Misting the home a/c condenser

[sleddriver]

Originally Posted By: Schmoe
better, but not as efficient. If I'm going to up my water bill, then I want the biggest bang for the buck.

You're missing the main point: When water evaporates, it absorbs a tremendous amount of heat. Why? Because it changes phases. To get the 'biggest bang for [your] buck', you want a water mist so it'll readily evaporate. This is the most efficient use.

 

[sleddriver]

Originally Posted By: Kestas
Some 10 or 20 years ago I remember reading an engineering journal, where - even though the area is scarce of water - they were considering spraying water on the roofs of buildings in the desert Southwest, to ease the energy requirements of air conditioning.

The drier the climate, the better it works thus swamp coolers.

I too read some of those engineering reports done in Tx. I figured I'd experiment on my own by watering my roof and taking attic measurements at periodic intervals. Water is cheaper than electricity by far.

What a great invention water is! Necessary for life AND a great coolant!

 

[PandaBear]

My main concern is mineral deposit. If I mist the water just enough so it evaporate at the inlet of the AC, will it be just as good as if I mist it enough so that the coil will be wet but most of the water is evaporated? My gut feeling tell me I would probably get the most bang for the buck if I mist it enough so there will be water running off the coil yet most of the water is evaporated.

Will spraying water on the tile roof be damaging to the house? I'm kind of concern about water getting into the insulation.

 

[stockrex]

Panda, the evaps and reduces air temp
Some mist will get on the fins or coils but mineral deposit is possible. They have wash to get it spotless.

 

[Kestas]

Update: The weather broke, so I took apart the furnace to look at the evaporator coils. This is what I saw after 22 years of neglect. Both sides looked the same. No wonder my a/c couldn't keep up!

I spent Friday evening cleaning it. I'm hoping this'll help out with winter heating efficiency as well.

 

[The_Jeff]

what is that stuff? cellulose? Never ending wasp nest?

 

[sleddriver]

Wow....

Blocked evap coil = no airflow.

Not cleaned in 22 yrs?? Imagine what your engine would look like if you didn't change the oil for 22 yrs! My coils are cleaned & inspected once a year. You might have to use a foaming coil cleaner to get it shiny again. And to do that, you'll have to remove the coil as you can't use the acid stuff indoors due to fumes. Which means you'll have to get an A/C contractor to do it.

Many people are under the mistaken impression that just because you change your A/C air filter every month/3 mos. that your coil will never get dirty.

 

[sleddriver]

Originally Posted By: PandaBear
My main concern is mineral deposit. If I mist the water just enough so it evaporate at the inlet of the AC, will it be just as good as if I mist it enough so that the coil will be wet but most of the water is evaporated? My gut feeling tell me I would probably get the most bang for the buck if I mist it enough so there will be water running off the coil yet most of the water is evaporated.

Will spraying water on the tile roof be damaging to the house? I'm kind of concern about water getting into the insulation.

You're wise to be concerned about mineral deposits from hard water. As the crust builds up, it'll restrict airflow through the coil, lowering its efficiency and ability to reject heat. I used softened water so deposits weren't a problem.

How could spraying water on your roof be damaging? What about rainfall?

 

[Kestas]

Originally Posted By: sleddriver
You might have to use a foaming coil cleaner to get it shiny again.

After cleaning with a vacuum and brush attachment, I inspected the coils for any impacted material using a mirror and backlight through the fins. Everything has been removed and the air can now flow freely. I just have to wait for hot weather.

 

[Drew99GT]

Now that you cleaned it and it's working good, the heat wave won't return!

 

[PostalBound]

If your A coil looked that bad, I bet your blower (squirrel cage) fan is clogged up too. I just had to replace my 24 year old blower motor (bearings went out) and was amazed at how dirty the blower fan was. Cleaned each fin with hot soapy water and tooth brush. It easily doubled the air volume output throughout the house.

 

[sleddriver]

Originally Posted By: PostalBound
If your A coil looked that bad, I bet your blower (squirrel cage) fan is clogged up too. I just had to replace my 24 year old blower motor (bearings went out) and was amazed at how dirty the blower fan was. Cleaned each fin with hot soapy water and tooth brush. It easily doubled the air volume output throughout the house.

+1 When the little vanes on the blower wheel fill up, the effectiveness really drops.

 

[3311]

I installed a UV light on mine abbot 4 years ago and the evap coils are shiny ever year when I clean out the system.

 

[Schmoe]

Originally Posted By: sleddriver
Originally Posted By: Schmoe
better, but not as efficient. If I'm going to up my water bill, then I want the biggest bang for the buck.

You're missing the main point: When water evaporates, it absorbs a tremendous amount of heat. Why? Because it changes phases. To get the 'biggest bang for [your] buck', you want a water mist so it'll readily evaporate. This is the most efficient use.


I realize that, but when the water coming off of the hose is 125F, just how much heat is coming off the condenser with the sun hitting it and while it's running???? I don't think there would be much benefit.

 

[sleddriver]

Originally Posted By: Schmoe
Originally Posted By: sleddriver
Originally Posted By: Schmoe
better, but not as efficient. If I'm going to up my water bill, then I want the biggest bang for the buck.

You're missing the main point: When water evaporates, it absorbs a tremendous amount of heat. Why? Because it changes phases. To get the 'biggest bang for [your] buck', you want a water mist so it'll readily evaporate. This is the most efficient use.


I realize that, but when the water coming off of the hose is 125F, just how much heat is coming off the condenser with the sun hitting it and while it's running???? I don't think there would be much benefit.


Your first sentence doesn't make sense as the later is independent of the former. Furthermore, why is your condenser exposed to the Sun? It should be shaded, particularly living in Ok, during the Summer. That's the first step.

Your response indicates you don't understand thermodynamics. OK. Your body does though: We're designed to sweat to cool us off. Ever been wet on a windy day and felt chilled? How about standing in front of a fan when you're hot & sweaty? The water evaporating off your skin absorbs a tremendous amount of heat as it changes phases, as I stated earlier. It even happens when the Sun is out and it's hot outside. Swamp coolers work off of this same principle.

If you mist 125°F water, it'll rapidly cool down. You can also keep your 50' hose out of the Sun to start with!

If you flood a condensor with water, you'll block the airflow through it. Not a good idea. Instead, you want to mist it with a fine spray. Enough to wet it, but not flood it.

Here is an interesting thermo-fact about water:
It takes as much energy to melt a block of ice as it does to raise the temp of the same amount of liquid from 32°F to 176°F! Further, that melted water will still be at only 32°F!
All that energy you poured into it, didn't raise the temp of the water at all, it only changed the phase from solid to liquid. Lookup sensible heat and latent heat.

There's more benefit than you realize.

 

[Spazdog]

Originally Posted By: JimPghPA
You could shut down unused zones during hot days, such as bed rooms, as long as you remember to bring them back on about an hour before use.


That's an awesome idea unless the unused zones are right next to the thermostat.

It'll be 10° hotter in the hallway where the thermostat than in the living room if I leave those doors shut.

We still have the original compressor unit installed in 1986. A Janitrol. It's probably like a SEER9 unit. I could probably save a couple hundred bucks a year by changing it but it works still. Works well. It's out in direct sunlight. No water for the condenser.

I do think A/C units up north are quite a bit undersized and may need the extra help. My brother-in-law in Cincinnati's compressor is half the size of ours. Not only overall but the in condenser area. It's tiny. His house is probably nearly 3X the size of ours if you include the finished basement.