You don't know how to use a library? I don't need to give you the
science, I have directly observed the phenomenon. Direct observation
makes up most science. I did find a document online that has some
equations if that will help you understand but if you know anything
about electricity, you can visualize that a length of wire has a
magnetic field when energized. Take a look at page 3 of the PDF:
I know something about electricity. I know it takes a great very deal
of current to make a strong magnetic field in a straight wire.
Possible in a commercial setting with high pulsed current, yes. In a
home ac compressor, I doubt it. Go ahead, hold your ferrous
screwdriver blade near the 10 guage wire with the compressor running.
Feel any pull?
You obviously didn't understand, the wire movement happens when the
compressor starts, not continuously. The compressor starts, you can
hear the breaker buzz and the wires in a conduit jump, rattle for
a split second, not during normal run operation. GEEZ!
There is a circular magnetic field around a conductor carrying current.
With 2 wires carrying current both ways in a circuit, the magnetic field
pushes the wires apart. The starting current for a motor is about 6x the
running current. Seems to me you might hear wires moving in some cases.
Like I posted to someone else, the noise sounds like a steel fish tape
rattling around in an otherwise empty conduit. It's a distinct sound.
Sometimes it sounds like someone whacked the conduit once with the metal
shaft of a screwdriver, the sharp noise seems to travel down
the length of the conduit if you understand what I mean. It's
unmistakable when you hear it, you may even hear the breaker buzz too.
High current --> wires heat --> heat causes expansion --> expansion
causes movement (not exactly "rattle" perhaps, but insulation sliding
against insulation could probably approximate a squeak)
Am I missing something? What's so hard to understand?
First, you haven't quantified the surge current.
Second, he didn't see it, he heard it. Things that appear still can
make noise -- consider a piezo speaker.
Third, the other poster has offered an alternative explanation.
The inductive kick of a high current motor/compressor start can cause
wire inside a metal conduit to make noise. I've heard the telltale
racket a million times in many different settings. It sounds a lot
like somebody shaking a metal fish tape inside an empty conduit.
I wonder what will happen when one of the wire dancing deniers first
hears that sound. Hummm, must be a big rat in here? 8-)
It's probably THHN insulated wire which has a clear Nylon outer jacket
that is slippery making it easy to pull and chemical resistant. The
slick jacket may keep it from abrading unless it's on a sharp metal
It runs but is it fixed? He said it was out of freon and he bypassed
the 5 minute timer circuit thats for my old Honeywell thermostat. But
It was just filled 3 weeks ago by the same company but different tech
fixed a leak, but there is nothing leaking where it was fixed. Here is
where I get suspicious, last time it failed it took a few days to leak
out and I noticed it and saw ice on the coils, this time it just
stopped cooling and the handler had no ice. I know the tech has no
motive to lie but having the timer and a leak??? But he didnt charge
me when he found out they were out a few weeks ago, so, I will just
see if it all leaks out again, the date on the compressor is 94 so it
may have run its life but I cant afford a new one anyway, hey summers
about over so im not worried. They want 300 for just a leak test and
he thought I would say yes yes yes, but I said no. I see leak
detectors for 29$ on ebay and 75 at HF so maybe I should get one for
fun and saving a 300$ test.
You can mix a big squirt of dish soap with a cup of warm water. Paint
it on with a brush (on the copper tubing) and some where you might
find where it blows bubbles.
And like you say, buy your own leak detector. I sense that HVAC
company is expensive, and not very service minded.
You must have another leak or the first repair was flawed. The mormon
is right, soapy water is not a bad leak detector. The cheap leak
detectors are not much better than soapy water. Unless it's in the
evaporator coil. Big leaks are usually pretty easy to find. I'd
start where the first repair was made.
You paid once for them to find leaks. I'd be on the phone with the
manager. When I had someone find a leak in my upstairs unit they went
over the entire system even though they found one leak in the
evaporator part way through the check. They used a leak detector but
it was not a cheap one.
It's also amazing that they would just refill it with refrigerant
without doing the leak test. They repaired a leak and filled it a
few weeks ago. Obviously the refrigerant went somewhere. You would
think they would just do the leak test for free while they were there
rather than screw around.
I guess the worse case is that it's leaking somewhere other than where
they repaired it. If so, I guess you're out of luck because they're
likely going to say they only guarantee the particular leak they
fixed, not a new one. Of course if there is another leak, it could
have been there all along too. I guess the question becomes, if there
is another leak, is it worth continuing to try to fix this or time for
a whole new unit. Also consider the tax credits available this year.
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