Outside AC Unit - efficiency improvement

[TWConway]

Here is what I have:

A water mister that I built out of 1/2 PVC pipe and .7 GPH misting nozzles. I have a total of 6 nozzles surrounding my outside unit. In the past the unit on my house ran from noon to 9PM, never shutting off. Builder had put in undersized unit that would barely cool the house. The small amount of water (4.5 GPH) would help the coils transition heat more efficiently. I could use a thermal heat gun and see a difference in the air temp on the vents. Because the unit ran almost constantly, I installed a simple timer on the water faucet that turned my mister on st noon and off at 9pm.

Just upgraded to a larger 5 ton unit, does a great job cooling the house. will run for 30-45 minutes and bring the temp down and shut off. Inside temp is set at 76-77, while the outside time is 102 today.

I'm getting tired of going out and manually turning the mister on and then off. I WFH, and my office is on the outside wall so I can hear this unit kick on and kick off.

Here is what I want:

I want to put an electrical shutoff valve in line at the faucet. When the unit turns on, I want it to open and when the unit shuts off, I want the valve to close.

I think this is what I need, but not sure how to wire it in.

Informed suggestions are appreciated.

Here is the valve I am considering: https://www.amazon.com/Normally-Ele...pa-0-8mpa/dp/B0C2YWHBZ6/?tag=atomicindus08-20

or this: https://www.amazon.com/BACOENG-AC110V-Normally-Electric-Solenoid/dp/B00OCDXM4M/?tag=atomicindus08-20

I know I am a redneck, so don't flame me about my engineering.

 

[mike93lx]

If the 5 ton is cooling well, why use the misters? Does it save enough on power to offset the water cost plus all this equipment? Is the water chemistry right to not have any detrimental impact on the coil?

 

[MrFreeze]

If the 5 ton is cooling well, why use the misters? Does it save enough on power to offset the water cost plus all this equipment? Is the water chemistry right to not have any detrimental impact on the coil?

This is an excellent point. Condensers and fluid coolers that are designed to run wet require chemically treated and monitored water. Otherwise you will get a lot of mineral deposits built up on the coil (water evaporates on the surface, but things like calcium and iron stay behind) and heat transfer will suffer. I would try to keep the misting to a minimum. I have seen condensers plugged solid with mineral deposits when run without proper water treatment. A lot will depend on the water chemistry in your particular area.

Good luck,
MrFreeze

 

[KSJeff]

If you want to take out the engineering...

The Original, Patented Cool-n-Save AC Misting Kit

The original Cool-n-Save AC Misting Kit. This is the patented innovation that started a movement in 2007. Winner of the “Green Engineering” from TechAmerica and Harvey Mudd College in 2011. The kit includes everything you need to start saving money on your air conditioning. This is the invention...

coolnsave.com

 

[TWConway]

Good question about the water. I have not given that much thought, but have been running a mister on the old unit for 15+ years and did not notice any build up.

 

[theoldwizard1]

If the 5 ton is cooling well, why use the misters?

Because most cooling calculations are done assuming a 90°F - 95°F outside temp ! When the outside temp is above 100°F very few HVAC systems have "extra" capacity for that !

 

[theoldwizard1]

A water mister that I built out of 1/2 PVC pipe and .7 GPH misting nozzles. I have a total of 6 nozzles surrounding my outside unit.

I would be concerned about minerals (including dissolved iron) in the water. They could build up on the fins.

 

[dcg9381]

Good question about the water. I have not given that much thought, but have been running a mister on the old unit for 15+ years and did not notice any build up.

I'd say that's proof enough you have good water. I'd wager that in "most" places this would not work due to mineral build up. But it works just fine for the OP. I like the science project.

Of those two "pressure switches" the OP pointed out, I'd definitely use the 2nd one.

 

[PFSard]

Good luck with this. If you do decide to go forth with this, I'd be interested in your posting the findings in this thread. Since AZ water is hard, I probably would not try it here.

 

[Bert_]

You want a solenoid valve. Either 240v or, if the transformer can support it, 24v ac.