HVAC/R and Air Conditioning - Why survive SHTF if it gets hot

[Pretend To Imagine]

Don’t underestimate carbon tracing when diagnosing a short circuit fault.

Initially I found a bad electric heater that was causing a 400 amp 3 pole breaker to trip. I removed the fuses for the heater and it would still intermittently trip the breaker with increasing frequency. Even with the fuses removed there is a path between the terminals due to carbon from a previous arc flash. Once I disconnected the wiring from the terminals the breaker didn’t trip and the unit ran normally.

 

[Pretend To Imagine]

1999 Trane chiller with 100 ton screw compressors. Wye Delta motor starter. Impressive that this thing still runs.

 

[harmacist]

1999 Trane chiller with 100 ton screw compressors. Wye Delta motor starter. Impressive that this thing still runs.

i have spent quite a few freezing winter nights on waterfront rooftops trying to get tranes to fire back up. its nice to see another guy here who is actually in the field, although you work on slightly larger equipment than i do. i love working on the old rather than the new thats for sure. i have had nothing but bad luck with modern trane equipment. bad boards out of the box, going behind trane factory service because they fucked up a warranty repair on some of their watercooled samsung partnered garbage. we actually had a watercooled 40 ton that we had to take apart and reassemble on site because it had to land on a mezzanine and there was no other way to get it up there. when it came time to fire it up nothing would operate. trane startup guys figured out it was sabotaged from the factory. the worker also wrote "FUCK TRANE" underneath one of the insulation panels in the blower section.

 

[Pretend To Imagine]

i have spent quite a few freezing winter nights on waterfront rooftops trying to get tranes to fire back up. its nice to see another guy here who is actually in the field, although you work on slightly larger equipment than i do. i love working on the old rather than the new thats for sure. i have had nothing but bad luck with modern trane equipment. bad boards out of the box, going behind trane factory service because they fucked up a warranty repair on some of their watercooled samsung partnered garbage. we actually had a watercooled 40 ton that we had to take apart and reassemble on site because it had to land on a mezzanine and there was no other way to get it up there. when it came time to fire it up nothing would operate. trane startup guys figured out it was sabotaged from the factory. the worker also wrote "FUCK TRANE" underneath one of the insulation panels in the blower section.

I installed a 10 ton Trane split unit the other day at the request of a customer. Unit has 6 circuit boards and a VFD for the blower. You have to run 4 separate cables from the indoor unit to the outdoor unit, and 2 of them have to be shielded for communication. You have to download an app and connect to the unit via Bluetooth to startup or troubleshoot it.

As far as equipment size, I’ve worked on units up to a couple thousand tons, but I don’t have any accounts with anything that big currently. I’ve also done market refrigeration.

 

[Dawdler]

Don’t underestimate carbon tracing when diagnosing a short circuit fault.

Initially I found a bad electric heater that was causing a 400 amp 3 pole breaker to trip. I removed the fuses for the heater and it would still intermittently trip the breaker with increasing frequency. Even with the fuses removed there is a path between the terminals due to carbon from a previous arc flash. Once I disconnected the wiring from the terminals the breaker didn’t trip and the unit ran normally.

It looks like water was dripping on fuse block. There's also sparking when you touch the contact. Flashover will destroy the short for a while, then it would start heating up and carbonizing further.

1999 Trane chiller with 100 ton screw compressors. Wye Delta motor starter. Impressive that this thing still runs.

Nothing to go bad as long as filters and screens are replaced on interval. Wear on screw is so low it's practically neglegible. Once it is started there's no wear, just on startups due to high current surge that will break rotor cage and low lubrication.
Bearings are probably oil suspended also.

 

[Pretend To Imagine]

It looks like water was dripping on fuse block. There's also sparking when you touch the contact. Flashover will destroy the short for a while, then it would start heating up and carbonizing further.


Nothing to go bad as long as filters and screens are replaced on interval. Wear on screw is so low it's practically neglegible. Once it is started there's no wear, just on startups due to high current surge that will break rotor cage and low lubrication.
Bearings are probably oil suspended also.

The sparking is me hitting it with 1000vdc from my megger

 

[FieldPiece]

Figured I'd ask here just to be sure. Family members AC went out and he asked me to check on it. Intermittently stopped and started working then stopped entirely. I figured it's the contactor since he recently replaced the capacitor. Contactors getting cooling call. Voltage coming into the contactor but not coming out. There is continuity on one side of the contactor but not on the other. That's a bad contactor for sure right?

 

[Pretend To Imagine]

Figured I'd ask here just to be sure. Family members AC went out and he asked me to check on it. Intermittently stopped and started working then stopped entirely. I figured it's the contactor since he recently replaced the capacitor. Contactors getting cooling call. Voltage coming into the contactor but not coming out. There is continuity on one side of the contactor but not on the other. That's a bad contactor for sure right?

Did you take the cover off and look at the contacts? It sounds like a bad contactor from what you described. It’s staying pulled in the whole time?

 

[Oxyjen]

Did you take the cover off and look at the contacts? It sounds like a bad contactor from what you described. It’s staying pulled in the whole time?

In certain states, 99% of the time this is caused by a bug taking up residence in the contactor, preventing it from closing all the way.

 

[FieldPiece]

Did you take the cover off and look at the contacts? It sounds like a bad contactor from what you described. It’s staying pulled in the whole time?

The plunger wasn't actually visible on it but it did have voltage on one side just not the other.

 

[Pretend To Imagine]

The plunger wasn't actually visible on it but it did have voltage on one side just not the other.

It was staying pulled in the whole time?

Edit: Did you have 24v on the coil as measured from one side to the other? (Not referencing ground when taking measurements)

 

[FieldPiece]

It was staying pulled in the whole time?

Edit: Did you have 24v on the coil as measured from one side to the other? (Not referencing ground when taking measurements)

Yeah it was receiving a cooling call. It wasn't chattering or anything.

 

[Cat Hyde Boots]

Thread reminding me why I don't do residential.

 

[Pretend To Imagine]

Thread reminding me why I don't do residential.

View attachment 6476105

Ammonia?

I’ve not messed with ammonia, but have worked on C02 systems for grocery refrigeration. The equipment is cool, but the customers are demanding, and I don’t miss the on call.

 

[Cat Hyde Boots]

Ammonia?

I’ve not messed with ammonia, but have worked on C02 systems for grocery refrigeration. The equipment is cool, but the customers are demanding, and I don’t miss the on call.

Yes. At the company I work at, I'm rarely scheduled for local service so I actually have time off. 4 days off, as a matter of fact. The trade off is I spend a lot of time in hotels and I'm on 10 days while working.

Most ammonia techs are more local which means being on call more, but your likelihood of actually being called in isn't as guaranteed as in commercial.

 

[Pretend To Imagine]

The stupidity of people never ceases to amaze me. Another company sent a tech who set the thermostat on fire when they tried to replace a contactor and put high voltage onto the low voltage circuit.

 

[FieldPiece]

The stupidity of people never ceases to amaze me. Another company sent a tech who set the thermostat on fire when they tried to replace a contactor and put high voltage onto the low voltage circuit.

Jesus, the wires are different sizes, how do you do that short of being a massive retard? If we're talking about funny fuck ups. We recently hanged about 40 feet of double wall pipe that was about 3 feet in diameter in a gymnasium. For some reason it was suspended just using basic cable with no belly bands. It was doglegged for some reason right off the drop so for some reason an idiot decided to cut the cable thinking it would fix it. 40 feet of double walled pipe crashing to the earth from about 30 feet up like goddamn twin towers. Probably like 5-8k gone in an instant.

 

[Pretend To Imagine]

Jesus, the wires are different sizes, how do you do that short of being a massive retard? If we're talking about funny fuck ups. We recently hanged about 40 feet of double wall pipe that was about 3 feet in diameter in a gymnasium. For some reason it was suspended just using basic cable with no belly bands. It was doglegged for some reason right off the drop so for some reason an idiot decided to cut the cable thinking it would fix it. 40 feet of double walled pipe crashing to the earth from about 30 feet up like goddamn twin towers. Probably like 5-8k gone in an instant.

Wow that’s retarded! I’ve had someone cut one hangar on a run like that but it didn’t fall, just really made it sag. It was a framer and he cut the hangar because it was near his wall even though it wasn’t actually in his way.

 

[Cat Hyde Boots]

The stupidity of people never ceases to amaze me. Another company sent a tech who set the thermostat on fire when they tried to replace a contactor and put high voltage onto the low voltage circuit.

I was at this large supermarket build and one of the illegal construction workers decided it was a good idea to steal some copper. He cut open a refrigerant line and managed to dump a couple thousand lbs of refrigerant into the building. Hazmats were there for days cleaning up. Pretty sure the EPA got the alien sent to federal too.

 

[Pretend To Imagine]

I was at this large supermarket build and one of the illegal construction workers decided it was a good idea to steal some copper. He cut open a refrigerant line and managed to dump a couple thousand lbs of refrigerant into the building. Hazmats were there for days cleaning up. Pretty sure the EPA got the alien sent to federal too.

That’s almost as funny as when people try to steal live electrical equipment.