?

[nubrun.188780]

Can you uploaded your family to take a look at?

I attached the VAV box and the reheat coil. So for the system we have a standard "H" configuration, that goes to a VAV box and reheat coil.

Becuase of the reheat coil does the system need to be defined from the air terminals to the reheat coil? Or should the info pass through the reheat coil to the VAV box just fine?

[nubrun.188780]

UPDATE:
After I have tried some more things I have figured out that it is the Reheat Coil causing problems with the system. Although information still propagates through it into the VAV box, it causes problems with the system inspector. Removing the reheat coil allows teh low pressure system as well as the medium pressure systems to work.

So i guess my new question is, how are you guys getting the systems to work when you have reheat coil. I would like to have a system on the low pressure side, and then one on the medium/high pressure side. So any suggestions?

[cris8096]

Make a Vav Family with Reheat and a Vav Family without..