Piping up hill? ADVISE PLEASE.

[icefield]

4 ton condensing unit about 111 feet from dx coil in Make up air unit situated in basement (parkade).
Piping has to go 8' vertical up from TXV, 10' Horizontal, 8' down wall, then into 6" PVC chase below grade, then 75' at slight grade (angle unkown, but I have been told not too steep - like maybe 6" over 75'??) up hill towards condensing unit, up about 5' at 45 degrees to grade level, then about 5' horizontal into cond unit (6 - 90 degree elbows, and solenoid valve). I'm pretty sure this compressor will run out of oil pretty quick. How can this be properly piped to allow oil return?
Thanks in advance. Oh yah, I have had nothing to do with this job until the piping needed to be done!

[Gib's Son]

Seriously, call the mfr, send them a sketch and ask THEM to size the lines for you. I would not want to take responsibility for something like that....I'd want the mfr. to lean on in case of problems.

Also, be careful of the direction you install the solenoid valve. I got called out to a job that had some crazy line sets and they were having problems with pressures. The installing contractor and Carrier could not figure out what was wrong and they were about to tear out all the lines and start again. An old timer like me likes to "feel" whats going on in a system and when I checked the solenoid valve you feel that is was acting as a meeting device and flashing the gas. The installation instructions told them to install in backwards, which is what they did. As soon as they reversed the valve the problems went away. Lesson here is....install the valve in the direction of flow even if the literature says otherwise.

[heatingman]

Chances are, that this system may be a 410 system w/ poe oil. If so, poe oil flows much better with gas than did mineral oil. Also, velocity is the key here. Don't get too fancy with pipe size re- engineering. I drew it out, and it looks to me that the piping esentially makes a large inverted trap leaving the evap, and then underground on the way to the condenser, theres a incline and that forms a very long trap. From what you've explaned, the overall elevation differance sounds minimal. Check the install manual, who's the oem?

[emmettair]

As Gibs son said contact mfr. to be positive. Pipe size determined by system/mfr. Velocity is key, you may have to go to smaller than normal pipe size(length of run,90s,etc.) You'll have to add traps on your risers, to bring the oil back in "stages". You mentioned possibly the 75' horizontal run was pitched away from compressor-it needs to be pitched towards compressor at proper pitch(atleast suction line). Definitly an suction accumalater and possibly an oil seperator. Solenoids, not sure with equip. you got if you would make it a pumpdown or just an isolation. Crankcase heaters. You will probably have to add oil for length of run and traps. Maybe above info will help. Again, i would consult someone or do some serious homework before starting the project. Good Luck!

[icefield]

Thank you for the input so far.
Carrier M/N: 24ABR348A320
I was thinking pump down due to length of pipe. Limited experience with long piping, especially with incorrect pitch.
I will be sure to contact Carrier for recommendations before doing anything, but I do value all the information.

[Mstrav]

call carrier and get the long line-set application guide!!!!! if it is single phase it needs a hard start, you also want head preasure control, crank case heater, everything that is provided with low ambient kit and very critical to size the lines right and calc in all the 90's and 45's. carrier will help you decide so that you have no warranty issue.

matt

[second opinion]

What is your actual virtical seperation from the air handler in the parking garage and the condenser on the hill side? What are you going to use the solenoid for? If I am interpreting your measurements, it looks as if you would have one story or approximately 10 feet virtical seperation. When you call Carrier you will need accurate measurements.

I just ran it through a piping program with my scenario and came up with 7/8 3/8 No solenoid valve and no traps. Post your results after you speak with Carrier I would be curious to see.

[keepyoucool2003]

that's one for my piping design/calc book, too much math. How about a water cooled condenser, it would take them years to dump as much water down the drain as that's going to cost to pipe/install. Just wondering... makeup air unit... where is the makeup air getting it's air from that a condenser can't sit next to it outside/hang off the building? Its one of those things I just would laugh to see. Lemme know I'm dying to hear!!!

:confused:

[Parameter]

4 ton condensing unit about 111 feet from dx coil in Make up air unit situated in basement (parkade).
Piping has to go 8' vertical up from TXV, 10' Horizontal, 8' down wall, then into 6" PVC chase below grade, then 75' at slight grade (angle unkown, but I have been told not too steep - like maybe 6" over 75'??) up hill towards condensing unit, up about 5' at 45 degrees to grade level, then about 5' horizontal into cond unit (6 - 90 degree elbows, and solenoid valve). I'm pretty sure this compressor will run out of oil pretty quick. How can this be properly piped to allow oil return?
Thanks in advance. Oh yah, I have had nothing to do with this job until the piping needed to be done!
:)
Make sure you put a sight glass just before the txv, it will aide in getting the correct charge.
God luck on the rest.