Has anyone used misters around their condensing units?

[Joe Mascitti]

I was wondering, Has anyone used misters around their condensing units? and what results did you see...

Joe

11:00am and already 95 here in Hotlanta!

[michaeln]

The condensing units rust out much faster, good for the a/c dealer, bad for the home owner!!

[sammy37]

Try that in vegas, your coil would be solid concrete bythe end of summer!!

[gevans]

We did it for a temporary fix on a back woods church one time. It works great... for a while. Plugs the condeser coil if it doesn't rust everything out first. Since the church's a/c units were over 20 years old and only used on Sunday mornings, we went for it. The units (Four 5 ton Whirlpools) put out the coldest air ever.
When the weather cooled down somewhat, we shut off the water. Had a 24 volt water valve from Rainbird that energized with the contactor. Probably should have also had a thermostat or pressure switch tied to the condenser.
Used that setup for 3 years, finally put in new systems.

[woody19]

As everyone stated it will corrode the fins and shorten the life of the coil. That is why they make pre-coolers that can be installed in most applications. Haven't seen any in a few years but in Arizona and other desert areas this was pretty common.

[Joe Mascitti]

The new units are supposed to be made of materials that would not rust...if the misters are not directly on the fins, but cooling the air around the units, then that should not be a problem...my old units were 12 years old and did not show any signs of rust...12 years of rain...

So far I have noticed a 5-7 degree drop in coil temp since I have the misters running...it is 103 outside the the upstairs of my home is a confortable 76 degrees...unit is a rudd 3 ton coil with a 2.5 ton condensor....cooling roughly 1900sf.

[Mr Bill]

If anyone knew what this is doing to the pressures and the all around operation of the condenser they would know this misting effect has has no benefit at all, the hotter the condenser the more liquid it will make, if your cooling off the condenser coil with water or mist you will diminish the liquid feed to the metering device, if you do achieve anything it would be a wash, but I see no benefit.

[Shophound]

The new units are supposed to be made of materials that would not rust...if the misters are not directly on the fins, but cooling the air around the units, then that should not be a problem...my old units were 12 years old and did not show any signs of rust...12 years of rain...

So far I have noticed a 5-7 degree drop in coil temp since I have the misters running...it is 103 outside the the upstairs of my home is a confortable 76 degrees...unit is a rudd 3 ton coil with a 2.5 ton condensor....cooling roughly 1900sf.

Those fins WILL clog up in due time, even if the misters are not directed straight at the coil. The condenser fan motor will draw in the mist even if you direct the mist stream away from the coil face. Once this mist hits the hot fins, it evaporates, leaving behind any minerals in the water. True, the cooling effect provided by the mist evaporation is why you're spraying it at the unit to begin with. Leave it run long enough, however, and the minerals being deposited on the fins and tubes will act as an insulator, retarding heat transfer, and actually boosting your operating cost.

This is a losing proposition...the water meter is spinning to provide the misting water, the condenser fins are loading up with mineral deposits, the head pressure (depending on amount of misting taking place) may be substantially reduced to where the pressure difference across the metering device is adversely affected, reducing the refrigerating effect and therefore any hoped for gains via the misting system.

Want more long term bang for your buck? Install radiant barrier against your roof deck. Add attic insulation if necessary. If your windows are old, single pane, aluminum frame jobs, at the very least you'll get a good boost by adding storm windows. Caulk both sets of windows as well. If your a/c supply air grills are in the ceiling, pull them off and caulk between the supply boot and the drywall...allow the caulk to dry before re-installing the grill. If your return air duct system is in any way drawing air into the system from the attic or any other source than the interior of the house, get that taken care of.

Combined, the efforts above far surpass blowing mist at a condenser coil!

[Joe Mascitti]

Thanks for the head's up.. the misters use <1gph...with the coils getting cleaned every spring, won't that keep them in good condition?....Return Air is the same temp as ambient room temp, so that rules out attic air being pulled into the system. Windows are new, double pane....never heard of radient barrier....

Misters have filter to catch minerals...(don't know how good it works?)...

No matter how good a system you have, if the condensor cannot dissapate the heat, the system will not cool...Correct? I am getting an 18 degree temp difference between supply and return air...

thanks!

Joe

[t527ed]

anything strong enough to clean the minerals off the fins will eat them over time.

every one here has told you its not good, stop back in a couple years and let us know if we were right...

[Joe Mascitti]

Point well taken...but what is the difference between that and year round rain on the coils?

Remember, the misters are cooling the air Around the coils, not the coils themselves...

Joe

[Shophound]

Thanks for the head's up.. the misters use <1gph...with the coils getting cleaned every spring, won't that keep them in good condition?....Return Air is the same temp as ambient room temp, so that rules out attic air being pulled into the system. Windows are new, double pane....never heard of radient barrier....

Misters have filter to catch minerals...(don't know how good it works?)...

No matter how good a system you have, if the condensor cannot dissapate the heat, the system will not cool...Correct? I am getting an 18 degree temp difference between supply and return air...

thanks!

Joe

Your system is designed to dissapate heat WITHOUT misters. That is the entire point. You said your systems are new...sure would hate to shoot myself in the foot with that much money sitting out in the yard.

I realize I'm running over your sacred cow, but this is a public forum and this idea, when discussed, needs to have the reality check brought out full bore.

If you are measuring room temperature and then the temperature at the return grill near the unit, that's no indication of heat gain in the return side. You need to measure at the return grill and then right before the air enters the blower, if possible.

[Shophound]

Point well taken...but what is the difference between that and year round rain on the coils?

Remember, the misters are cooling the air Around the coils, not the coils themselves...

Joe

Rain does not leave behind mineral deposits on your coils.