Return Line on AHU - Purpose? 1

[Roktgr]

Hello,

I had a question from my HVAC mechanic in regards to the plumbing on 5 of our air handler units. I am not very experienced with HVAC systems yet and from what I can tell the line in question serves no purpose.

The line in question is the one that bypasses the coil and would allow condensate to be fed back into the steam line.

Can anyone shed some light on the purpose of routing such a line back to the main steam line or if it can be removed and capped off.

Thank you.

 

[MintJulep]

It allows condensate to flood back into the coil on shut-down when the remaining steam in the coil condenses and begins to draw a vacuum.

 

[ione]

Why not use a vacuum breaker?

 

[KiwiMace]

A vacuum breaker is often also used to protect the coil in the same manner.

This is an example of what happens if you don't have this protection...

http://www.youtube.com/watch?v=Zz95_VvTxZM

 

[Roktgr]

Ah, makes sense. Hadn't considered that. Thanks!

 

[willard3]

This assumes that the condensate line is open to atmosphere.