▲ 44 r/refrigeration
Rolling Stock HVAC
Train/Subway/Metro HVAC system
I know this ain't refrigeration but I thought I would share here as well in case anyone finds it interesting.
u/ApprehensiveStudy671 — 4 days ago
▲ 46 r/HVAC
Rolling Stock HVAC
Subway/Metro train HVAC system running on R134A.
u/ApprehensiveStudy671 — 4 days ago
▲ 29 r/HVAC
Using recovery machine for charging
Hi guys
Started a new job a few days ago working on rolling stock HVAC (subway/metro trains). The units run on R134a and they're dual-circuit systems with two Bitzer compressors, two evap coils, two condenser coils, and one big condenser fan. Total charge is around 20 kg (44 lbs), so about 10 kg (22 lbs) per circuit. Depending on the cooling demand, they'll run on one compressor or both.
What caught my attention is how they charge these things. After pulling a vacuum, they hook up a recovery machine and use it as a charging machine. It pumps liquid refrigerant straight from the bottle into the system, and the whole charge goes in pretty quick. Then they let it sit for about 40 minutes before starting it up.
I'm used to charging part of the refrigerant after the vacuum, then finishing the charge through the suction side with the system running. These guys just put the whole charge in at once with the recovery machine.
I asked the guy I was working with why they do it that way, and he said that's just the company's procedure and all the techs do it like that.
Even though the actual charging is fast, waiting 40 minutes for everything to settle kind of makes it a slow process overall. It was a warm day too, so low ambient temps weren't a factor. Charging through the suction side wouldn't have been an issue.
Has anyone else charged systems like this? Any pros or cons you can think of? Just curious if this is common anywhere else.
Thanks!
u/ApprehensiveStudy671 — 7 days ago
▲ 3 r/refrigeration
Using recovery machine for charging
Hi guys,
Started a new job a few days ago working on rolling stock HVAC (subway/metro trains). The units run on R134a and they're dual-circuit systems with two Bitzer compressors, two evap coils, two condenser coils, and one big condenser fan. Total charge is around 20 kg (44 lbs), so about 10 kg (22 lbs) per circuit. Depending on the cooling demand, they'll run on one compressor or both.
What caught my attention is how they charge these things. After pulling a vacuum, they hook up a recovery machine and use it as a charging machine. It pumps liquid refrigerant straight from the bottle into the system, and the whole charge goes in pretty quick. Then they let it sit for about 40 minutes before starting it up.
I'm used to charging part of the refrigerant after the vacuum, then finishing the charge through the suction side with the system running. These guys just put the whole charge in at once with the recovery machine.
I asked the guy I was working with why they do it that way, and he said that's just the company's procedure and all the techs do it like that.
Even though the actual charging is fast, waiting 40 minutes for everything to settle kind of makes it a slow process overall. It was a warm day too, so low ambient temps weren't a factor. Charging through the suction side wouldn't have been an issue.
Has anyone else charged systems like this? Any pros or cons you can think of? Just curious if this is common anywhere else.
Thanks!
Note: I'm aware this ain't refrigeration but I thought it still applies, in cause anyone here uses this method.
u/ApprehensiveStudy671 — 7 days ago
▲ 21 r/HVAC
Rolling Stock HVAC
Hey guys
​
Has anyone here worked on HVAC systems on trains?
​
I recently interviewed with one of the major train manufacturers here in Europe. The pay was definitely above average and they offered some pretty decent perks too. There was a technical interview, and I answered everything as best I could. They wanted to make sure I understood things like superheat, subcooling, and a bunch of other refrigeration fundamentals. I got the impression they were interviewing quite a few candidates. The position was for a technician role at their factory/production line.I never heard back from them though.
​
But just a few days back, I interviewed with another company for a similar role, but this time the work would be directly on them trains themselves. They have several depots where the subway/underground trains are serviced, repaired, and maintained.
​
The schedule is rotating shifts, but only every three months. It used to rotate weekly, which is actually why I turned down a possible offer from another company last year. Switching every three months is something I can live with. Basically, three months on early mornings, then three months on afternoons, followed by three months on nights.
​
The thing is, the salary they're offering is higher than anything else I've been offered so far, plus they have some good perks and I kinda like working at large depots and industrial shops instead of driving from one location to another for service and maintenance calls. I did trucks refrigeration as well as reefers for a while and I liked the layout of the place, heavy duty stuff and machinery.
​
Last year I spoke with a technician who had done this exact job on trains and eventually quit. He said it was stressful and burned him out, especially the night shifts. That said, I think when he was there the shift rotation was weekly. He also had a wife and kids, I don't. He mentioned that overtime was pretty common because when a train HVAC system goes down or the systems act up, it has to be fixed no matter what.
​
During the interview they told me that most of their HVAC systems run on R407C.
​
Recently I asked on here about precision cooling and HVAC work in data centers. The position I was offered there turned out to be more of a glorified maintenance job than a true HVAC-R technician role. Needless to say I lasted two days.
​
I've been doing some research on train HVAC systems, and from what I've seen they're mostly rooftop units running special scroll compressors. It also looks like many of them operate as heat pumps, providing both cooling and heating.
​
I've gathered a few photos for reference. They're from different manufacturers, but they give a good idea of what these units look like.
​
Anyway, I was just curious if anyone here has worked on similar systems and what your experience was like.
​
Thanks!
​
​
u/ApprehensiveStudy671 — 21 days ago
▲ 1 r/hamburgers
Does it qualify?
Does a hamburger with no bread qualify as such? Some folks like myself avoid bread (and other carbs) for the most part. I came to love hamburgers with no bread.
This is beef , gouda cheese, thin slice of tomato and pickles that ain't visible (hidden under the cheese) and a sunny side up. Salt and pepper (Himalayan salt)
No bread, no fries....
I love it this way !
u/ApprehensiveStudy671 — 28 days ago
▲ 1 r/refrigeration
Data Center HVAC-R roles
Hey guys
I’m curious if anyone here has moved from regular HVAC/refrigeration work into data center maintenance roles.
I’m not talking about working directly for OEMs on the really high-level critical cooling systems, but more the HVAC tech side of data center operations/facilities maintenance.
From what I understand, techs with HVAC backgrounds end up doing a mix of cooling, mechanical, monitoring systems, troubleshooting, maybe some electrical/basic facilities stuff, BMS.....
They seem to be hiring mainly electricians as well as HVAC techs and I know it involves rotating shifts.
Is it a good long term path?
If you get hired, can you eventually specialize in critical cooling or move into OEM work later on? Or even any other specialization within HVAC-R at other kind of critical facilities?
I’m especially interested in hearing from HVACR guys who switched over and whether you felt it was worth it. Or maybe you work for a manufacturer and visit data centers? I mean, data centers are just expanding.
Thanks!
u/ApprehensiveStudy671 — 1 month ago
▲ 7 r/datacenter
Data Center HVAC roles
Hey guys
I’m curious if anyone here has moved from regular HVAC/refrigeration work into data center maintenance roles.
I’m not talking about working directly for OEMs on the really high-level critical cooling systems, but more the HVAC tech side of data center operations/facilities maintenance.
From what I understand, techs with HVAC backgrounds end up doing a mix of cooling, mechanical, monitoring systems, troubleshooting, maybe some electrical/basic facilities stuff, BMS.....
They seem to be hiring mainly electricians as well as HVAC techs and I know it involves rotating shifts.
Is it a good long term path?
If you get hired, can you eventually specialize in critical cooling or move into OEM work later on? Or even any other specialization within HVAC-R at other kind of critical facilities?
I’m especially interested in hearing from HVAC guys who switched over and whether you felt it was worth it. Or maybe you work for a manufacturer and visit data centers? I mean, data centers are just expanding.
Thanks!
u/ApprehensiveStudy671 — 1 month ago
▲ 19 r/HVAC
Data Center HVAC roles
Hey guys
I’m curious if anyone here has moved from regular HVAC/refrigeration work into data center maintenance roles.
I’m not talking about working directly for OEMs on the really high-level critical cooling systems, but more the HVAC tech side of data center operations/facilities maintenance.
From what I understand, techs with HVAC backgrounds end up doing a mix of cooling, mechanical, monitoring systems, troubleshooting, maybe some electrical/basic facilities stuff, BMS.....
They seem to be hiring mainly electricians as well as HVAC techs and I know it involves rotating shifts.
Is it a good long term path?
If you get hired, can you eventually specialize in critical cooling or move into OEM work later on? Or even any other specialization within HVAC-R at other kind of critical facilities?
I’m especially interested in hearing from HVAC guys who switched over and whether you felt it was worth it. Or maybe you work for a manufacturer and visit data centers? I mean, data centers are just expanding.
Thanks!
u/ApprehensiveStudy671 — 1 month ago