Air conditioner condensing unit shade to reduce heat

[SwampNut]

Bullshit or real?  Seems like it should make a difference.  My two units are in full sun for a few hours of the day, probably until 12-1pm or so.  And if I'm going to try this, buy or build...

 

 

 

Another possible benefit is to help prevent any amount of hot exhaust air from going back into the condenser coils.

 

[Zero Knievel]

I’d be skeptical but you are in Arizona.  The standard “shielding” likely is inadequate.

[SwampNut]

There's no shielding on any such condenser; the coils are exposed to the sun.

[Zero Knievel]

1 hour ago, SwampNut said:

There's no shielding on any such condenser; the coils are exposed to the sun.

 

Mine has it, but in direct sun I would wonder how much it helps by itself.

 

Honestly, the coils are "covered" so the sun shouldn't be directly hitting them.  However, the cover panels are exposed and likely are absorbing a lot of heat...making the incoming air even hotter.

Edited May 20 by Zero Knievel

[DaveK]

Love keeping my shit new.  Spendy, but I have this....

 

Different concept, I know.  Ceramic'd that bitch too. 

 

[ironmike]

Judicious placement of deciduous shade trees can offer the same function, relative to the location & environment, potentially at less cost, and be more aesthetically pleasing.

Edited May 21 by ironmike
correction . . .

[SwampNut]

7 minutes ago, ironmike said:

Judicious placement of deciduous shade trees can offer the same function, relative to the location & environment, at much less cost, and be more aesthetically pleasing.

 

Much more cost, in both buying a large enough tree, then running irrigation to it, using water for it, and cleaning up the mess it causes.  There's also simply not enough room for it.  The ACs are located in a walkway along the side of the house.

 

[ptxyz]

i've thought about this for this for a recently installed heat pump that gets afternoon sun but, all the online information i've seen implies it's only going to save a few percent, if done correctly.

 

https://neccoopenergy.com/does-shade-improve-air-conditioner-efficiency-debunking-a-common-myth/

 

 

Why Shading Isn’t Effective

The main reason shading the condenser unit doesn’t help much is that air conditioners work by moving large amounts of air through their cooling coils and fins. It’s the temperature of this air, not the casing of the unit, that impacts efficiency. Even if the unit is in the shade, the air being drawn in is still the same temperature as the surrounding environment.

A typical 3-ton air conditioner condenser moves around 170,000 cubic feet of air per hour. This massive volume of air means that any small temperature drop from shading the unit itself has a very limited impact on overall efficiency.

A similar study by the Kuwait Institute for Scientific Research in 2010 found that shading only improves efficiency by up to 1%.

 

[Zero Knievel]

Maybe it would help older, basic units, but our Trane’s outside condenser is HUGE.  This makes it more efficient as a heat pump, and the coils are well shielded by the outside casing.  Keep in mind that our heat pump must be over 10 years old as it was installed well before my dad passed in 2017.

[DaveK]

A blast from the past…..

 

Adding “HVAC expert” to the resume. 
 

😊

[SwampNut]

This condenser is bigger than the one it replaced, but the coils are still on the outside surface, and I've never seen a design that is not like that.  It's around ten years old, it was a high (but not highest) efficiency unit for the time.  Also everything is relative to location; Virginia sun and AZ sun cannot be compared.  It's also not a heat pump, we have natural gas heat which is cheap and efficient.

 

Another wild thing that I think should help, maybe more than shade, is to mist the condenser coils or provide swamp-cooled air.  Obviously, if I hose down the coils, the inside temps drop a lot.  Would a mist do the same?  Would it offset the cost of water, filters (can't spray minerals on the coil), etc?

 

[Zero Knievel]

If you arranged a system that captures used water and returns it to the sprayer in a closed loop.  Otherwise you’re wasting water in a desert town.

[SwampNut]

29 minutes ago, Zero Knievel said:

If you arranged a system that captures used water and returns it to the sprayer in a closed loop.  Otherwise you’re wasting water in a desert town.

 

...You...don't understand how evaporative cooling works???

 

[Zero Knievel]

I do…so what you propose is a massive waste of municipal water.

[SwampNut]

Yes, of course, like any swamp cooler.  I'd guess there are over a million in AZ.  And datacenter cooling.  And hotel cooling.

 

 

[ptxyz]

if you can spare the water, a mist system would appear to offer efficiency gains, with some tradeoffs;

 

https://coolnsave.com/products/the-original-patented-cool-n-save-ac-misting-kit?variant=40427855577137&country=US&currency=USD&utm_medium=product_sync&utm_source=google&utm_content=sag_organic&utm_campaign=sag_organic&srsltid=AfmBOorkiPhzHrZWlUoigwrmSlRy7XFjCQ54QzP3CvTATUIKQQgixj4C7ZI&com_cvv=8fb3d522dc163aeadb66e08cd7450cbbdddc64c6cf2e8891f6d48747c6d56d2c

 

as you might expect, wet metal corrodes...

 

now that i think about it, the outdoor unit's dumping heat, like a car radiator.  it's the surrounding air temperature, much more than the unit's surface temperature.

 

i'm probably not going to bother with an awning over my heat pump's outdoor unit.  as it's already under the eve, it's shaded until late afternoon.

[SwampNut]

17 hours ago, ptxyz said:

as you might expect, wet metal corrodes...

 

 

The important bits are alloy, the steel is just the shell.  Also I bet it would dry during the "off" cycles, it's so damn dry here.  We have extremely hard water though, and can't easily get our softened water out there.  Well, I could plumb it off the fire suppression system, but then there's always a chance of setting off the alarm.  I suspect we'd use at least one filter per year, maybe more.

 

[SwampNut]

Cool‑n‑Save and similar AC misting kits can improve condenser efficiency and reduce power use in hot, dry climates, but real‑world tests and pro reviews show results are highly variable and long‑term downsides (mineral buildup, maintenance, questionable ROI) are common concerns. Many HVAC techs are skeptical and see them as marginal at best or potentially harmful to equipment over time if water quality is poor.reddityoutubethe-gadgeteer+3

Below is a rundown of what independent reviewers, users, and HVAC pros have found about Cool‑n‑Save specifically and other condenser‑misting systems (Mistbox, DIY misters, generic Amazon kits).

How Cool‑n‑Save Is Supposed to Work

Cool‑n‑Save mounts on top of your outdoor condenser and uses the condenser fan airflow to lift a paddle and open a valve, spraying a fine mist around the unit while it runs. The company claims the flash‑evaporating mist can drop the ambient temperature around the unit by roughly 20–30°F in hot conditions, reducing head pressure and power draw.youtubecoolnsave

Their basic kit includes three misting arms, brass nozzles, a water treatment cartridge to limit calcium/mineral particles, and about 20 ft of tubing, with claimed savings of up to 30% on AC energy use in the right conditions (hot and relatively dry climates).coolnsave+1

Positive Reviews and “It Works” Tests

Some early adopters and DIY testers report obvious performance and bill improvements:

• A YouTube user who tracked bills over two months in hot, humid Florida reported the Cool‑n‑Save system reduced his electric bill by about 30–35 dollars per month and dropped the air temperature around his condenser by around 20°F.youtube

• Marketing and influencer content (including TikTok and YouTube) frequently repeat the “up to 30% savings” claim and show visibly reduced compressor amperage or cooler supply‑air temps when misting around the condenser.tiktokyoutube+1

Independent tests of similar misting systems (and even simple hose‑spray tests) show that pre‑cooling air across the condenser coil can reduce compressor wattage and improve EER in the short term, especially in dry climates like Arizona or Nevada.the-gadgeteeryoutubesense

Critical Reviews and HVAC Pro Opinions

HVAC pros on forums and Reddit threads are much more negative:

• On r/hvacadvice, techs describe these condenser misting add‑ons as “pretty close to a scam” and point out they simply spray water on your coils, which can shorten coil life or reduce efficiency over time due to mineral deposits.reddit+1

• A heating/AC discussion on HeatingHelp notes that while you may get some efficiency gain, you should not expect dramatic bill cuts, and any savings might be offset by long‑term maintenance or early equipment replacement.heatinghelp+1

• A separate Reddit thread on condenser misting warns that even with filters, dissolved minerals in water will eventually precipitate and clog or coat the condenser fins, degrading heat transfer and negating any efficiency benefit.reddit

There are also skeptical YouTube reviews directly calling out Cool‑n‑Save and similar products as a poor value, especially in commercial contexts where proper condenser sizing and maintenance are preferred over add‑on gadgets.youtube+1

Other Products Like Cool‑n‑Save

Several products target the same “pre‑cool the condenser with mist” idea:

• Mistbox: A smart misting system that straps to the condenser, ties into Wi‑Fi, and uses sensors plus weather data to time the mist cycles. A detailed review at The Gadgeteer found installation straightforward and confirmed cooler supply air and some power savings, but emphasized that the full “up to 30% savings” only makes sense in hot, dry climates and that the device itself is expensive (around 399 dollars) and uses a subscription model.cnet+1

• Generic Amazon/retail misting rings or “AC mister” kits: These are simple tubing/nozzle rings that zip‑tie around the condenser and run whenever you open a valve. Reviews are mixed: some users see cooler air and modest utility savings; others complain that nozzles clog quickly, parts are flimsy, and the system fails after a short time.tools.woot

• DIY misters: Some energy‑monitoring users simulate these systems using a garden hose and power‑monitor devices like Sense, measuring compressor draw with and without misting; they do observe reduced power draw during misting, but long‑term usage raises the same mineral and corrosion concerns.sense+1

Overall, systems that monitor water usage and timing (like Mistbox) tend to perform better and waste less water, but they cost significantly more up front and still share the same water‑quality risks.the-gadgeteer+1

Realistic Energy Savings and Costs

Across user tests and reviews of Cool‑n‑Save and Mistbox‑type products:

• Short‑term efficiency: Users often see lower head pressure, cooler supply air, and reduced compressor wattage when misting is active.youtube+1the-gadgeteer

• Bill savings: Depending on local rates and climate, some users report 10–30% summer bill reductions, while others see little to no measurable change after accounting for weather variability and normal usage differences.arstechnicayoutubethe-gadgeteer

• Water usage and cost: Mistbox’s review measured around 0.12 gallons per minute (about 7.2 gallons per hour) for its misting, equating to “pennies a day” in most locations, though high water‑rate areas will feel it more. Simple kits like Cool‑n‑Save will use water at similar orders of magnitude, depending on nozzle count and orifice size.youtubethe-gadgeteer

When you factor in product cost (around 120 dollars for Cool‑n‑Save, up to 399 dollars for Mistbox) plus filter replacement and potential maintenance, payback is very climate‑dependent; hot, dry markets with high kWh costs are where these systems can make financial sense.coolnsave+2

Longevity, Maintenance, and Risk

The biggest long‑term red flag repeatedly mentioned by pros is mineral deposition:

• Mineral deposits: Even with inline filters, dissolved minerals in potable water will precipitate onto the condenser fins as the mist evaporates, creating an insulating layer that reduces heat transfer and can block airflow. This effect is worse in hard‑water areas (a specific “Hard Water Warning” exists on Cool‑n‑Save’s site).heatinghelp+2

• Nozzle clogging and cheap hardware: User reviews of generic misters complain about nozzles clogging within minutes to days as minerals and debris collect, and some note undersized or cheaply built valves.houzz+1

• Manufacturer countermeasures: Cool‑n‑Save includes a “Cool Release” water treatment filter and strongly recommends seasonal cartridge replacement to limit mineral particulates, which adds recurring cost. Mistbox includes modes like “water saver” to reduce water usage and still maintain most of the benefit.the-gadgeteer+1

HVAC techs point out that condensers are designed to withstand rain, but constant fine mist right at the coil plus mineral content is a different scenario and can drive more frequent cleaning and possibly earlier coil replacement.heatinghelp+1

When These Systems Make Sense (For You in AZ)

Given you are in Peoria, AZ and comfortable with DIY:

• Climate advantage: Hot, very dry conditions are ideal for this tech; evaporative cooling is highly effective there, so you are in one of the best climates for getting actual benefits.sense+1

• Water hardness: Much of Arizona has hard to very hard water, so mineral control (filters, softener, or using RO/treated water) is critical to avoid fouling the condenser.reddit+1

• Engineering mindset: With your background, you could plausibly DIY a system with:

  • A dedicated filtered supply (or softened/RO water).

  • Easily serviceable nozzles and seasonal coil‑cleaning routines.

  • Instrumentation (power monitor on the condenser circuit, temp probes) to validate whether you’re actually saving anything.

If you treat it as an experiment and are willing to maintain it, a Cool‑n‑Save‑style system or a DIY variant could be interesting for you; if you’re expecting guaranteed big savings with no downside, the evidence suggests that’s optimistic.arstechnicayoutubethe-gadgeteer

Practical Recommendation

• If you buy Cool‑n‑Save or similar:

  • Plan on seasonal coil cleaning and filter/nozzle maintenance.

  • Test objectively: log kWh and runtime with and without misting during similar weather.

  • Watch for visible white mineral crust on fins; if you see buildup, reassess.

• Alternative upgrades that HVAC pros favor:

  • Ensure condenser is clean and unobstructed.

  • Shade the condenser without blocking airflow.

  • Check charge and airflow to make sure the system is running to spec.

  • Consider efficiency upgrades (higher SEER, variable‑speed) when you’re due for replacement.

Would you like a step‑by‑step test plan (using a cheap smart meter or Sense/Emporia‑type monitor) to quantify whether a misting system actually saves you money on your specific AC setup?

[SwampNut]

[SwampNut]

Looks like the measured water usage for these is around 7 gallons per hour of runtime, so basically nothing.  However as I look at the chemistry, we have one of two problems.  Filtered (not RO) water will still have dissolved solids to build up and must be cleaned.  RO water would slowly remove the alloy fin coating and eventually eat the copper coils.  I can't come up with a clean and safe alternative, but also can't find good data on using softened water.

 

[SwampNut]

Quote

Cool-N-Save, Inc. (“Company,” “we,” “us,” or “our”) does not sell the Product to INDIVIDUALS who represent that they use well water or are located in any of the following areas: Arizona, Southern and Central Nevada, High Desert, or Palm Springs, California and surrounding areas.

 

 

So "Arizona" has such hard water that they won't sell it here, and our specific location is 2x the average for the state.