Making an OLD A/C unit more efficient. How much will this help?

I have a VERY old self contained (mobile home unit) A/C unit on the roof of my house in Florida. When I bought the home it had no A/C and this one was given to me. Its been working fine for 4 years.

Being the shade tree engineer that I am, I thought I could make it more efficient by installing a weeper (dripper) hose around the top of the condenser coil and let cool (as cool as florida water gets) water flow down the Condenser coil while the unit is running.

How I did it: Simply placed a few feet of weeper hose around the top of the cond coil, connected it to an old 24 volt irrigation valve, hooked the valve up to the Yellow and Common so the water only runs when the compressor runs.

The Results: First off the water here is cheap but I do collect the water that runs off to water the plants. The inside are temp at the register runs about one degree cooler when the water is on compared to turning off my little invention.

It sure seems to me that the A/C does not run as much, or maybe its just me hoping I came up with a great idea.

So the question is...... any idea how much i may save by this little invention? Was this a good idea?

I didnt pay a dime for the material, the extra water is used for the plants and I cant hurt the A/C unit for it was junk to start with.

Any ideas, savings or thoughts are very much welcome.

Thanks,
Dan

goinggulfing;
Am not an A/C guy but I see one problem with your system.
If you have a high mineral content in your water you will have a scale buildup on the Condenser which will be difficult to remove.

Hi goinggulfing

It is a good idea, ur invention theory is based on an enhancement in performance of condenser heat transfer causing an increase in condenser subcooling. I think the inlet refrigerant to ur condenser from the top and the exit from the bottom and as u pour a water over the condenser top to relieve the condenser from the desuperheating load and the condenser is free to produce efficient subcooled refrigerant and in turn an improvement in refrigeration effect and colder supply air. So the idea is beneficial, and to reap more benefits, i suggest to make the pouring of water in spraying shape by using a spraying nozzle and try to distribute the spraying nozzles to cover up the top surface and i u can sprinkle a water in air path before entering the condenser it will be fine i.e. firm a plate has a width bigger than the condenser top width and make small tapered holes "nozzles" some nozzles sprinkle the water over the air and the other sprinkle the water over the top condenser. The water spraying over the incoming air will make this air to be cooled further and then the water spraying over the condenser top will cool the refrigerant as u made but by increasing surface contact rea by water droplets. these will be fine if the Florida weather is not very humid and on the same time condenser fan is not forced draft but it is induced draft. After that try to clean the condenser periodically to avoid sticking of dusts "fouling" due to the clogged water droplets and protect ur condenser from rust by painting it to avoid rust propagation as NH3LVR mentioned

evapourative condencer! Can net lowewr head pressure = less power draw =better condencing = slightly better capacity, not new at all but handy thing to be don!

This is a solution widely used (unfortunately) in Italy.

Final result the scale thickness on the coils after one year of operation is not allowing the proper heat exchange and with or withouth water you aren't able to condensate.

At least you should use demineralized water (but I suppose the solution is becoming less economic and you cannot use the water for plants).

or usae a descaler every couple months.

Thank you all for your input.

Yes the scale buildup will be a problem but maybe not as bad expected for the soaker hose is made of a foam rubber and might filter some of the scale before it leaves the hose. I will clean the coil much more often then I normally would.

I do know this is not a new idea for I have worked on water cooled condensers before. I just thought this cheap little idea on an old unit was pretty ingenious.

What I should do is borrow some gauges and very good Amp meter and run the test again to see what the savings are. Its been years since I have worked on refers and that is why I came to this forum to get replies from the hi tech guys or girls.

After the scale ruins the condenser I have plans to submerge the condenser in the canal in the back yard but that will cost some money.

I did start the project with misters spraying on the condenser but with it being on the roof, the wind kept blowing the water all over the place and thats when I went for the soaker hose that allows the water to run down the condenser and stay there.

Thanks again,
Dan

Quote:

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Originally Posted by goinggulfing

I thought I could make it more efficient by installing a weeper (dripper) hose around the top of the condenser coil and let cool (as cool as florida water gets) water flow down the Condenser coil while the unit is running. - Dan

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INFO: Chap I know (in-house maint) was looking after 4 large chillers that were sometimes not quite up to the peak load, and he would hose them down in the mid afternoon to hold the (room) temperatures down in the computer rooms, etc. Increased the duty for him, though the scaling/descaling is an important downside.

If you choke up or block some of the incoming air on to the condenser , you will save money as the power consumption of the unit will drop off , as it has less air to move.

Nothing new, we were doing this 20-30 years ago on undersized refrigeration rack condensers that were poorly engineered. Scale was a problem, but when you have a customer or an engineer who does not want to own up their mistakes, you do what you gotta do. We put these homeade sprayers on timers to run only at peak heat periods of the day. Funny what we do sometimes.

Not a new idea in transport industry also ..... operators at stores, abattoirs or distrib centres etc where 'warmish loads' going into warm truck boxes without sufficient precooling time, or just any unit struggling in high ambient tropics, have often times sprayed cool water with the garden hose on 404a unit condensers.

A citybus operator ( frquent door openings, heavy pax loading and lots of latent load) had idea to collect the condensate water from the interior and spray it over the condenser using small windscreen washer type pump and jets!!! , rather than draining it to the ground. You will see many citybus in humid tropics just streaming water onto the ground. In milder ambients you would not have this constant volume of 'water' coming down the drains.

Furthermore ....

Another guy in Indonesia had idea to prevent wilting and moisture loss for fresh veg and fruit trucks to retain that same evap condensate water from the produce and 'mist' the interior of truck , again using automotive windscreen wiper pump & nozzle assemblies!

Another idea is to use " utrasound " devices to mist that drain water - like you can buy in those gift or novelty shops - those fogging bowls that people use as conversation pieces.

Many interesting ideas from aroud the world ....

regards
T-P

My window type Fujitsu, in his outer tray, collect condensate from indor and condenser fan blades constantly splash that condensate on condenser. Little bit noisy, but when outdoor temperature here reach 41°C, he cools my entire apartment without any sign of lack of capacity.
I would never exchange that piece of old machinery with new super, hyper or whatever split type air conditioner.
It is ingenious simplicity and I always sad: why make tings complicated when they could be simple.

I hear you there nike123, I never want to replace my simple cyclic defrost fridge with any of these horrible electronic ones. More things to wrong, and unlike commercial grade stuff, refrigerators are made on the cheap and are likely to not live long outside the 2 year warranty.

Just I note above the water cooling, One site I go to won't uprade their old gear and they run a sprinkler on them.
One day I did a test, of course the pressures drop on discharge and suction, but also the suction temp was 4-6K warmer with the sprinker on.
I am guessing that was caused by overcondensing and excess flash gas in the liquid line.
But the other funny thing was evap air off dropped 2 degrees.

Hi Goinggulfing(golfing) what,s your handicap?
I tell stories, London summer 1976 computer room controlling three London boroughs.Cooling by ten five ton Arkla Servel gas fired chillers (ammonia)
Ambient (from memory) 97o/f This was the warmest recorded period in the UK i think it lasted three to four weeks 90o/f +/-.The temperature in the computer room was creeping up an early warning temperature alarm had activated.All ten chillers were flat out I, then decided to spray the condensing coils with a fire hose , eventually the temperature in the space started falling i was on the roof for about two hours , with the heat from the chillers. i decided to strip down to my underpants directed the fire hose towards the heavens sat under it to cool down.

It was then that i decided to become self employed.
So in answer to your question spraying the coils solved that particular problem,reducing head pressure = lower cost? +increased duty.
The Arkla Servel units Were made in Acron Ohio USA
A question often asked in the HVAC industry"are you sure you sure you have done this kind of work before"?
Grump:D:D:D

Quote:

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Originally Posted by fridg

If you choke up or block some of the incoming air on to the condenser , you will save money as the power consumption of the unit will drop off , as it has less air to move.

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That's a joke, right?

Hi Neighbor :)

Quote:

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Originally Posted by goinggulfing

Yes the scale buildup will be a problem but maybe not as bad expected for the soaker hose is made of a foam rubber and might filter some of the scale before it leaves the hose. I will clean the coil much more often then I normally would.

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You might use the condensate drain water from your A/C evaporator. It is distilled water and will cause less scale buildup... and you won't need a shutoff valve.

Quote:

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Originally Posted by Gary

Hi Neighbor :)



You might use the condensate drain water from your A/C evaporator. It is distilled water and will cause less scale buildup... and you won't need a shutoff valve.

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errrr ahem ! cough cough ..... exxxxxcuse me, Mr 10% here is collecting royalties for this idea! I have faith in the honour code among Fridgies! ;)
Covered for static as well as transport a/c .....

Swiss bank a/c details to follow .....

Seriously, you may need small pump and devise a float level switch - you may not always have sufficient water inthe drip pan to run pump continuously :)

:D Yuk Yuk :D

regards
T-P

Quote:

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Originally Posted by thermo prince

errrr ahem ! cough cough ..... exxxxxcuse me, Mr 10% here is collecting royalties for this idea! I have faith in the honour code among Fridgies! ;)
Covered for static as well as transport a/c .....

Swiss bank a/c details to follow .....

Seriously, you may need small pump and devise a float level switch - you may not always have sufficient water inthe drip pan to run pump continuously :)

:D Yuk Yuk :D

regards
T-P

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It's called a condensate drain pump... sold everywhere... used for pumping uphill. :)

Gary - here's a question for you and some of the other system design -experienced people out there.

Which is the most clever and useful way to utilize this potential resource but otherwise waste chilled condensate water coming from evap to "improve" high side efficiencies , before we allow it drain to ground... and why !

Do we ...

A) Spray it over the condenser fins / cond inlet air stream to improve performance there , during the condensation stage

or

B) Drip it off the liquid line ( or run it through a simple contra flow tube -in -tube heat exchanger that we fabricate) to effectively precool / further subcool liquid refrigerant en route to the tx valve.

Further, in case B) do we 'perform' the heat exchange before receiver tank or after ? and why ? Which is better .....

all ideas welcome :)
T-P

PS. I am aware of proprietary condensate pumps but not all sectors of HVACR use them - incl Transport.
As I said yesterday, in transport scenario a simple method is to get a 12VDC /24VDC windscreen washer pump from automobile breakers yard.

I've seen a common theme among the commercial fridges here will rout the condensate to a basin where they run the discharge line through to "de-superheat" the discharge be for going into the condenser to boil it off as it where.

In domestics they route it to a dish on top of the compressor to help cool it off or follow the commercial side of small scale fridges (Light commercial?)and route it to a dish with the discharge line running through.

those are the most common themes here that I have seen to follow a good patern, and for A/Cs the usual flinger on the condenser prop