Wow! A 4-compressor whack on RTU's (GrandPAH)

Terry_14

I was the unfortunate tech standing next to to a 10 ton when i heard what sounded like a shotgun going off with both parrals.

Situations like this should be a reminder to put all screws back on covers. Serious pain can occure worse than knealing on the screws someone left behind

Terry T.

Dave Yates (PAH)

Not your average call!

We were asked to investigate a weird RTU situation this morning for an insurance co.

First, lets start with the dangerous condition left by a previous "contractor". Compressor wires left dangling in direct contact with the RTU cabinet. No physical lock-out/tag-out and no note to alert the next visitor of the electrocution hazard. Grrrrrrr

We were told that all four compressors (two 10-ton 3-phase RTU's) were toast. Third-hand info, so we wanted to do our own diagnosis. Three year old units (RUUD - not that that's an issue). First unit: remove electrical panel expecting to find components roasted, toasted and smelly. Not a chance. They all "looked" brand new, including the PC board that had not a single trace of short-circuiting. Not that anything is expected, but a four-compressor failure isn't exactly an every-day occurance either.

Pulled the compressor cabinet access panel and found the dangling wires.

Unit #2. Compressor stage 1 blew up and the interior of the cabinet is pretty ugly, as you'd expect. Burned oil and the acrid odor you'd expect. Sure am glad we weren't standing there when she blew!

OK, so what happened? The owner finally shows up and proceeds to say all he did was turn up the thermostat (each RTU has its own 2-stage stat) and next thing he heard was a very loud BOOM. Fire dept called & units turned off at the main breaker panel.

The remaining three compressors all show a short in the windings to ground.

OK, time for a few questions from the owner with the foul mouth. F-bombs were dropping like rain drops in a torrential downpour! I'm no prude, but this guy was wasting an awful lot of energy by his overuse of that one word!

Seems their (on lot) three-phase pole fell over last fall. Lights inside the store were exploding and a customer exclaimed that there was a fire in the side lot, which turned out to be the electrical short.

New pole installed, the electrician restores power to the building and all is OK - or is it?

Mr. F-bomb swears (pun intended) that the heating worked without a hitch (well, that is the single-phase side of the RTU's after all). Right up until he turned on the R-22 scroll compressors via the themostat.

We think the pole faling and subsequent short circuiting/fire may have whacked those windings with a weird voltage spike and ripped through the windings. A second thought was that the electrician got two of the three-phase wires reversed causing the scrolls to run backwards, although I can't imagine a scenario where the thermal discs would fail to protect all four compressors.

The thing I don't get is why the fuses all failed to protect the equipment and why the electrical components don't appear to be damaged.

Danged peck-u-lar!

Thoughts???

Oh yeah, Mr. potty-mouth says he ain't paying a f'n thing to no f'n body and he bets it was the f'n electrician that f'd up his f'n units.

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Brad White_9

Classic Phase Failure

Phase failure protection is available on many units (not sure about Ruud) but you might get it as an after-market package.

I could see where that was going. Happens.

Jim Bergmann_2

Compressor Failure

Question, Is the evaporator fan three phase? If so, if the heating worked, the phasing was not backward as the evaporator fan would have not operated properly. Also the compressors could have lost a phase and burned up. Are the breakers and fuses the correct size? Did you completly disconnect the wires form the compressors and check the terminals to ground? I have seen a lot of bad wires.

Eugene Silberstein 3

In order for...

In order for a voltage spike or power surge to potentially damage the windings of a compressor, the power actually has to reach the compressor.

So unless, at the time of the pole damage, both cooling stages on both units were operating, there is no way that four compressors were lost at one time.

As Jim mentioned, I would check the compressor for shorts-to-ground and shorted windings right on the compressor itself, with all windings disconnected.

Also, finding out what caused the pole to fall might shed some light on the situation. For example, was it struck by a car or was it hit by lightning? Hmmmmmmmmm

Marty

like this ?

If the first stage compressor looked like this I have seen more than one rheem/rudd lose both stages at once always the first stage that explodes and the other grounded.

graingers sells something like speedydry but much finer that works great for cleaning up the mess.

Dave Yates (PAH)

pre-

zactly like that! Ka-BOOM

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Dave Yates (PAH)

and that's

what brought me here Prof.

A nagging thought bouncing round the back of my mind that won't stop - like a super-ball!

Why all four?

With no other apparent electrical damage?

No lightning strikes.

The pole fell down during a downpour and high winds. No car or other impact. The transformers on the utility's pole remain unchanged - judging by their rusty condition. This is a private pole on the customer's property. Nothing but a spot for the incoming wires to hang upon just prior to the building.

At three years, it's not a warranty issue for RUUD (doubtful , even if it was less than a year).

How this occured without all four being in "activated" mode is a mystery to me as well. Maybe they were, but that's highly doubtful id the owner is telling the truth regarding the time of year the pole fell down.

And, if they had been in an activated mode, wouldn't you expect to see some collateral damage inside the unit's panel? The owner's description of sparks flying from store lights and them exploding reminded me of the Hollywood special effects we see in movies!

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Marty

follow the ground

That picture was the second set of compressors (not scrolls) in that unit #6 ground in unit,open disconnect and thats where it stopped.

Empire_2

Just a thought...

I would try to put in motion a check of that T-former on the pole from the utility co. Lightning does sound like a possibility, but it can't hurt to start checking with the service coming in to the building. It's to bad that a mega ohm meter couldn't have been used to check the integrity of the windings prior to the burn. This problem may have taken a while to do it's damage. It might not be a bad idea if there is more equipment, check the insulation on the windings with the mege-ohm-meter. Get that pole checked.....

Mike T.

Brad White_80

Accidental

"Also, finding out what caused the pole to fall might shed some light on the situation. For example, was it struck by a car or was it hit by lightning? Hmmmmmmmmm"

Patrick Kennedy was still in rehab at the time. There goes that theory.

jim lockard

along with

installing phase monitors and protection. May also be a good thing to check your grounds, and find out from the power company the ohms per cubic foot of soil at your work site. J.Lockard

Dave Yates (PAH)

loose wires

the compressor wires were already removed and left lying on the metal frame. A few were in direct contact with the frame, yet no lock-out or tag-out or notes to alert us to that fact. Fortunately, no one had flipped the units' disconnect switches or we could easily have been shocked.

We haven't yet checked the voltages to verify all three phases are in tact or that the voltage levels are within tolerances/allowances, although we noted that in our report and quote with the blurbage about additional costs if anything is wrong there.

Interesting that we had provided a quote some 15 to 20 years ago for replacing the old Carrier units on this building, but that owner went belly up before the ink on our quote was barely dry! As a result, I know the voltage was 220 three phase and not 440.

The pole at the property edge that holds three transformers (it's the end of the line) did not fall down and by sight only it certainly appears they were not replaced. It was the owner's pole utilized to hold the wiring just prior to it looping over into the main breaker panel that fell down in heavy rain and wind.

Wiring from the breaker panel and control wiring to stats will also be verified in good condition before anything is reconnected (if we do the install).

Tried calling RUUD's tech service direct, but they won't talk to a tech without the local supply house being involved in a three-way call. Pain in the ****! S'ok, there's plenty of other manufacturers who don't make it difficult to speak with their tech service department. So, RUUD lost their chance to be the replacement. Not that I didn't try by calling the local supply house and getting put on hold for an eternity. I have too many fires to put out to be that patient! click

Odd way to do business if you're looking to build market share, IMHO. Time IS money & my techs must have direct access to tech service when working on equipment.

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Empire_2

Hi Dave...

Yea, I agree with your statement on cust. service. That is a why I choose not to deal with Rheem or Rudd!!!!!!!!! I don't have time to squabble over service issues.

Mike T.

subcooler

10 large

Tell Mr. Potty mouth give me 10 large and I give him 4 new comps. and a better warranty than Ruud.

Dave Yates (PAH)

he's demanding

new RTU's and won't accept just changing out compressors.

Given his 2%-er attitude going in, I'm not going to change out compressors and then spend countless hours chasing ghost complaints.

However, the insurance co will make the final call. If they want compressors only, we're not the contractor for this job. Besides which, the ins co wants a guarantee there won't be anything else wrong - that means we'd be caught in the middle between two parties where neither one will pay for additional repairs!

CYA - Cover Your ****-sets!

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subcooler

Favorite job.

You sell him 4 new comps and Secondary phase protection. The units already have primary phase protection in the original wiring in the units. The Insurance Company won't even batt an Eyelash at the job. I have done many a job like this one. But we also do about 95% service only.

Terry_14

220 v lighting

Some lights are 220 v my other question is there a wild leg on potty mouth's transformer?

I was once called in as an expert witness for a lawyer representing a family who lost a husband to dangling wires from a condenser fan wiring sleeve chase removed by another when he replaced motor.

Safty is no accident
Terry T.