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supermanotorious

supermanotorious

Well-known member
Joined
Jun 29, 2015
Posts
592
Location
Phoenix, AZ
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
 

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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.
 
supermanotorious said:
thank you, I was reading it wrong (idiot)

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

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

 
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. 
 
Charlie 5320 said:
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. 
Click to expand...

check out the Phoenix, AZ forecast... and btw Charlie, I also have a 496 8.1 workhorse!
 
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.
 
supermanotorious said:
check out the Phoenix, AZ forecast... and btw Charlie, I also have a 496 8.1 workhorse!
Click to expand...
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.
 
supermanotorious said:
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
Click to expand...
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.
 
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