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 Post subject: A Funny Story
PostPosted: 20 Jul 2017, 20:51 
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Joined: 04 Jun 2008, 20:59
Posts: 3423
Location: Arizona, USA
HI Everyone, how my afternoon went.

Funny story for the day. We live in Arizona. So do a lot of other folks. To keep cool many older house are equipped with what is commonly known as a “swamp cooler”. This device is really simple and consists of a large metal enclosure with louvers that contains absorbent pads (wood fibers or plastic woven ones like a big nylon scrub brush), a water reservoir, a pump that pumps the water to the top of the pads and a large blower that forces air into the house after sucking it through the pads. Evaporative cooling. It works very well when the humidity is low. Rather badly when it is not. Our house had one when we bought it. So much for HVAC 101 theory. We replaced it last year with a heat pump system that both cools and heats. It is quite effective and we love it. So when we started to hear a sort of oscillating sound like a cyclic whistle it was a bit disturbing to say the least. It was just loud enough to drive you nuts. It started every time the compressor in the heat pump started and continued as long as it was running. We called the company that installed the unit as it was under warranty. They promptly dispatched a service tech to check it out. He heard the sound but could not identify it nor find it. The unit was checked out and running perfectly. This went on for over an hour. After checking everything imaginable he started to look for other causes. We found it finally. The compressor was setting up a tiny resonance in the walls (this is a big unit…about 5 ton cooling capacity under the older size measurement methods and is on the roof). This in turn was being picked up by a nick knack shelf in the kitchen and causing two coffee mugs (that were just touching) to “sing”. The tech had fun writing that up on the trouble ticket and figured it would make for a great tale at the day’s end shop meeting. A true first and hopefully last occurrence. :D

Good listening
Bruce

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 Post subject: Re: A Funny Story
PostPosted: 20 Jul 2017, 21:51 
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Joined: 08 Aug 2009, 03:11
Posts: 2040
Location: Chilliwack, BC
Awesome detective work! :thumbsup:

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 Post subject: Re: A Funny Story
PostPosted: 22 Jul 2017, 14:43 
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Joined: 19 May 2011, 05:38
Posts: 23
Clamp a weight to the discharge line of the compressor.(1/2 piece of steel rod about 4-6 inches attached firmly with a hose clamp.) This should stop discharge line pulsations.


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 Post subject: Re: A Funny Story
PostPosted: 06 Sep 2017, 16:15 
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Joined: 02 Mar 2009, 12:41
Posts: 1004
Location: Vänersborg, Sweden
Great story gofar. It's wonderful that you always tend to look at wrong places when somethings working strange.

Talking of faultfinding, I heard this story back in late 70's by the technical director of Atari that made the TV arcade games.
The PCBs for the games were populated by some 50 - 80 TTL chips laid out in a nice matrix on the pretty large board. The chips were identified by the position: horisontal A, B, C ... and veryical 1, 2, 3, ...
Once they got a call from a not so skilled technician, explaining the kind of game and what the problem was. The Atari staff quickly identified the problem and gave the advice " Cut out B3!".
After a week the board turned up at Atari with the position B3 sawed away and a note saying "Cut out B3, still doesn't work!"

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