Pros and Cons of Water Chillers vs. Minisplits/AC

[ttystikk]

:) Waste water is perfect for underfloor heating.

...and this is why I love my water chiller so much; not only does just 2 tons of capacity cool well over 8kW of lights, but the waste heat warms my house all winter. It's just warm air, so I don't need to build a new house with pipes under the floor to take advantage of it.

Clearly, this is all headed in the direction of heat pumps and geothermal heating at a fast clip; this may be my next home climate control system!

 

[Racker]

It does the job for me. This one cools 24x600watt with open reflectors. Don't know how many tons that is....

 

[ttystikk]

It does the job for me. This one cools 24x600watt with open reflectors. Don't know how many tons that is....

24x600= 14,400 watts.
There are AC experts littered all over this site, but my seat of the pants guess is something like 6 or 8 tons of cooling. If it's pouring off 60 gallons per hour of 120 degree water it has to be moving some serious heat!

How much to buy one? Do they sell them in the States?

I was only kidding a little about my hot tub- if the water is that hot, there's no reason it couldn't be used for a hot tub. My little puddle is only 330 gallons; using the numbers you mentioned above, that's only 5.5 hours of continuous cooling...

 

[Racker]

Actually the water the unit uses is about 2 gallons every minute when you use open water to drain like i do. (well) Good thing is that it's only using water when cooling is required. The power consumption is 3100watts @ 400volts. (3 phase+neutral) In the states there is no such thing as 400volts but i know there is a special model for the US marked.

There is a model that cools 15000watts (the one on the picture), a model that cools 10000watts, 6000watts and the smallest one cools 3500watts. Water use is different for all models and adjustable. (less water = less cooling....more water is more cooling) It's also possible to use it in a closed system with a pump. (swimming pool, lake, river,) or with a chiller that can cool the water down 41grF. For example 86grF in> 95grF out >86grF in etc etc (Delta-T=41grF). Dutch garden supplys distibute it in US. Ask them for price. I don't know, i'm not a retailer or something.

Hope i make sense....(not my main language:))

 

[fishwhistle]

racker,how much are the units?

 

[Racker]

Dutch garden supplys distibute it in US. Ask them for price. I don't know, i'm not a retailer or something.

 

[ttystikk]

3100 watts divided by 240 volts is 13 amps. That would be the power consumption rate equivalent of the unit you describe.

2gal/min = 8.5 litres/minute while it's in operation. Is that correct? This has my interest because hot water is useful all over the house, there is certainly no need to just pour it down the drain!

Why not take the waste water this thing generates and return it directly to the hot water tank? In Europe, I understand that tankless water heaters are the norm, but in the States most people have sizeable tanks, on the order of 35 to 65 gallons and even larger- many new homes are actually built with multiple hot water tanks so they can fill the huge jacuzzi tubs in their master bathrooms!

 

[instantkarma]

To answer your question about how altitude affects AC, consider that the working fluid for an AC unit is the air you're trying to cool. The denser that air- with humidity, air mass or both- the more efficiently it will operate. High altitude hurts AC efficiency because of low air density, therefore less thermal mass for the AC unit to cool at any given moment, and therefore a loss in effective efficiency. The fact that you're running your minisplit in a sealed room environment is to your benefit and actually increases thermal mass due to higher humidity, that is a good point.

Your water chiller faces the exact same drawback as an AC in this regard. The condenser is still air cooled!

 

[Racker]

3100 watts divided by 240 volts is 13 amps.

In Europe, I understand that tankless water heaters are the norm

The european version is 400volt, 3 phase. I don't know what voltage the US model is....

In europe we use both heaters, the hot water that runs trough your house heats up the tapwater. In areas where there is no natural gas they use hot water tanks that heat up with electricity.

The hot water from the unit can als be used in an other growroom when you grow 12/12 on/off. A heat exchanger tha is used to warm the other growroom when lights are off. (in colder areas)

 

[ttystikk]

Your water chiller faces the exact same drawback as an AC in this regard. The condenser is still air cooled!

If that were true, then water chillers wouldn't enjoy a 30% efficiency advantage over AC. Yet, they do.

 

[instantkarma]

If that were true, then water chillers wouldn't enjoy a 30% efficiency advantage over AC. Yet, they do.

The only part of the process that is more efficient on the water chiller is the evaporator coil removing heat from water rather than air which will obviously be more efficient. The catch is though you are running that cold water through an icebox or air handler which has to remove heat from the air the same way an AC evap coil would. So the heat is still being absorbed from the room through an air cooled coil, and is being exhausted via an air cooled condenser. I don't see how that could possibly be more efficient.

 

[ttystikk]

The only part of the process that is more efficient on the water chiller is the evaporator coil removing heat from water rather than air which will obviously be more efficient. The catch is though you are running that cold water through an icebox or air handler which has to remove heat from the air the same way an AC evap coil would. So the heat is still being absorbed from the room through an air cooled coil, and is being exhausted via an air cooled condenser. I don't see how that could possibly be more efficient.

It's more efficient because water is a far better medium for heat exchange than air. It's even a bit better when mixed with glycol, which is the main reason why it's in your car radiator.

Speaking of examples of how water has better heat transfer efficiency than air, that's why your car HAS a radiator; aircooled engines can't produce as much power (specific output, or horsepower per liter of displacement) as liquid cooled engines can because air can't transfer the excess heat away fast enough.

You make an interesting point about the air to water heat exchangers in water cooled air handlers and 'Ice Boxes'- but you have it backwards. The very reason they work so well is due to the fact that they have water running through them! In addition, it's much easier and again more efficient to have waterlines going from the cooling plant to where the cooling is needed.