A/C Condenser Evaporative Cooling Assist

Well... I have an evaporative assist for one of my A/C's and so far it's being a bit of a problem (NOTE it is home made) I plan on an "Advanced Design" but have not yet ordered the part needed. More on that in a bit.

The system I have is a 1/4" plastic line to where I can hook up to it and a Mister nozzle in the top end 1/2 Gallon per hour Nozzle keeps plugging up (I need to go swap out the nozzles and blow it out ... again..)

I've also used a "Flex Mister" (two mister nozzles 1 GPH) In fact that's where I got the nozzle that's clogging.. I have two of 'em one flexible one not.

Click here to see what I'm yammering about.

dclark1946 wrote:
The 1A per 5 deg seemed higher than I would have expected but there it was in Airxcel's website.

What's the a/c specs show.

mine shows 345 more running watts cooling in standard 95F and desert 115F

Not sure I totally follow the thread ... maybe because in my area of the country few/nobody use evaporator cooling. If I understand the concept you introduce water/sponges between air flow to reduce temps ... but that requires a system to manage water into/discharge? Might be a problem for those of us who go to great lengths to mitigate water intrusion in our RV. Might be worth exploring if you lived in part of the country which was very hot/dry all the time ... probably not for me.

Thanks Doug for your input. The 1A per 5 deg seemed higher than I would have expected but there it was in Airxcel's website.

dclark1946 wrote:
I am wondering if any company offers an evaporative cooler designed to reduce RV A/C condenser inlet air temp to assist in 95+ deg temps? I designed such a system (inspired by some mechanical engineers I worked with) for our residential central A/C back in the late 70's when the condensing units had coils only on one side making the design much simpler. I had the system in place during the torrid 1980 TX heat wave when peak temps reached 113 deg. The system functioned as a nearly constant condenser inlet temperature regulator. As the temperature increased during the day the relative humidity decreased and the evaporative cooling delta t increased so for outside ambient air temp of 113 deg the condenser inlet air temp was 85. This reduced compressor hgh side pressure and consequently lowered current draw. Our unit cycled nicely even in those extreme temps.

The main complication for RV A/C applications to me is the condensing air inlet being on both sides of the unit requiring some ducting of the evaporative cooler's output air or maybe an enclosure over the whole unit except for the back for the condenser's air exhaust with a single duct feeding the cooled air to the enclosure. Maybe just block off the side inlets and feed the cooled air into the units cover.

Based on Coleman's Evaluating RV A/C performance document, you would expect compressor current draw to increase 1A over LRA for every 5 deg above 95 and also decrease the same amount for every 5 deg below 95 so there would be benefits for reducing power consumption.

I would welcome any thoughts/feedback.

3 years ago at a Jayco Factory training session, the RVP rep brought up that 5 degree figure. Well for the previous 41 years as a TRAINED RV Technician from both Dometic and RVP and the correct figure is 10 degrees. While the rep and I argued the 5 degree in class, I had my smart phone under the table and connected to RVP Technical. THEY confirmed the 10 degree is the correct figure, which made the RVP rep extremely angry. I would bet RVP has not changed to the correct figure for their on line troubleshooting. So, use the 10 degree figure. As I pointed out to that rep, IF I use the 5 degree temp differential when doing a check out under warranty, I could condemn every RVP AC and get RVP to send a new one. BTW, I use the 10 degree figure as of today and the amp draws ARE CORRECT for temp compensated Amp draw. Doug

time2roll wrote:
use the condenser fan to blow the condensate onto the condenser coils for better cooling.

Slinger ring, work great.

valhalla360 wrote:
What exactly are you considering an evaporative cooler? Is it simply a mister that sprays across the condenser or are you thinking of a separate unit (swamp cooler) that then feeds pre-cooled air to the condenser.

Where are you getting the water for the system? The normal water you see dripping off RV air/con units is pure water condensed from the air with no mineral content.

Your typical campground water supply is mineral laden well water. If the excess slowly drips down the side of the unit, it would presumably leave heavy mineral deposits.

In principal reduced power consumption is good but unless you are on a permanent site, electricity is typically included in the site rental, so no savings for the end user.

I am talking about a true evaporative cooler to deal with the issue of keeping water off the condenser coils for the reasons you mention. The system I designed years ago used the old style Aspen wood evaporator cooler pad held by a wood frame with chicken wire to contain the pad and heavy rubber foam weather stripping where it mated to the condenser cabinet in front of the condenser coils. A pvc pipe with small holes drilled at one inch intervals fed by clear vinyl slide on hose attached to an evaporator cooler pump kept the pad wet. The pump sat in a plastic dish pan in a hole in the ground so the top of the pan was level with the top of the condenser concrete pad. Water was collected by a tray made of aluminum flashing and was open at one end to drain into the dish pan so the pump could recirculate the water back to the top of the pad. The dish pan had a water float valve fed by a quarter inch copper water line connected to an outdoor faucet. The pump was wired into one side of the contactor and only ran when the condenser unit was operating.

I had to make one change to the original design adding a cover to the dishpan when I discovered a frog happily perched on top of the float which caused water to flow continuously and overflow.

With respect to power saving I was thinking of those running off generator and at our house when we are prepping our trailer in hot TX Aug. for a trip to the mountains. We run the A/C for several days before leaving to help the RV fridge deal with 98+ deg temp sitting in full sun in our backyard.

In addition based on my research years ago, an A/C's BTU capacity is rated at 95 deg. As the ambient temp goes up above that temp the unit loses capacity when you need it the most. The evaporative cooler keeps you from losing capacity.

I remember installing a few "through the wall" A/C units in a few apartments and these units would use the condenser fan to blow the condensate onto the condenser coils for better cooling. Too bad RV units do not use this old technology to improve efficiency. Otherwise the move to mini-split units will not happen fast enough.

What exactly are you considering an evaporative cooler? Is it simply a mister that sprays across the condenser or are you thinking of a separate unit (swamp cooler) that then feeds pre-cooled air to the condenser.

Where are you getting the water for the system? The normal water you see dripping off RV air/con units is pure water condensed from the air with no mineral content.

Your typical campground water supply is mineral laden well water. If the excess slowly drips down the side of the unit, it would presumably leave heavy mineral deposits.

In principal reduced power consumption is good but unless you are on a permanent site, electricity is typically included in the site rental, so no savings for the end user.