Need an Explanation

[rude]

Hi Guys i came across a package unit the other day, with an additional coil in the return air duct. Apparently gas from the refrigeration system went through this coil.

Pics
http://i35.photobucket.com/albums/d193/123MMM/Image007.jpg

http://i35.photobucket.com/albums/d193/123MMM/Image033-1.jpg

http://i35.photobucket.com/albums/d193/123MMM/Image036.jpg

Now i thought maby its use was for heating? for energy saving perhaps. But the package unit has reverse valves and the control system is very basic so i doubt there would of been some solenoid that energises at a certain temp, but i could be wrong.

Any ideas?

[Brian_UK]

There don't seem to be any condensate drainage coming from that coil so perhaps it was a heating only addition.

Also, was it connected to a completely different system?

It's fun when you get to a new site isn't it ;)

[rude]

Well the unit conditions a supermarket so id say heating would be used most due to the cooling of the fridges spilling into the shop.

My company did a retro fit and removed all the old refrigeration gear but i wasn't there when they removed it. So apparently that coil was attached to one of the condensing units. We replaced everything with a rack system so they just removed all the old gear.

I got no idea how it would of controlled temp. I just thought someone may have seen this done before or knew a reason as to why someone would do this. ONly thing i can think of is maby an energy saving thing for heating maby? But the store owner had a switch for the a/c in his office to turn it on and off so if the fan was off the condensing unit would trip on HP i guess? ahh well unit needs a lot of work should keep me busy for a while.

[modvalve]

looks like a reheat coil for something probably winter time to heat up the return air to save power and keep the A/C unit from starting up on heating