Water condensing ventless air conditioner

[Handlobraesing]

Why doesn't such a thing exist in small size? There are large restaurant refrigeration machines with a domestic water cooled condenser that simply uses water as a medium.

There are also large air conditioners that uses water, but using domestic water as a carrier and dumping it would be prohibitively expensive for something that large, so they evaporate the water and use the latent heat.

A window air conditioner is basically a box with two rooms. The back room contains a air intake/exhaust for condensing unit and the compressor and is kept outside the window. The front room has just the evaporator and the fan.

There are apartments/dormitories prohibiting the use of window air conditioners. Apartments have a water source and some dorm rooms do. Why not a ventless air conditioner that connects to the faucet, reject the heat into the water and down the drain?

Green = water flow
red = hot side
blue = cold side

It could use a few settings depending on the utility rate. If your apartment has free water, but you pay electricity, you incresae water flow to reduce temperature rise in condenser to improve BTU/kWh input. If you pay neither, reduce water flow to save water, but increase water flow when extra BTUs of cooling is needed (lower the condensing coil temperature, the better the performance)

 

[Carabidae]

Isnt the cost associated with just running the compressor regaurdless of the output? Also if it was more efficient, wouldn't it just freeze up the unit because the water in the air would freeze on the unit? Just a guess, don't know much about ac units, just have messed with them here and there.
I'll ask a friend of mine, he's an AC specialist.

Thinking about it though, that would be quite a waste of water too, unless you use it for something else or recycle it.

 

[nerdgineer]

+1 to Carabidae - if you dump the water to dump the heat, you waste a LOT of water. If you dump the heat in the water into something else (the air?) to recycle the water, then you're back where you started - why not use the air to cool the compressor in the first place?

 

[Carabidae]

Guess you could try that to heat up your bath or a tub, don't know how much the water would absorb until there's not longer a gradient though.

Those portable ones don't seem too bad, they just have that exhaust hose that you put on a cracked window, there just not cheap.

 

[Valpo Hawkeye]

What you're talking about is basically an open-loop geothermal system. We install them, but mostly closed loops (in ground). For an open loop (dump) system, you need 1.5 gallons/minute per ton of cooling. Assuming a window-unit-sized A/C, between 12k-18k BTH (1-1.5 tons), you would need between 1.5-2.25 gallons per minute.

 

[Carabidae]

Ha, one hot night =

>540 gallons down the drain.

 

[Valpo Hawkeye]

Ha, one hot night =

>540 gallons down the drain.

Assuming the unit has to run non-stop. There are nights like that, especially if it's an area-cooling unit...

When we put in open-loop systems, the customers usually have to have a variable-speed DCM well pump to keep up with the demand and to avoid frequent cycling of a traditional well pump. One simple way to describe this type of system: $$$

 

[Handlobraesing]

What you're talking about is basically an open-loop geothermal system. We install them, but mostly closed loops (in ground). For an open loop (dump) system, you need 1.5 gallons/minute per ton of cooling. Assuming a window-unit-sized A/C, between 12k-18k BTH (1-1.5 tons), you would need between 1.5-2.25 gallons per minute.

But if your rent includes water....

 

[Valpo Hawkeye]

But if your rent includes water....

IMHO, it would be irresponsible to use this much water, 'free' or otherwise. They do make room A/C's that simply vent the hot air through a 4" dryer-vent-style tube. Same application, but far more practical. We often put these in server rooms when the main system can't keep up. Most times we just dump the 'exhaust' into the attic or a chase of some kind.

 

[Handlobraesing]

+1 to Carabidae - if you dump the water to dump the heat, you waste a LOT of water. If you dump the heat in the water into something else (the air?) to recycle the water, then you're back where you started - why not use the air to cool the compressor in the first place?

That requires a heat exchange with air from a space other than the space you want to cool.

 

[Valpo Hawkeye]

No exchange, simply exhaust. Room air is passed over the condenser coil, then vented elsewhere, whether that's outside, attic, etc.

 

[Handlobraesing]

No exchange, simply exhaust. Room air is passed over the condenser coil, then vented elsewhere, whether that's outside, attic, etc.

Which means you're dumping some cooled air from the room and letting outside air into the room. If you pay both water and electricity, this is understandable.

If you only pay electricity and rent includes water, you want a water flow that keeps the input vs. output water temperature difference to the minimum to maximize refrigeration kcal per electrical kWh.

 

[Valpo Hawkeye]

I don't disagree that a water-cooled condenser is more efficient. My point, and it's only my opinion, is that it's socially irresponsible to dump hundreds of gallons of water a night, especially in urban areas where clean, potable water is at a premium.

 

[gadget_lover]

If you are in a position where your water is included in the rent and you use a system as proposed, your landlord will probably feel you are abusing the system and will either raise the rent or kick you out. The water bill can be quite high if you live in an area like mine where the bill is tiered based on use. The tier is set up to discourage high usage through ever increasing prices.

A similar idea for taking advantage of the "free water" is to install a water turbine. The water flow turns a generator that makes electricity that you can use as needed. It sounds neat but would end up running the rivers dry if it were widespread. It's not "free energy" since the water company has to pump the water to your house and pressurize the lines.

But it's a neat thought.

Daniel

 

[carbine15]

If you have only an exhaust hose expelling hot air out of the room.. wouldn't the room take on a vacuume leading to people exploding or at the very least, the exhaust fan having to work harder and harder? If you crack a window on the other side of the room, wouldn't that defeat the purpose of cooling the room in the first place? A/c units need an intake and an exhaust independent of the room they are cooling or efficiency drops way down. I find a nice mist of water over an air cooled condenser makes that condenser much much cooler and only wastes maybe a gallon / hour.

 

[Valpo Hawkeye]

If you have only an exhaust hose expelling hot air out of the room.. wouldn't the room take on a vacuume leading to people exploding or at the very least, the exhaust fan having to work harder and harder? If you crack a window on the other side of the room, wouldn't that defeat the purpose of cooling the room in the first place? A/c units need an intake and an exhaust independent of the room they are cooling or efficiency drops way down. I find a nice mist of water over an air cooled condenser makes that condenser much much cooler and only wastes maybe a gallon / hour.

Very few rooms/houses are as tight as you suggest. Let's face it, your furnace, water heater, range exhaust and bathroom fans all put your house in a negative pressure. I haven't read of any of my neighbors exploding yet. As for the misting, it does help, but if you drop your head pressure too much, you'll also drop your suction temp and risk freezing your evaporator if you're charge is off even a little.