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Author Topic: HVAC question  (Read 242 times)

supermanotorious

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  • Posts: 527
    • Phoenix Winch LLC
HVAC question
« on: August 10, 2017, 05:46:32 PM »
I just built a misting system for my a/c unit, it's a Goodman packaged model. I control the water flow through a sprinkler solenoid but the problem is I'm not getting 24V from the contactor's coil on the a/c unit. The a/c unit is running and running well. Why am I not seeing 24V across this coil?!

I didn't think the unit would operate unless 24V was across the coil, there is no problem with the compressor coming on
« Last Edit: August 10, 2017, 05:53:30 PM by supermanotorious »
Home is Phoenix, AZ
2008 Skyline Freestyle M-240 Way-Lite
2003 Harley Davidson Dyna FXDX
2003 Chevrolet Avalanche 2500 8.1L 496ci 4x4
1994 Four Winns Freedom
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catblaster

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  • Posts: 2132
Re: HVAC question
« Reply #1 on: August 10, 2017, 06:19:35 PM »
It may seem like an obvious question to ask but are you trying to read AC or DC on your meter? Aso you probably already know this too but you will not get any current flow until the t-stat calls for cooling and that is the #1 compressor contactor.
Will and Jane
95 Winnebago Luxor

supermanotorious

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  • Posts: 527
    • Phoenix Winch LLC
Re: HVAC question
« Reply #2 on: August 10, 2017, 08:04:15 PM »
thank you, I was reading it wrong (idiot)

https://www.youtube.com/watch?v=Z3jTIXHHbS4 
Home is Phoenix, AZ
2008 Skyline Freestyle M-240 Way-Lite
2003 Harley Davidson Dyna FXDX
2003 Chevrolet Avalanche 2500 8.1L 496ci 4x4
1994 Four Winns Freedom
various quads, off-road gokarts, mini bikes
Phoenix Winch wakeboard winches

Arch Hoagland

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  • Posts: 1407
  • Clovis CA
Re: HVAC question
« Reply #3 on: August 10, 2017, 08:46:35 PM »
thank you, I was reading it wrong (idiot)

https://www.youtube.com/watch?v=Z3jTIXHHbS4

You're not an idiot...Show me somebody who never makes a mistake and I'll show you somebody who never does anything.

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Charlie 5320

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  • Posts: 1939
Re: HVAC question
« Reply #4 on: August 10, 2017, 10:09:53 PM »
I wouldn't use that unless the outside temp is over design, which is 95 degrees. May be have it come on at 90 degrees. The contactor can be energized with a outdoor stat. The system relys on head pressure to work efficiently, and if you run the pressure too low [cooler evening temps] you won't have the flash gas to have the system work correctly especially on a orfice system. 
2003 National Dolphin 5320
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98 Damon Daybreak 3130
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supermanotorious

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  • Posts: 527
    • Phoenix Winch LLC
Re: HVAC question
« Reply #5 on: August 11, 2017, 07:52:19 AM »
I wouldn't use that unless the outside temp is over design, which is 95 degrees. May be have it come on at 90 degrees. The contactor can be energized with a outdoor stat. The system relys on head pressure to work efficiently, and if you run the pressure too low [cooler evening temps] you won't have the flash gas to have the system work correctly especially on a orfice system. 

check out the Phoenix, AZ forecast... and btw Charlie, I also have a 496 8.1 workhorse!
Home is Phoenix, AZ
2008 Skyline Freestyle M-240 Way-Lite
2003 Harley Davidson Dyna FXDX
2003 Chevrolet Avalanche 2500 8.1L 496ci 4x4
1994 Four Winns Freedom
various quads, off-road gokarts, mini bikes
Phoenix Winch wakeboard winches

kdbgoat

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  • Posts: 3948
Re: HVAC question
« Reply #6 on: August 11, 2017, 08:17:45 AM »
One thing about the misting units, I have read that they can pretty much destroy a unit but rusting out the frame and destroying the coil faster than what normal rain will do over the lifetime of a unit. You may want to check out the 'net for comments made by HVAC techs that run into this on a regular basis.
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

Charlie 5320

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  • Posts: 1939
Re: HVAC question
« Reply #7 on: August 11, 2017, 11:07:17 AM »
check out the Phoenix, AZ forecast... and btw Charlie, I also have a 496 8.1 workhorse!
You probably do need a mister, but I'd still run it off of an outdoor stat. We have had to use misters before up here to keep them running. I worked at a local hospital for 18 years in the HVAC shop, and we HAD to keep our air cooled units on line. Sometimes that is the only to keep them running.

Spraying water directly on a coil can cause unrepairable damage, but haven't seen any damage by misting them. When the temp is 105 and high humidity to boot, that's the only way to keep them on line.

Hope the misting works out for you. We had ours spraying the top of the coils and just put enough water on them to keep the coils wet. I had days when I even had trouble keeping our chillers on line because the engineer that designed our chiller plant used 95 degrees. The new plant was designed at 112, but I had a hard time talking them to do that. Cost a lot more money to do it, but at least the chillers stay on line now.
2003 National Dolphin 5320
496  8.1  Workhorse

98 Damon Daybreak 3130
GM Vortech 454  4L80E
SOLD

Charlie 5320

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  • Posts: 1939
Re: HVAC question
« Reply #8 on: August 11, 2017, 11:12:46 AM »
I just built a misting system for my a/c unit, it's a Goodman packaged model. I control the water flow through a sprinkler solenoid but the problem is I'm not getting 24V from the contactor's coil on the a/c unit. The a/c unit is running and running well. Why am I not seeing 24V across this coil?!

I didn't think the unit would operate unless 24V was across the coil, there is no problem with the compressor coming on
Another way to do it is use a 3 phase contactor and use the third set of contacts to power your sprinkler solenoid. I'd still use an outdoor stat, to control the sprinkler solenoid, so it would only work when needed.
2003 National Dolphin 5320
496  8.1  Workhorse

98 Damon Daybreak 3130
GM Vortech 454  4L80E
SOLD

 

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