Instructables

If I mist my condenser while it help cool my house?


Lets say I put a mister on my condenser outside, and when the air conditioning comes on it sprays water mist on the condenser. The idea would be:
as the water evaporates on the coil it will remove more heat from the unit and it wont run so much.

It strikes me that if sub-cooling is such a great improvement, it makes a lot of sense to get your setup adjusted so it doesn't freeze out. We sub cool some of our micro refrigeration systems, and it works very well.
pschoggens10 months ago
they sell these systems online and I had planned building my own little mist tower around my condenser until I read this blog in it's entirety and learned of some good points. Ca+ built up from the water thus reducing the ability to exchange heat from tap water. If using distilled water, rain water, captured condensate, the PH being off causing corrosion of the condenser coil and rotting away of the metal thus reducing the ability to exchange heat. Building a shade over the unit so it is cool when it starts then seemed logical but the reading referrers to the ability to cool the incoming air with a massive shade as being the most effective. I actually placed my hand on the condenser after it had been running for a few minutes and was surprised to find it was cool on a hot day. Now days I focus on shading my walls from the sun to decrease the heat exchange to the house, thus making my AC more efficient.
:P
pschoggens10 months ago
Glad I found this blog as I too have been thinking along the lines of improving the condenser function by cooling the high side, but I was looking to use condensate or distilled water and swamp cooler medium and building a plenum chamber to allow the AC unit to suck precooled air. The condensate from the AC unit sweetened with distilled would eliminate the mineral build up, the swamp cooler medium would help reduce radiant heat from the sun. My only hold up was designing the water delivery as to which pump and spray nozzle to use and how to power it so it would run only when the condenser fan was on. After all the reading, I feel this concept could create more expense than it would save. Any after thoughts welcome.
:P
Blofish (author)  pschoggens10 months ago
@ pschoggens

Im not sure what you mean by creating more expense. I think you have a pretty good ideal as how to do it.
an example I have about extra cooling... I was told I shouldnt put my deep freezer outdoors during the winter that it needed an amount of heat to take the heat away. Ive had my freezer outdoors in winter for the last 7 years and it was 3 years old when I got it and it works just fine. It does what I wanted and expected it to do. Safety sallies, silly willies, and doomsday saying, but I dont know if they tried and failed and gave up, or just trusted the word of somebody they respected as to be an expert in saying so. It wont hurt anything to try. Nothing is accomplished if it isnt tested and proven to be a fail. I make logical and informed decision based on ALL research and safety practices.
Blofish (author) 4 years ago
godfish wrote this on another instructable... I've been an UA, Local 250 Union HVAC&R Service technician for 20 years, and you are right that it would make scene to cool the hotter line coming from the condenser outside, however Air conditioning systems work on the Pressure Temperature relationship, Cooling the hotter line is called sub-cooling and does make a systems efficiency go up, WAY WAY up. and if you whir to over cool the line too much your indoor coil would make only ICE, blocking the air flow and costing you lots of money in loss of efficiency. SO if we throw the T&P out of whack by over cooling the line, OR like I've seen many times on residential calls people hook up water hoses to spray water on the condenser outside, all that happens is you cost your self more money on your electric bill. The best thing to do is have your A/C unit serviced by an honest company, change your filter when you should and keep the whole system clean, that will save you the most money. Or better yet just turn it off, A/C is a luxury and not a necessity. And YES I work in PALM SPRINGS So Cal, where it gets 121 in the summer, if I can work out in the heat, you can sit in your home without A/C. ;P
Blofish (author)  Blofish4 years ago
My after thoughts after reading posting and thinking about this is... what about interment use of cooling it off? Say if I misted my condenser for 2 minutes it would freeze the evaporator... what if I misted it for 1 minute on and 2 minutes off.. Something is better than nothing, right? I thought I read some where there is a ice sensor on the evaporator to shut the compressor off in the event of icing and turn it on again when it thawed. ( a temperature sensor to sense 0 degrees (C) held 1 mm off a rung in the coil ) besides how hard could it be to make a sensor to detect ice... As far as mineral build-up regular cleaning would be in order... I really think were on to something here, besides where there is a will there is a way...
andy19174 years ago
I have a question steming off this question. I can agree that constant mist fo water would in fact turn it into chiller with all the calcium buildups that follow with it. My question is what if you would simply catch the hotline as you call it and simply install a 100 ft of line in a coil and balance your gas out . We actually wondered what if you burried a 100 ft of line in a coile directly beside the condensor unit. allow the ground to cool it on its on. just a thought
NachoMahma4 years ago
. It sounds like a great idea, doesn't it? Unfortunately, it doesn't work very well once you get off the drawing board. :(
. As Re-design points out, most units are not designed to work in a wet environment and, more importantly, if you have any mineral content in the water, it will build up on the coils as the water evaporates. Think stalactites/stalagmites in fast-forward.
. There is also the problem of galvanic action - coils are usually Al or Cu and most of the other parts are ferrous. Unless you are using distilled water, you're gonna have problems.
. What about pH control?
.
. I like frollard's idea of putting a heat exchanger in a pond or creek (although this may have undesirable environmental consequences).
My ultimate goal is to have entirely solar/geothermal/heat pump heating and cooling in my eventual house. Geo to act as a thermal battery, and then to add or subtract heat from it -- depending on the ambient enthalpy -- I'll use a heat pump to get more in/out as needed. We live in a climate here that spans from -40 to +40 winter to summer, so saving up energy from one season for use in the next has been proven viable. Only trouble is the existing sites don't actively pump heat in/out, they do it passively. A compressor system can run at efficiencies 400% better than just thermal conductance alone :D
Re-design4 years ago
It will help your a/c work less or more efficiently in most cases. But there are several drawbacks. A/c units are waterproof but may not be designed to have a continual mist of water blown into the condenser. If the water has any mineral of salt content then that will eventually build up on the cond. coils and you will loose efficiency. There are products made which are made to do exactly what you are describing . They monitor the unit and only mist when the unit is running.
I wanted to build exactly one of these -- I wonder how much energy it takes to run the high pressure mister... (most are run from a pressure washer pump through a pinhole). Long story short, pretty much anything you can do to raise the heat-capacity of the air on the condenser (even humid air, not 'wet' air) would help. I was tempted to make a heat exchanger that ran some of our pond water (when we had a pond) around the 'hot' line from the ac compressor.
Your idea of using pond water to cool things down is basically what geothermal hvac systems do. Lots more details and problems to address though.
I think its awesome, and ironic that cooling the system makes it mathematically less efficient "at doing the job of using air to cool the condenser" -- yet more efficient overall.
Blofish (author)  frollard4 years ago
Im still trying to figure out how to use our lake for cooling. I was going to make an exchanger for some cooling also, but I (we) have to consider how to do it as environmentally friendly as possible. NO anti freeze. Brine maybe. where should the pump be place (before or after) the evaporator. Its not just about accomplishing something but accomplishing it correctly. In another words many 'FAIL SAFES' Reminds me of my first machine tool program, did it 17 rungs. then it dawned on me 'safety', by the time I added all the safety routines to it, it grow to over 90 rungs!