I've recently powered an industrial chiller for a friend/client and have subsequently been presented with a puzzle. Due to the out of the way location, his go-to HVAC tech doesn't want to make the trip in person. He's also avoided answering a direct question multiple times and while he was helpful in the beginning, I will not ask the same question of him again. I simply don't know him well enough to badger him as I would have with my go-to guy (RIP pg).
The unit fires up perfectly and cools the attached equipment as expected but after running, it will not restart until 24-48 hours has passed. Most of you are probably thinking it's the start capacitor... we'll get to that shortly.
In sequence, the circulation pump starts, the condensor fans roar to life, the comp contactor switches on, a low hum ensues and the internal breaker flips after several seconds. We've coordinated over the phone and I've verified that the compressor windings meter out correctly (0R4, 0R8 and 1R2), none go to ground, the high/low guage pressures (270 psig/50psig) met his approval, the compressor external temp is well within normal range (150F after running for 2+ hours), the 65uF run capacitor test to 67uF. The start cap? There is NO start cap despite the Panasonic literature stating that the starting method is CSR and the label affixed to the comp list a RUN cap value of 60uF and a STR cap value of 100-140uF. When I ask about adding a hard-start kit, the tech said "sure, why not, it can't hurt but I'm not convinced that that's the problem". Further inquiries as to what he thinks MAY be the problem have gone unanswered.
I'm adding the 5-2-1 hard-start kit on Monday so we'll see, but I'd love to have more insight from someone in the know.
The comp in question is a Panasonic C-SBP170H16Y 5hp scroll compressor. While in operation, the chiller draws a steady 24A (240V) with no appreciable dips or spikes. I'm also carrying a breakout box to split the incoming power into 2 120 V circuits so that I can test L1 and L2 independently with my load tester (Extech ct70).
If youve gotten tgis far, thank you for taking the time. Any thoughts on the matter?
The unit fires up perfectly and cools the attached equipment as expected but after running, it will not restart until 24-48 hours has passed. Most of you are probably thinking it's the start capacitor... we'll get to that shortly.
In sequence, the circulation pump starts, the condensor fans roar to life, the comp contactor switches on, a low hum ensues and the internal breaker flips after several seconds. We've coordinated over the phone and I've verified that the compressor windings meter out correctly (0R4, 0R8 and 1R2), none go to ground, the high/low guage pressures (270 psig/50psig) met his approval, the compressor external temp is well within normal range (150F after running for 2+ hours), the 65uF run capacitor test to 67uF. The start cap? There is NO start cap despite the Panasonic literature stating that the starting method is CSR and the label affixed to the comp list a RUN cap value of 60uF and a STR cap value of 100-140uF. When I ask about adding a hard-start kit, the tech said "sure, why not, it can't hurt but I'm not convinced that that's the problem". Further inquiries as to what he thinks MAY be the problem have gone unanswered.
I'm adding the 5-2-1 hard-start kit on Monday so we'll see, but I'd love to have more insight from someone in the know.
The comp in question is a Panasonic C-SBP170H16Y 5hp scroll compressor. While in operation, the chiller draws a steady 24A (240V) with no appreciable dips or spikes. I'm also carrying a breakout box to split the incoming power into 2 120 V circuits so that I can test L1 and L2 independently with my load tester (Extech ct70).
If youve gotten tgis far, thank you for taking the time. Any thoughts on the matter?
Could be it needs the start kit. I had the reverse problem with my up AC. A long off period pooled the oil in the compressor and then during the start, the board detected something not sure what, and would shutoff. A restart 5 minutes later would go ok, probably because a little oil got sloshed after the first failed start. I will say this, the first restart after being off for more than 24 hours sounds painful after they added the restart. One other possibility might be a weirdness in the TXV. I am thinking the pressure bleeds off too slow on the liquid line and so on restart pressure is too high for the compressor to start. If the pressure gauges are builtin, if the pressure difference after 24 hours reduced significantly, that might be a clue.
@mikeAtx
Thank you sir. Excessive pressure was the niggling thought that I haven't been able to shake and the possibility was unadressed by the pro.
The time it takes before a successful restart will occur is obviously far in excess of any thermal reset or heat issue so it sounds quite reasonable to me.
Even if the start kit works I'll note my concerns in that regard to the client. The body of the TXV was lightly frosted over after extended operation but I gather that isn't abnormal in and of itself. The room was warm and humid.
I've never wanted to add refrigeration troubleshooting and repair to my skill set but asking me to walk away from a puzzle is like calling Marty McFly chicken... a fatal flaw
Thank you sir. Excessive pressure was the niggling thought that I haven't been able to shake and the possibility was unadressed by the pro.
The time it takes before a successful restart will occur is obviously far in excess of any thermal reset or heat issue so it sounds quite reasonable to me.
Even if the start kit works I'll note my concerns in that regard to the client. The body of the TXV was lightly frosted over after extended operation but I gather that isn't abnormal in and of itself. The room was warm and humid.
I've never wanted to add refrigeration troubleshooting and repair to my skill set but asking me to walk away from a puzzle is like calling Marty McFly chicken... a fatal flaw
I can't think of anything except pressure tbh. My AC's are 2 stage with the solenoid to bypass some of the flow so those equalize quickly. I'm not familiar with chillers. The only other thing I note is 24A seems high for a AC, but may be completely normal for a chiller. Another thing that will dramatically change comp current is the condenser coil temp. A 100 degree day on mine might pull 8A while at 75 it is more like 5. The comp has to work harder on a hot day and it shows. In my case what has driven me down this path is AC condenser fan failures that cause a comp to overheat. Very bad for them. In my previous unit, I put current sensors on both the comp and fan and would monitor to make sure everything was good. Any deviation from norm caused a shutdown. My understanding is comp overheat is the kiss of death. Modern refrigerants turn acidic when overheated. My latest is a carrier with an ECM fan, which also failed, and uses 485 smart comms. After that fan failed I decided to reverse engineer the protocol and just finally replaced their board with mine. Mine monitors way more than theirs did. I may be a bit OCD...
The unit is a little more in line with your modified AC control than a standard AC and also has a circulation pump to handle the coolant. It features seperate current transformers for the compressor, condensor fans (2), circulation pump but tbh, I've relied on my amp clamp rather than the control display while troubleshooting. It has never shown an overcurrent or temp fault and the draw breaks down to ~16A for the 5hp comp, ~3.7A for the pump and ~3.2A for the 2 fans. Add a little for the control system and 24A looks reasonable. 24A is also the maximum continuous draw for the rated 30A breaker. I'm now wishing I'd have paid close attention to the pressure gauge readings prior to a failed vs successful start up 🤦♂️
Live and learn I guess. I will cycle the system and take note before adding the cap and relay on Monday
Live and learn I guess. I will cycle the system and take note before adding the cap and relay on Monday
The hard-start kit did the trick and the installation couldn't have been much easier. The Blind Hog is up two acorns today. Cheers
Very good. Did you notice, did the pressure difference fall significantly after 24 hours. For residential, restarts are delayed 5 minutes typically for pressure redux. If you do alot of hvac I stumbled on a site a few years ago hvac-talk dot com that is pretty good. I think you may fall into their pro category.
I did pay more attention to the pressure guages this time. The high/low sides were equal on arrival (unit hadn't run in a few days) and it started normally. After running for 45 minutes or so, I powered it down, waited 15 min. The restart failed with the high side pressure at approximately 2x that of the low side. In went the kit and bingo...
I run across situations that overlap with HVAC or refrigeration pretty infrequently but this is twice in 6 months. Maybe I should learn a bit more... thank you for the forum suggestion. I have found good info there and could bluff my way through I suppose (my lic does cover hvac/reefer elec), but they're pretty quick to escort non-pros off the property 😂
I run across situations that overlap with HVAC or refrigeration pretty infrequently but this is twice in 6 months. Maybe I should learn a bit more... thank you for the forum suggestion. I have found good info there and could bluff my way through I suppose (my lic does cover hvac/reefer elec), but they're pretty quick to escort non-pros off the property 😂