Discharge or Supply air?

[Under_Control]

Just one for discussion, while trying to create a conventional naming system, the question has arrisen. With a straight cool unit would you call the air in the duct after the cooling coil "supply air" or "discharge air"? Would you differentiate based on sensor location (like temp right off the coil vs temp further up the duct) if you only had 1 sensor? Now both sensors. Now add a duct heater, and name the sensors before and after the heater. How about F&B units? Might call the sensor after the bypass "mixed" and the other "cooling coil", but how many different locations can you think of and what would you call them and why?

[roverXE]

We usually use PREHEAT, REHEAT, COOLING COIL, (DE)HUMIDIFICATION TEMPS etc if there are multiple temps on a unit. If there is only one temp we call SUPPLY TEMP (or discharge temp, user preference)

[SuperDuperTech]

We had a great teacher at the Johnson Controls Instititute that told us that these namings should be point of reference referenced. A air handlering units discharge temp is a vav box supplies air temp.

[Under_Control]

That part makes sense, some apps have a standard name for some points, but when you are renaming points from DCSs, UNTs VMAs and point multiplexers, sometimes the naming gets a bit crazy. one of my customers says "air from the grill is supply air because it supplys the room" and another says it is discharge from the grill and supplied from the unit. We usually use the discharge from the unit and supply if the sensor is after a heat strip, but some customers want what they want no matter the logic. Just a query to see how everyone else decides on naming. thanks for the feedback so far.

[tlp261]

By that JCI logic, it should be VAV inlet temp.

[Under_Control]

Where does that come from? The VMA and VAV controllers (single duct)will label a supply air sensor "Box Supply Temp", and (dual duct) Dis Air Temp, so I guess Im not sure where that label comes from.

[scrooloose]

We always use discharge air for outlet of vav and source air temp for inlet.

For AHU/RTU i have always seen supply air temp. Then use pre/post coil for temps in between.

[azzad]

How about leaving and entering.

[osiyo]

Just one for discussion, while trying to create a conventional naming system, the question has arrisen. With a straight cool unit would you call the air in the duct after the cooling coil "supply air" or "discharge air"? Would you differentiate based on sensor location (like temp right off the coil vs temp further up the duct) if you only had 1 sensor? Now both sensors. Now add a duct heater, and name the sensors before and after the heater. How about F&B units? Might call the sensor after the bypass "mixed" and the other "cooling coil", but how many different locations can you think of and what would you call them and why?

Well, the main thing is that we make every reasonable attempt to avoid ambiguity, and to be consistent.

In general, if some process is performed, or can be, by whatever equipment upon the media (air or water) to change its properties; then the final outlet temperature (or whatever) of said equipment would be referred to as "Discharge ...".

If its a mixing situation, but downstream within the same equipment further changes can be made to the air or water stream then a temp probe within the mixing area would be called "Mixed".

We try to be specific.

In some cases, with some equipment configurations, we find that using terms like "Entering ..." and "Leaving..." are the better choice. For instance, on a recent job I was working with an AHU which had a preheat coil. There is an averaging temp sensor directly after the coil. And it is labeled Preheat Coil Leaving Temp. So as to be specific, since there are several other coils and temperature probes in the unit.

In the case of VAV's, on each VAV graphic screen the temp probe in the final discharge air stream is called a DAT. Now, on each such screen we also typically show the associated air handler's DAT, and label it that way. i.e. AHU #2 DAT. As versus labeling it "Supply Air Temp". Since, if we don't actually have a temp probe in the duct just before the VAV, we don't actually ... really ... know what the air temp is at that point.

I've seen numerous cases where an air stream has picked up considerable heat between the point where it left the air handler and arrived at a VAV.

To further be clear, we take pains to ensure that on both our drawings and on our graphic screens the precise arrangement of equipment components and placement of sensors is accurate and reflects reality.

And if a particular sensor is called something in one place, its referred to by that exact same name anywhere else it's value appears. Both on additional graphic screens, and on our drawings.

As concerns customer preferences, what can I say? Its their equipment and their front end. If they want something named whatever despite our best efforts to persuade them otherwise, we re-name it to whatever they want.

[clmair2fly]

how about "Goesinta" and "Goesouta" :D

[gnomethang]

how about "Goesinta" and "Goesouta" :D

Bless you!

[incontrol]

My boss is misogynistic so we call it Supply not Discharge. Sounds like puss or blood.