Water mist help cooling my AC condenser unit

[boilerman856]

Using condensate, I save money in energy, the system is able to handle the load better and there is no issue with any minerals or scale.

I agree Condensate definitely would better than spraying hard ground water on warm aluminum coils. How do you distribute the water over the coil? Do you use a condensate pump?

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[timtanguay]

A lot of window shakers have condensate splashers built onto the condenser fan motor .

[barbar]

Spraying water on to a dry coil is a bad idea, but misting the incoming air is not, and need not cost a lot.
I use the finest cheap domestic irrigation mister nozzle $1.00 (a few depending upon the size), a simple irragation sol valve which is controlled by a simple klixon, either ambient or liquid temp. All the parts for well under $100.
The spray mist is pushed approx 12inch away from the coil, so the whole air flow (low velocity) passes through the mist. The coil does not get wet. any excess water just fall to the ground (along with concentrated TDS and free TDS becomes a invisible dust and passes straight through)
As far as energy saving, 1C drop in SCT (condensing temp) reduces power by approx 3.5%. The system does need to kept in a reasonable equilibrium, hence the kilxon.
A good idea badly applied does not make the idea itself bad, which does seem to be the case here on this thread.

[timtanguay]

Spraying water on to a dry coil is a bad idea, but misting the incoming air is not, and need not cost a lot.
I use the finest cheap domestic irrigation mister nozzle $1.00 (a few depending upon the size), a simple irragation sol valve which is controlled by a simple klixon, either ambient or liquid temp. All the parts for well under $100.
The spray mist is pushed approx 12inch away from the coil, so the whole air flow (low velocity) passes through the mist. The coil does not get wet. any excess water just fall to the ground (along with concentrated TDS and free TDS becomes a invisible dust and passes straight through)
As far as energy saving, 1C drop in SCT (condensing temp) reduces power by approx 3.5%. The system does need to kept in a reasonable equilibrium, hence the kilxon.
A good idea badly applied does not make the idea itself bad, which does seem to be the case here on this thread.

cool. What kind of flow rates are you talking about going through one of those misters? Like 1gph or some small number like that? Depending on how much it runs, it might be expensive...especially if you're on a water meter. Do you have to worry about mineral deposits accumulating on the coil?

A nice side effect is sometimes on really big misters, you get a secondary cooling effect with the water evaporating off the roof. Locally, some walmarts have sprinkler heads set up on their roof. When ambient temps rise sufficiently, they spray down their roof with water.

[barbar]

cool. What kind of flow rates are you talking about going through one of those misters? Like 1gph or some small number like that? Depending on how much it runs, it might be expensive...especially if you're on a water meter. Do you have to worry about mineral deposits accumulating on the coil?

A nice side effect is sometimes on really big misters, you get a secondary cooling effect with the water evaporating off the roof. Locally, some walmarts have sprinkler heads set up on their roof. When ambient temps rise sufficiently, they spray down their roof with water.

If I remember rightly each nozzle is around 5l/h (depending upon the water pressure), we are lucky do not really pay for water, so it is simple which is more expensive water or power and by how much. I have to say generally these are installed because of performance than direct energy saving, and can say a heap on capital cost, if peak load requirement, is sporadic. (It is a very cheap method of capacity control) with the use of EEV, then the operation range is starting to increase (keeping a good equilibrium)

The water does not hit coil, so mineral deposits are not the issue. if you look at the link in a previous post, they are cooling the air not spraying the coil.

Have seem many building spray roofs to reduce heat infiltration. I believe the Germans use a totally wetted roof (for a similar effect)

[coolerguy]

I have done experiment on my home a/c unit.

I went to Home depot and purchase water mist system for your porch they use this thing on desert areas.
So I had bright idea that if i install this guys around my condenser unit and when compressor comes on it turns on mist. i figure it cools condenser faster help compressor work less hard.
but that’s not the case, when mist turns on my supply air temp went up instead i expected temp. should go down.

Is this normal or I'm missing something here, I know theory of how a/c works.
Please someone explain. Thanks.

OMG dont do that

[ironpit]

Robo, are u saying you use condensate? Or are you trying to make a point?

[boilerman856]

How come the minerals or TDs does not plate out when misted into the air flow? Is it just cooling the air before it goes through the condenser? How do you keep the water from hitting the coil?


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[RoBoTeq]

I agree Condensate definitely would better than spraying hard ground water on warm aluminum coils. How do you distribute the water over the coil? Do you use a condensate pump?

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I just run the condensate line to the top of the coil, beneath the top of the unit and let it dump out over the coil. If the unit is running when the condensate pump discharges, the condensate pretty much stays with the coils.

It would certainly be easy enough to distribute the condensate more effectively by plugging the end of the tube and drilling small holes in the condensate tubing where it contacts the top of the coil.

[RoBoTeq]

A lot of window shakers have condensate splashers built onto the condenser fan motor .

Exactly the same concept. I think I have seen the term "slinger" used for the condensing side fan blade having a loop of small slingers on the perimeter of the fan blades to pick up the condensate and sling it into the condensing coil.

This practice did two things; it cooled the condensing coil and it prevented having liquid condensate dripping down the wall of buildings with dozens of through the wall units in it.

[barbar]

How come the minerals or TDs does not plate out when misted into the air flow? Is it just cooling the air before it goes through the condenser? How do you keep the water from hitting the coil?


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Remember that is the air is cooled by vapourization of the water droplets, not sensible cooling. The small droplets evaporate totally, leaving a very small piece of mineral powder, which is dry. The water is pushed in the opposite direction the airflow, so in effect is travelling in a U shape, away from the coil (using water velocity pressure), as the speed drops, the water drops fall, where air movement brings the water back towards the coil. By which tiemit has evaporated, large droplets fall to the ground as air velocity is low and can not over come the weight and gravity. (there droplets has still start to evaporate, so TDS concentration is higher than the original flow. (As a side note, this principle is how they make milk powder, evaporating the water from the milk solids in just a heated air stream, but with a bit more science and expense)
The water does not touch the coil, only lower dry bulb, with high RH% air hits the coil. (if the wind is blowing a few drops may, but not enough to worry about)

[mhamilton247]

Had a friend try it here in phoenix....
Lasted about 2 years...
Then he replaced his "very" corroded condenser... not a good idea!

[RoBoTeq]

Did your friend use water from the condensate? What was the source of the corrosion? The difference between a good idea and a bad one can be the difference in product used.

[mhamilton247]

Not sure... I believe he used city water.
I guess I overlooked the part where you said the water never came in contact with the coil... shouldn't have an issue if that's the case.
The bozo that I know was using a mister system spraying directly onto the coil...
High calcium high evaporation = scaled condenser coil = under deposit corrosion hence 3500$ replacement

[RoBoTeq]

Not sure... I believe he used city water.
I guess I overlooked the part where you said the water never came in contact with the coil... shouldn't have an issue if that's the case.
The bozo that I know was using a mister system spraying directly onto the coil...
High calcium high evaporation = scaled condenser coil = under deposit corrosion hence 3500$ replacement

I have water from my condensate spray directly on the coil. Have been doing this for others for decades, and have never had a problem. No minerals in condensate. Good reason to keep drain pan clean too.

[Random1634]

Yeah never do this. You may get a season or two out of it but after that you better expect to be replacing the condensing unit. Between scale, dirt build up and rust it's not worth it. The coil was designed to be air cooled, if this was feasible everyone would already have it. Everyone is pushing to have the most "green" product around.

[ReferYankee]

Yeah never do this. You may get a season or two out of it but after that you better expect to be replacing the condensing unit. Between scale, dirt build up and rust it's not worth it. The coil was designed to be air cooled, if this was feasible everyone would already have it. Everyone is pushing to have the most "green" product around.

Thus the water source heatpump!

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[Random1634]

Exactly, but I'm thinking the cooling tower may be a bit excessive for the house

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[ReferYankee]

They make the geothermals, and ive seen the water sources piped as heat for pool water

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[Random1634]

Geothermal is the way to go, it's just the most expensive up front. I was just being sarcastic with the last comment.

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