Refrigeration Piping

[SandShark]

Tomorrow, we finish piping in a new construction combination walk-in-cooler/freezer system. The evaporators for both systems are on a first floor and the condensing units are on a roof, approximately 8' above the evaporator coils.

The line sets penetrate through the top of each box where they 90 over and run horizontally for approximately 25' and 15', respectively. Once the lines penetrate the back wall of the building, they 90 over 3' and up 6' to the top ledge of an adjacent wall. Once over the wall, the lines will be 90'ed back down about a foot so they are parallel with the connections on each condensing unit. Then, it's just a matter of finishing the run horizontally to each condensing unit.

We have installed traps at each evaporator coil inside each box. My question is this. Considering the piping up over the roof and back down, will this situation cause any oil return problems and, if so, what can I do to alleviate this problem?

Thanks.

[frozensolid]

Trap the riser to the roof also. Once up top that little jog down will just act as invert, which will actually prevent oil from going back down the riser. With a six foot lift you may get by without the trap, but why take the chance.

[gerryboy00]

kinda inverted trap?
no problem with that.

[SandShark]

Thanks, guys. That answers my question.

[icemeister]

I agree with frozen on the need for a trap on the 6 ft riser. The up and over deal is in effect an inverted trap and is a good thing.

At the evaporators, are you elbowing down out of the evap, immediately trapping at the base of the riser and then up & out of the box? If so, good. I've seen a lot of jobs where the installer apparently read about the need for traps but didn't get the point that they're supposed to be located at the base of a riser and not in the middle of a horizontal run. :( (I'll have to get a pic of that for you)

Are you pitching the suction lines in the direction of flow, toward the compressor?

This is all quite contrary to TRANE's current thinking on refrigerant piping practice you know...........Do we care? ;)

[SandShark]

Originally posted by icemeister


At the evaporators, are you elbowing down out of the evap, immediately trapping at the base of the riser and then up & out of the box?[/B]

Yes, right off the factory suction line trapped and straight up out of the boxes.


Are you pitching the suction lines in the direction of flow, toward the compressor?[/B]Well, yes. Once the lines come up over the roof, it's probably going to be, at most, six feet to the furthest condensing unit.

[gbfromsd]

Don't forget to leave room on the suction pipe out of the coil for the TXV bulb. Seen alot 90'd right off the coil,
up and out of the lid. Only place left for the bulb is on
the vertical run.

[SandShark]

LOL - Thanks, I always remember to do that! Although, now that you've brought up the subject, the last Sporlan siminar I went to, the Sporlan rep's comment on the subject was "sometimes you gotta do what you gotta do." But, yes, as a matter of practice I've always allowed room for mounting the expansion valve bulb on the horizontal.