IT'S JUST AN EXHAUST FAN HOW HARD CAN IT BE??
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- čas přidán 27. 07. 2024
- This was an intermittent exhaust fan call that turned out to be epic, it's always the most difficult calls that turn out to be the best learning experiences...
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00:00 TEASER
00:27 SPONSOR CARD
01:28 INITIAL INSPECTION
02:32 PAY ATTENTION TO YOUR SURROUNDINGS
03:48 ALWAYS TURN AWAY
08:03 DISHFAN INSPECTION
10:21 WE ARE BACK
11:10 EARLY MORNING MOTOR INSPECTION
13:03 MUA MOTOR INSULATION TEST
14:26 WTF MOMENT
15:58 I'M BACK AGAIN
18:47 MOTOR STARTER VERIFICATION
19:16 BACK AGAIN
21:00 BURNT WIRES
23:27 WTF MOMENT #2
28:20 CLOSING WORDS
"Really Interesting" = secret code for WTF
"what dumbass installed this"
Really...I thought it meant What Brain-Dead-Fucking-Moron do I want to Shoot several times in the balls with a 12-Guage loaded with table salt?
😄😁😆😅😂🤣
P.S.: A Table Salt shell acts a lot like a bird shot shell in that it doesn't do a lot of damage to a person, but because it's salt, it HURTS LIKE HELL!!!
A friend of mine tried it one year when hunting (he loads his own shells - NEVER break into his house, he has several Sadistic shell loads he's come up with for defense) and one of the other hunter's tripped and accidentally shot my friend in the ass with one (far enough away to avoid serious injury, by the way he tells it, he's rather get stung by a dozen yellow jackets than take a table salt shell in the ass again)...they never did find out if a table salt shell would work like a bird shot shell, too bad, that would be a great way to pre-season your dinner as you kill it...
@@HappilyHomicidalHooligan 🤣 preseason your dinner got me
Just like: Electrician X.
@@HappilyHomicidalHooligan thanks
One diagnostic tool that sometimes helps narrow things down is the temperature of wire connections. I use a cheap point and shoot thermometer, but you have that awesome thermal camera. A quick look through that might show up any extremely high temperatures on motor bearings, contactors, wire connections, etc. I doubt it would have solved this mystery faster, but it may have helped rule some things out. 🤷♂️
That is so true. I do not work in the AC industry at all (but admire the troubleshooting skills of our protagonist), I do datacenter stuff for a living but proper equipment cooling is also key there. What I can really recommend are the smartphone attachments from Flir. Size of a matchbox they turn your smartphone into a great thermal camera. In my case I find overheating power supplies of servers as they have trouble getting rid of hot air as some other numb nut has a pack of wires running in front of the air outlet or even appliances that are installed the wrong way and instead of sucking in freezing air from the cold aisle side they "pollute it" by blowing their own hot air back into it. In your case you can spot contactors running hot due to bad internal resistance, motor bearings running hot or motor windings. Channel owner has those tools in place, always surprised how you can sense refrigerant levels with them :)
I've been in the facility maintenance arena for over 30-years, and you have some of the best troubleshooting skills I've ever seen. Plus you do a great job of explaining the practical aspects of how things work, and how you maintain them. Young mechanics and techs can learn a LOT from watching your videos. I watch to refresh my memory and keep myself current with new HVAC developments. Well done! Keep 'em coming....
It looks like a disaster waiting to happen to them when observing the mess of wires in the attic and burnt wires in the main box. One wrong connection or mixup can lead to cascade of failures.
Insurance fire claim waiting to happen.
That Ratts nest was NOTHING like I've seen especially in downtown Boston. There's no ceiling height, nor any parking, the buildings have been renovated multiple times, and they're always in a hurry to get the cash register running. The same people with money own these stores/restaurants and they'll often use the same cheapest subs they can find and use them on every job. If that sub doesn't take pride in his wiring, he'll leave spaghetti on every job he does. Believe me, it gets far worse than this. I think they were hiding that contactor up there because it cold have been mounted in a closer visible area using much less wire, time and energy above a ceiling on top of a 10' ladder.
My brother worked for a company with high voltage current draw equipment, he started adding amp and voltage logging devices, (on the failing equipment), all readable on a display screen. Very helpful for longer term monitoring / trouble finding. (Provides date and time also, for other building factor(s), correlation). I recall one of my sites, that had a power-factor meter, kept pointing to a specific panel with a suspected chiller trouble, (while compressor was running). {Try and find someone who fully understands AC inductive load troubles, you have found a treasure in electrical work}. 😊
Your ear placed on the end of a screwdriver handle to a screwdriver where its tip is placed on the housing of a bearing will very often pick up a raspy bearing even in a noisy environment. Poor man's stethoscope... :)
I use this to diagnose engines too. Moving around can isolate which valve or which bearing. Don't get yer mullet caught tho.
Auto mechanic here, the long screwdriver trick you just described works quite well for diagnosing bad alternator bearings, but the problem is that I keep needing to buy longer screwdrivers because it seems every model year or 3 they bury the dang alternator under more stuff!
An intermittent dropped phase (since they share power) would cause both motor starters to drop out at the same time. Since that contactor in the attic is supplying power to the unit, it's likely that contactor (or the breaker) has an intermittent issue.
That wiring in the attic looks like it needs some maintenance using a shotgun and start over. The color mixing seems a bit wonky too.
I don't have a problem with a switch operating a main contactor, especially with 3-phase. But then keep everything in the same box, nice and tidy and label every wire so there's no question about what goes where.
@@ehsnils and that's before answering the whole question of "does it even need to be there in the first place"!
Sudden cutting of power causes a current spike from each motor tripping the motor starters right? Is the contactor something like a solenoid activated relay? I thought it was likely that bad bearings which cause more friction (increased torque/ current) combined with the motor starter current being set to low current would have tripped the motor starters but that's only probably going to happen at start up. What you commented seems more likely.
Phase imbalance will get a 3 phase motor every time. At a minimum, windings overheat and if thermal protection is wired up the controller drops out - varnish breakdown can agggravate too, or result from an otherwise temporary supply condition. Phase savers are a beautiful thing...
@@flinch622 I have those phase monitors on the 600V air compressors at work, they are a lifesaver, probably they saved the compressors at least a couple of times.
Whenever you find extra stuff hidden in the ceiling, you know it wasn't set up correctly. I work in IT, and we were looking all over for a set of network cables runs and another switch. Finally, we found 24 cables running on an extension cord in the ceiling where at some point, they removed the wall and cut the cables short, so they just stuffed equipment hidden. It explains some of why their network was so bad.
Been there, done that. Hidden equipment always ends up being a pain in the @ss.
@@metrotechguru5863 it's spelled/written ass
I will discuss this on my livestream this evening 02/07/22 @ 5:PM (pacific) on CZcams come over and check it out czcams.com/video/AjnU2FRoRiA/video.html
Ehh. I wouldn’t say thats true at all. Ive seen some crazy shit manufacturers call out to do. They always have their reasons. But its usually out of redundancy. But in this case, yeah, this was extra shit that wasn’t necessary.
I'm going to agree with you this time about that contactor! Or, definitely something in the supply to those fans dropping a leg and causing the overload.
I think your final diagnosis is spot-on. We do not know the age or condition of the attic contactor, or even if that rat's nest of wiring is done properly - and you've already ascertained that the manual hood switch overrides the automatic fire suppression system, which I'm reasonably-certain violates fire codes. If it doesn't, it should. Either way, it needs to be addressed - I would have enjoyed a "down the rabbit hole" video on that mess, but I don't blame you for handing it off to an electrician to sort out!
The fact the surprise contactor supplies power to both the hood and the MAU starters, and those two starters are the only ones affected, really drives your final theory home. The dead dishwasher exhaust was a red herring, but you found a failure the client was unaware of.
21:00 and that is why you use wire ferrules/sleeves and a screwdriver with a torque setting.
Great call. Huge problem in industry today, 1 - customer pays to have higher end controls installed, 2 - yet weren't installed correctly by competent person. 3 - They were never started by competent person, 4 - no description of operation / no as built wiring diagram readily available for service personell. Yet what does customer say? "what's taking so long! It's just an exhaust fan!"
Nor was it checked by the Fire Marshal and Mechanical Inspector before issuing the Certificate of Occupancy. This would have been corrected to allow the customer to open for business.
Burnt wires:
I started working at a place that had me design some fairly large water heating units that ran at 115V
We had nothing but trouble with these units melting wires, contactors etc.
What stopped all the issues was investing in some torque screwdrivers. What that tool showed me was how stupidly overtight I have been making connections all these years, and until I did something that carried REAL power, the problem was hidden from me.
Thanks for the detailed lesson. Captive-Air hood systems are well made but complicated for service HVAC & installation electricians. Having the Captive-Air tech go through the finished installation has been valuable for me. They find what you are finding very quickly and give the owner a second opinion that's very authoritative. I think you nailed it in the summation. In my experience, most electricians have little control education outside of light commercial. They know contactors but not relay logic. Control people like Johnson & Honeywell Controls learn the ins and outs of advanced HVAC controls.
I appreciate your approach to diagnostics. Also you don't "squirrel" and get out of the scope of your initial work order. That is reall easy to do and it costs your company money. I appreciate your videos.
That looks like the exhaust fan controller we used at Lone Star Steakhouse locations back in the day. The exhaust fans were interconnected with the fire suppression system and the main gas valve for the kitchen....
If the blower blades are greasy and dirty, that can add a tremendous extra weight to what the motor has to turn, which can cause overamping in high ambient and constant use. It'll do a mystery trip for no apparent reason. When motors go out on thermal overloads too often, it cooks the windings and bearings, so yeah... bad motor... but filthy blower wheels are what wear out the motors to start with.
Schneider has some nice contactor bridges GV2G245 (2 contactors 45mm) then you don't have to make bridges also use Wire-end ferrules with plastic collars ;)
You are right those are learning moments and thank you for taking us along with you so we can troubleshoot an issue like this in the future. Thanks for the video Chris.
I know what you mean about reflecting on things. I always used to worry about making a mistake at my job that would cause harm to someone else. So I used to reflect or go back after I was done and I got so good at it I could retrace every step I took. It’s an amazing tool your mind is. Thanks for the video I really enjoyed this one
This video (is one of many) is a Great example of why I feel your channel is so popular. You're consistent, methodical troubleshooting to start with. Now, I don't always understand some of the things you're describing, but that only due to the fact that I haven't seen or worked on what you're describing, plus you can't always show full details through filming (for obvious reasons). You have a style of filming that's easy to follow, and I absolutely share your passion for really digging in and figuring out what the problem is. And especially dig what you said about the learning experience. I have my own examples. I really appreciate how you explain things, you have a gift man, you really do!! My only regret is finding your videos after I had to stop doing this work. I have No Doubt they would have been a fantastic resource! Thank You For What You Do!!😁😎
I always LOVE the electrical troubleshooting episodes like this. I always think, "What could possibly go wrong with the electrical system?", and yet you always find something that has indeed gone wrong.
I wish you would put a mechanics stethoscope to all motors. You would be amazed at how much more you can hear way before failure happens.
That was an awesome service call. That's what happens when you have different hands in the pot
It's quite common in a hospital setting to interlock an exhaust fan "electrically" with a supply fan. This is done to prevent pulling negative air pressure in certain areas such as Operating Rooms, Nurseries, or other Patient areas like Isolation Rooms.
I was the prototype model maker for those Hubbell motor starter switches and ally enclosures.
15:40 that's why I started to crimp even solid wires. It increases the material strength in the area where you screw on the lead and it avoids that you bent the wire too tight right at the point where the insulation ends.
Service factor of 1.15 or lower= set overload to 10% above of RLA. 1.25 and above set overload to 25% above of RLA.
Excellent video - thanks so much for putting this stuff out.
I don't know sh__ from shineola about electricity, but recently I installed a Homewerks blue tooth bathroom exhaust fan so my wife could listen to music while she showers. When it came time to figure out how to wire the three wires to the switch so all of the features would work, well, my wife had to do it. What I am saying is, I don't know squat about electric yet you had me mesmerized for forty minutes watching you work. You really know your business mister!
The inrush of the supply being energized without the starters (they’re always engaged) I assume is causing them to trip on inrush.
Wouldn't the starter be designed to ignore inrush current?
@@nickwallette6201 indeed they should/do. They’re just a resettable breaker tied to a contactor.
But I’m wondering if both are always on, and that relay engages, that’s likely going to sag the single 20a feed they’re sharing and cause a longer overcurrent situation than if they were each triggering independently (even if one engaged right after the other).
I’m likely wrong. It just seems the wiring of a contactor down stream is just a bad idea.
The was indeed a good episode. Keeping up with codes is a full-time job.
Awesome job. Every time I noticed you caught a problem was when it was completely quiet. You probably never would have heard that contactor otherwise.
Love watching your videos. My coworkers should. As a TAB guy seen a lot over the years. These smart hoods can be a pain programming sometimes. Someone probably couldn't figure it out and said I know how to fix it with spaghetti and relays. Those rotation stickers aren't always correct. Reading the amp with the leads connected failed me in a test once (safety strike/auto fail) Keep up the good work. You are very thorough.
Well I didn't plan on visiting the hub today but.... I got to "give it a good tug"
Something interesting that I saw, not related to issues, when looking at one of the running motors, was that it appeared the pulley looked like it was not spinning. Of course it was, but , because of the video capture, the spokes of the pulley was in the same physical position when each frame was captured. For safety, that is why you make sure that power is locked out before putting your fingers near the belt. A similar effect occurs under florescent or arc lamps.
This is the way a strobe light works.
Some kinds of LED light fixture and/or lamp have a similar effect as fluorescent and arc lamps, it depends on the specific driver circuit used.
Unlike an incandescent bulb, LEDs, fluorescent and arc lamps all respond really quick to electrical input.
If I came across a similar issues I would advise the customer this could be a problem if a fire occurred could nul and void their insurance. As the restaurants were owned by the corporation and not the licensee who was responsible for the maintenance I had to advise corporation, with licensee knowledge, to cover my back.
13:45 RESPECT for not hiding having 3 hands - most (if not all) hide such deformity, perhaps in shame, who knows..... WELL DONE !!!
on a balanced 3-phase system there should be *no* current at all on the neutral. If the neutral is burned there is definetly something wrong down the line.
I thought the neutral was only on the 120v coil circuit which would carry current.
@@bobh6728 It is
Chris , great video and NOT to long.. Thank you
This video is the exact reason why I don't agree to just fix this exhaust motor. It's not in my wheelhouse to understand the controls. I wish I could dedicate the time to get good at it, but I don't. This is a prime example of your smarter to walk away than take on a job your not qualified for. My biggest request is walk in coolers but I decline Everytime, just not worth it for me or the customer. What really ticks me off is returning and seeing that the hack got the job and would have been better off with me. Our field is so vast no shame in limiting what YOU specialize in. Definitely learned alot from your videos maybe one day I'll branch out more
Really great informative video thanks
Great Job! I understood your explanations and logic.
I don't work in this area at all but this was super interesting, thanks for the in-depth video and commentary.
The electrician was on a good one running all that wire
The other reason they force the exhaust fans to turn on when the fire suppression system triggers is to help draw out any smoke, thus improving visibility for people trying to leave...
I think the contactor inside the ceiling is from the previous set-up to run all the EF anf MAU before getting up to code.
Great video !!!
Awesome job as always
17:50 eww... wire nuts. You should really start using WAGO connectors (those with the clamping arms). There are 1:1 connectors for multiple phases too. So you might just need one connector for all the wires.
Brilliant diagnosis. 👍
Great video! Thanks!
I really enjoyed today's video as I was also digging WTF was going on during the contactor on the addict.
Very good troubleshooting!
You did awesome work to look at the big and step by step to figure out what wrong everyone is not perfect we are only human great video
Glad the Fire Marshall's are doing their inspections! 😁👍
Thank you so much for sharing really interesting I so all video
Great video, keep up the great videos.
In retrospect, having two independent motor controller tripping at the same time for no real cause should have raised suspicion about incoming power sooner. But I don't know if that would have led you to finding that contactor. That was unexpected.
A very interesting and excellent video. I do wonder however if that place ever fixed the fire suppression wiring. I would like to think they did if only for insurance purposes.
I run in to a lot of similar situations in the stuff I do (CCTV/PACS/Alarm) where the call out is simple but it turns into a huge complex stack of issues and none of them are a good candidate for an apparent cause. I also enjoy the so-called "aha" moments because they're fewer and further between as experience goes on, but the discoveries along the way definitely account for a substantial base of future troubleshooting steps. Finding the needle in the haystack is such a release, it's a rush when you find it.
1:55 When you tone out the switch to check for a dead short, you should also check the line side too...the short if there is one might be on the incoming side of the switch between the breaker panel or motor control contactor and the switch...
Not before Isolating and applying a personal lock to the circuit. Also bad practice to have multiple "Live" terminal boxes opened and exposed in different locations on the roof.
21:08 remember to use a torque screwdriver every time you connect some current carrying connection with a threaded fastener! Almost no tradesmen in the US do it, but it makes the difference between a 95 reliable connection and a 99.99% reliable connection!
Every time I sit down to watch one of your video, I received an emergency call!
Big picture diagnosis tech great job Chris 👏
Great video!
I think, I could be wrong, some of the ANSUL systems also have extinguisher heads pointed at the equipment and will release the extinguisher contents whenever it senses a fire as well. Also, if the kitchen hoods are full of grease, wouldn't that be pretty dangerous just having to rely on the hoods to suffocate the flames?
There are nozzles that point to spray the area, yes. They also shut the dampeners to help prevent exhaust hood fires. The potential grease build-up in the Gaylord hoods are supposed to be washed down every evening at the push of a button to help prevent hood fires. Sorry if that doesn't quite make sense.
The entire custom/racing wing, and two others, of the National Motorcycle Museum in Birmingham in the UK burnt to a crisp when some underpaid, underqualified .. ahem.. "individual" threw a lit cigarette out a window of a cafeteria kitchen. it landed in a dumpster (as you do), it lit the dumpster on fire (as it does), and the fire in the dumpster lit the verrrry greasy UNMAINTAINED exhaust hoods on fire, drawing the fire into the building (presumably adjacent to aforementioned wing/buildings 3-5. There was a fire detection system so no fire suppression system, so when the trucks arrived, the conflagration was well underway. Then, there was NO hydrant nearby (as you do!) so they ended up drawing some water off of the reflecting pool (as you do) to limit the fire to the one wing and not make the entire museum a TOTAL LOSS. Fortunately for me I, two months before this occurrence, on a whim, visited the museum for the 2nd time in a few years, taking tons of pics of what I was interested in... what an utter, complete, sequential, multiplicative, cluster f**k.
Gotta love a nice, simple call.
Tip from a high volume photocopier tech. If you want to isolate a noisy part in a loud environment take a long screwdriver, carefully put the tip to the part in question and press your ear to the end of the handle. The mechanical noise will easily conduct up the metallic shaft and you will hear very quiet grinding or clicking as loud as day.
good definition of don’t just the book by the cover 15:30 😂
I would not turn up the trip amperage knob on motor overloads past the name plate of the motor's RLA. The current setting you see on motor overloads already allows for 115% to 125% beyond what you see on the knob unless it is very old design, which require setting the trip knob above RLA after doing the calculations of the RLA at 115 to 125% rating depending on motor service factor. Max allowed is 140% above RLA per NEC for special situations.
thanks for the share, subbed
Hi ! very nice. I always love to watch your videos.
Nice to see someone who actually really understand what he is doing, and on the other hand, not rush to areas which is out of his scope.
BTW, - COOL WATCH ! Can you tell me what it is? (-:
I agree with you. That rat's nest in the attic with the contactor was the issue.
"They are independent after incoming power..."
If that's the common cause, electrical problem is likely. Consider the following: Makeup air unit that due to changes in pressure in the building, increases current draw. Then the exhaust fan starting up inducing high current. Could this cause a voltage drop on the circuit that trips the starter?
Lower pressure in the building would mean less air available for the exhaust wheel to accelerate, leading to lower amp draw... Higher pressure in the building would cause the make-up air unit to have nowhere to send the air, causing less air to be able to enter the blower, making less mass to accelerate, lowering current draw, after an inrush. It would have to be a pretty epic and sustained even to cause it, regardless.
@@niftyjig I thought the makeup air unit is more fighting against the pressure differential between outside and inside...
No - but pulley ratio can affect motor load for a given fan design: if it's on the edge, bearings going out will begin pushing the motor into overload. I was thinking seriously pitted stabs or weak clips in a breaker panel can effectively de-rate a breaker. A 20 amp breaker might become 12 [in providing full voltage] for example, and a 16-17 amp load that would normally be zero problem finds itself with an undervoltage condition - motor loads will pull extra amps in an undervoltage condition and make the controller trip. If it was the Ansul system screwing things up, starters would just drop out and no overload trip. Sequencing starters might help here: inrush current of all three motors starting simultaneously might be a touch more than the breaker should see - something as small as a 1 second delay between motors might do wonders. Absent that, change breaker types. This is one of those situations when picking an operators brains is important [find out their routine], and... finding out what the last thing fooled with was.
He guessed that the motor starter was dropping voltage near the end but... I missed the part with him putting a voltmeter across it from line to load side - if it was "dirty" voltage drop would be present. I do wonder about the mystery contactor in the ceiling... was the exhaust hood replaced and instead of ripping out the old controls, a problem redundancy was created?
6:05 at 208 it will actually be a little more......but you get a pass Chris, i know that sun is hot up there LOL!
Excellent vid tnx
I’ve always felt amazing opening up a MUA which serves the food processing area only to find all manner of filth within…and the best part is finding the HVAC P/M tech’s signed and dated tag showing that complete service was recently provided.
-NEBB Certified TAB EnGuneer
I think the side switches for fans at control panel are for bypass the temperature controller or force the fans to work
Have to say that was one good lesson I will remember it
reason for "coupling" or interlocking to stop pressurization or depressurization of the building in case the mau or exf fails. if this was working in low temp with a direct fired mau it would be dumping products of combustion into the building with out removing it with no ex fan.
A thought. I pulled the sheet for the PXR-4 controller units seen in the panel. I believe the right hand unit is slaved to the left hand unit. That way, a single temp probe at one site provides the required controller chain input value. The right side still requires a set value to trigger a response...here, and correctly, set to the same action temp of 85F. This is fine if all the control devices are operated in the same manner under the same conditions. It's not fine because your entire system is reliant upon the only probe available. If that probe were to fail, the entire system fails. Critical area redundancy costs more but also increases protection.
Nah that wouldn't work here because there are multiple hoods that are nowhere near echaother, if the fans were under a common hood than yes it could be programmed that way but since they are independent they each need their own temperature override .....
I think it'd be easy to fall into the trap of "hindsight is always 20/20" by saying that there was something better or different you could have done. Intermittents are a pain. Everyone's going to have their own approach to solving the problem. My first thought was "there has to be a phase being dropped somewhere". That contactor sure is a suspicion.
These exhaust systems are not even remotely in my wheelhouse, but assuming I followed the wiring correctly, I thought it very odd that the hood switch would also control the make-up air unit. (Unless, of course, that was someone's effort at air balance?) I also saw a white wire tied in with the green ones up in the "attic", so I'm guessing they might also have been abusing the ground to get a "neutral".
In closing, I'd also like to ask if you'd consider putting the generic HVAC/R logo from the hats on a shirt and/or sweatshirt. Being a one-man show who does HVAC/R entirely on the side, I don't have "company" shirts of my own, nor any desire to create some, and I'd certainly buy some generic HVAC/R logo shirts if you offered them...
There really isn't anything more you could've done, unless they paid you to trace those other wires in the "attic contactor" to see what they went to. Things like this are a PITA, but I love a good electrical challenge that makes my brain work!
Didn't you post this video before I'm having deja vu, with the exact same issue including the missing sensor. it was a few months back and you added a sensor.
No that was a different call at a different location, id say that video was from a year or so ago
Love the videos and the 4K 60
It is my understanding that in the event of a range hood fire, the exhaust fans are kept running primarily to remove smoke and the products of combustion (CO) as part of life safety code.
Mine were in schools and shut down at night so they could not run in un occupied mode and the fan shutdown mode when fire alarms activate. You might find that hidden panel has a control wire going back to a control module elsewhere.
Seeing schneider modules after all the crapped out shit from the 80s feels like you got teleported to the space age
I think the attic contactor is the issue. The other thing is in the morning when you start up you have two motors starting at the exact same time
I had a panel where someone had paralleled a spare exhaust motor contactor to the MAU contactor. I had tripped the spare exhaust contactor on a previous call for MAU not shutting down during testing. Someone behind me had reset it and did not look at what was going on. Got another call for the same thing and pulled the neutral for the contactor coil. I will not shut down a store when they are actively cooking to remove the extra connections from the exhaust contactor.
We use to change bearings in otherwise good motors. Do you ever do this or just throw away good motors that only need bearings? Thanks for the video, it was an interesting case study.
I wouldn't say that you "throw away" a good motor with bad bearings when you dispose of it, usually with things like electric motors (at least in the automotive world, but it should be similar most other places), when you buy the new one they'll ask you if you have an old one to give back, and if you do they'll often give you a pretty significant discount on the new one. This is called a "core charge" because everyone involved knows that the "core" of the thing is probably still at least mostly useful when combined with other working parts, and motors have a number of different reasons that they fail, and there's a whole industry built up around re-building these things.
Granted, you used to be able to go to a relatively local shop to have any given motor re-built (likely up to and including re-winding the stator and/or armature, depending on the type of motor), but those days are pretty much gone and now motors get rebuilt en-masse in a large factory somewhere overseas.
Still probably at least one shop doing it in any given highly industrialized (or formerly industrial) city in the US, because sometimes it's more about minimizing downtime than it is about saving money, and sometimes the motor you need rebuilt isn't just something you can easily get off the shelf anymore. But it's not the kind of thing where everyone in town will know where they are.
@@44R0Ndin Automotive electric motors usually have bushing type bearings that sometimes can be oiled and they can be sent a rebuilder. 1/2 to 10 or 20 h.p. high voltage motors usually have ball or roller bearings that can be easily changed in a short time and reused if the shaft is o.k. and the rotor has not contacted the stator. I have changed many of these over the years with no issues. Sealed bearings are easy to change. Most of the time people over grease bearings that have places to grease them. You have to remove the small plug in the bottom of the bearing and then grease it so it is never over greased and then re- install the plug. Most people never remove the plug and fill the windings with grease.
@@watermanone7567 I do have some experience with the higher voltage motors, seeing as there's one driving the pump on every air compressor I've ever needed to interact with. The bearings are indeed easy to find replacements for, and easy to get at with the type of compressors I've always seen used in auto shops (piston type air compressors, often at least 2 stage to supply air at both high volume and high pressure to run things like impact wrenches and tire machines).
I grease the bearings every time I change the oil in the compressor crankcase, but on the motor for my compressor specifically there's just a grease fitting and a tiny hole (1/16") to let the grease out, with no plug for that tiny hole (only reason I even know about the hole is because I saw grease come out of it). The way they have the motor mounted, the grease fitting is on the bottom and the tiny hole is at like 2:30 on a clock face
I'm well aware that this is not an ideal arrangement, but I did notice that the bearing they used is a "half sealed, half open" type, rubber seal on the side where there is a small passage leading to that tiny hole, and there's another passage leading from the open side of the bearing to the grease fitting.
I guess what they did is that they made the bearing "more idiot resistant" with regards to maintenance by replacing the "you have to remember to remove and replace it" plug that you've found on motors with a rubber seal that will let a little bit of grease thru when faced with the pressure from a typical grease gun. This also lubricates and flushes any potential debris out of the sealing surface, which can't be a bad thing, right?
Seems like an elegant engineering solution, but selecting the right seal that has the right amount of tension to maintain on that seal must be a tricky choice. I do notice that the bearing is a little more expensive than bearings of identical size but differing seal configurations. It is hard to get a tool near that weep hole (I can get a shop rag in there to clean the grease away after I'm done, but it's not easy), so maybe that's why they did it this way?
This was a good one
Great video! To check your theory on the hoods not coming on with temp because of the contactor you could have heated up the sensor that was hooked up to see if it kick on the fans. Keep up the good work and as always thanks for your videos.
That was my bet right off, especially after seeing a neutral burnt worse than the phases. That's extremely indicative that your phases are quite unbalanced. If that contactor isn't operating properly, you could end up with 1-2 phases with low voltage and so the phases that do have power will TRY to turn that motor, creating an OC situation on those phases with solid voltage.
My money's on that illegal attic contactor, since everything else is always closed-- That means it's the thing where the contacts are actually arcing, when power turns on and off, burning them up instead of the others... That will be the wear point, it will cause these symptoms, it's common to both motors.
Only thing I would have done differently, is told them to set it up properly for fire operation. If I was the landlord for that building, I would be chewing glass, right now. If that switch is off for the night, and something fails and is ignited by a pilot or something, the fans will not come on to give all that heat and soot somewhere safe to go. Soot makes a mess in a building after a fire, it could get everywhere. And if the heat is not going up the fans, it can set other stuff on fire, like the ceiling, and then it could spread, even if the ANSUL catches the initial blaze.
I will discuss this on my livestream this evening 02/07/22 @ 5:PM (pacific) on CZcams come over and check it out czcams.com/video/AjnU2FRoRiA/video.html
We were trying to get the fire system at my church to turn on the exhaust hood but never could get it working correctly. Covid shut me out so I have no idea if they ever got it figured out. There has been many changes in that kitchen but I have not been back.
Wiring nightmare! Lol only in Hvac!
Smart money is definitely on that additional contactor. One phase' contact is likely burnt causing BOTH exhaust fan motors to intermittently stall due to attempting to start on just 2 phases (just like the broken wire on the MUA unit). Just FYI ... you would see an area of concentrated heat directly at the high resistance contact, not a higher current on that phase. Ohms law dictates an elevated resistance (as long as voltage does not change) will always reduce the current on the circuit regardless of the reason.
The switch is working as an "isolator" instead of activator. It cuts the power to the entire system instead of turning off the relays. Which also cuts the power to the safety systems
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