Cheap Airconditioning With Geothermal Cooling

[flifsh1]

A friend of mine just brought an interesting sort of heat exchanger back with him from a resent trip to China. It looks just like the fan units of a regular wall or ceiling mounted air conditioning unit we see in Asia but it does not use Freon – it uses cold water.

You apparently need a source of cool water that is pumped through the unit. The cool water will absorb heat from the air then return the warmer water either back to its source or wherever you want it to go.

The unit came with no information so we are kind of in the dark on some issues. Our thoughts are to use ground water – so we plan to dig a well for this purpose. Has anyone had any experience with this type of system? We are not sure how cool the water should be to get efficiency with it. Obviously the cooler the better but how cool? The deeper the well theoretically the cooler the water but also the higher the water has to be pumped thus increasing energy costs.

The flow rate of the cooling water will also affect the units efficiency.

My fingers are crossed that we can get it working and provide a very efficient and environmental way to cool the house geothermally without the nasty compressor noise outside the room.

Any input or thoughts?

[backflip]

Using cold water to cool hot air is an old idea, and I can't share your unbridled enthusiasm.

An easier method would be to strap a small Peltier device onto your wrist, neck of temple.

[Naam]

A friend of mine just brought an interesting sort of heat exchanger back with him from a resent trip to China. It looks just like the fan units of a regular wall or ceiling mounted air conditioning unit we see in Asia but it does not use Freon – it uses cold water.

Any input or thoughts?

fan coil units using cold water are used by 99% of big hotels in Thailand (and worldwide). as you don't seem to have too much technical background it might be a problem to get it working. it all depends from what depth you have to pump your water. if the water level is quite low (>30 meters) you need at least a 1HP (0.734kWh) pump which draws the equivalent of a 9,000btu/h aircon unit, i.e. it does not pay considering the cost.

to save energy cost and to prevent the well pump from cycling on/off and to avoid a pressure tank you can build a buffer tank that is filled up by the well pump and from which you feed your fan coil unit with a smaller pumps size consuming less. a problem which still has to be solved is the pump size. for that one needs the data of the unit (resistance of heat exchanger).

to sum it up: the total investment for a single unit is not economical at all. of interest is the setup if you attach at least 4-6 units, cool a medium sized home and save in excess of 50% energy cost. i designed my home to be cooled by fan coil units (available in Thailand) but had to abandon the idea because i was dealing with imbeciles who couldn't even read simple drawings.

anyway, feel free to ask any additional questions or PM me. i'd be glad to be of assistance.

[karlbkk]

A friend of mine just brought an interesting sort of heat exchanger back with him from a resent trip to China. It looks just like the fan units of a regular wall or ceiling mounted air conditioning unit we see in Asia but it does not use Freon – it uses cold water.

You apparently need a source of cool water that is pumped through the unit. The cool water will absorb heat from the air then return the warmer water either back to its source or wherever you want it to go.

The unit came with no information so we are kind of in the dark on some issues. Our thoughts are to use ground water – so we plan to dig a well for this purpose. Has anyone had any experience with this type of system? We are not sure how cool the water should be to get efficiency with it. Obviously the cooler the better but how cool? The deeper the well theoretically the cooler the water but also the higher the water has to be pumped thus increasing energy costs.

The flow rate of the cooling water will also affect the units efficiency.

My fingers are crossed that we can get it working and provide a very efficient and environmental way to cool the house geothermally without the nasty compressor noise outside the room.

Any input or thoughts?

A well is a well you dig down when you hit the water table you have a well,you cannot keep going deeper and the water will be the same temp all the way.

Water coolers was used very big in the UK they are now Banned ther you have to use gas in the uk now but we use an OZONE friendly gas.

Water coold units can collect a bactirea that is a killer and when it kills it kill hundreds.

Karl..

[Naam]

Water coold units can collect a bactirea that is a killer and when it kills it kill hundreds.

Karl..

that's absolute rubbish Karl as the water in the cooling unit inside the house is sealed and nobody is exposed to any bacteria. moreover the water is not recyled. an ample amount of cold fresh water is needed continuously to provide cooling.

[ZZZ]

A friend of mine just brought an interesting sort of heat exchanger back with him from a resent trip to China. It looks just like the fan units of a regular wall or ceiling mounted air conditioning unit we see in Asia but it does not use Freon – it uses cold water.

You apparently need a source of cool water that is pumped through the unit. The cool water will absorb heat from the air then return the warmer water either back to its source or wherever you want it to go.

The unit came with no information so we are kind of in the dark on some issues. Our thoughts are to use ground water – so we plan to dig a well for this purpose. Has anyone had any experience with this type of system? We are not sure how cool the water should be to get efficiency with it. Obviously the cooler the better but how cool? The deeper the well theoretically the cooler the water but also the higher the water has to be pumped thus increasing energy costs.

The flow rate of the cooling water will also affect the units efficiency.

My fingers are crossed that we can get it working and provide a very efficient and environmental way to cool the house geothermally without the nasty compressor noise outside the room.

Any input or thoughts?

The problem is that the deeper you go the hotter the water gets, not cooler. A few meters below the surface the temperature may be a few degrees below the average air temperature but after that the temperature will increase by about 30deg C per kilometer.

So say you get a steady temperature of around 25deg, 2m down. This will only enable you to cool down the air in your house to 25deg if you have no heat radiating in from the outside i.e. perfect insulation. This is assuming the unit you have is a simple heat exchanger, as the heat exchanger will never be cooler than 25 deg. Most likely the insulation is not very good so you will probably only lower the temperature by 1-2 deg during daytime and then actually increase the temperature during night time.

A better way is to use a normal air conditioner but instead of using the normal air cooled condenser unit you bury about 50-100m of copper piping at a depth of about 1m and use this as a condenser. This will increase your performance coefficient from about 2 to about 8, and cut your electricity bill by 75%.

[Naam]

The problem is that the deeper you go the hotter the water gets, not cooler.

i am pumping from a depth of 31m, water temperature a constant 18ºC, i.e. near perfect for fan coil units.

[flifsh1]

The problem is that the deeper you go the hotter the water gets, not cooler.

i am pumping from a depth of 31m, water temperature a constant 18ºC, i.e. near perfect for fan coil units.

Thanks to all for your input, and Dr. Naan the 18 degrees C info – this is exactly what I was trying to find out. I don’t know how much ground water temp. vary in Thailand, I am in C. Rai. I had no idea so many hotels in Thailand were using this system for AC. The cheap places I stay at always have a loud compressor just outside the window.

I had considered pumping into an insulated tank then pumping from there to the heat exchanger with a 12 volt pump that is connected to a regulated solar panel / battery system. The question would then be what flow rate would be required to get maximum efficiency with say 18 C running through the unit?

I was wondering if the bacteria Karl was referring to is from the condensation that could collect in the unit? As well from my research the water temperatures in a water table can vary from the top to the bottom of the table – the lower you go the cooler it becomes within the table.

[Naam]

Thanks to all for your input, and Dr. Naan the 18 degrees C info – this is exactly what I was trying to find out. I don’t know how much ground water temp. vary in Thailand, I am in C. Rai.

1) I had no idea so many hotels in Thailand were using this system for AC. The cheap places I stay at always have a loud compressor just outside the window.

2) I had considered pumping into an insulated tank then pumping from there to the heat exchanger with a 12 volt pump that is connected to a regulated solar panel / battery system. The question would then be what flow rate would be required to get maximum efficiency with say 18 C running through the unit?

3) I was wondering if the bacteria Karl was referring to is from the condensation that could collect in the unit? As well from my research the water temperatures in a water table can vary from the top to the bottom of the table – 4) the lower you go the cooler it becomes within the table.

1) using Freon instead of chilled water for big hotels would mean huge setup cost and maintenance. water piping is cheap and much easier to handle.

2) that's the optimal way to do it but the question still remains what pump size to use. insulating the tank is too much of a hassle. a PVC ground tank will do the job, especially as the water is continuously replaced.

3) Karl mixed the things a bit up because condens water forms on any cooling coil no matter whether water or freon cooled.

4) increased temperature because of drilling depth is negligible. nobody of us has enough money to drill that deep

if you are serious with your project i would like to work with you on it (free of charge!). basis however is to get some technical specifications of the fan coil unit procured in China.

[elkangorito]

The chilled water temperature in commercial chilled water HVAC systems is generally between 6 & 9 degrees Celsius.

A chilled water plant is considerably more expensive to install compared to a DX (direct expansion - uses refrigerant through tubes to cool air) plant but a chilled water plant is considerably more efficient than a DX plant. Chilled water maintenance costs air higher than DX plant maintenance.

Your 'off coil air temp' for a chilled water coil should be between about 15 degrees (& up to about 18 degrees if the duct lenght is kept short).

[Naam]

we are not discussing a chiller Kangorito but simply using well water as cooling media.

[MrSquigle]

The disease discussed is 'legionaires disease' and can be present in water cooling towers on any office, hospital, residential type building that uses this type of cooling, in fact it can be in waterwys and ponds etc also. It usually happens through improper care and treatment though, but certainly happens.

[elkangorito]

A friend of mine just brought an interesting sort of heat exchanger back with him from a resent trip to China. It looks just like the fan units of a regular wall or ceiling mounted air conditioning unit we see in Asia but it does not use Freon – it uses cold water.

You apparently need a source of cool water that is pumped through the unit. The cool water will absorb heat from the air then return the warmer water either back to its source or wherever you want it to go.

The unit came with no information so we are kind of in the dark on some issues. Our thoughts are to use ground water – so we plan to dig a well for this purpose. Has anyone had any experience with this type of system? We are not sure how cool the water should be to get efficiency with it. Obviously the cooler the better but how cool? The deeper the well theoretically the cooler the water but also the higher the water has to be pumped thus increasing energy costs.

The flow rate of the cooling water will also affect the units efficiency.

My fingers are crossed that we can get it working and provide a very efficient and environmental way to cool the house geothermally without the nasty compressor noise outside the room.

Any input or thoughts?

we are not discussing a chiller Kangorito but simply using well water as cooling media.

I'd doubt that 18 degree water pumped through a fan coil will have any noticeable affect on the ambient air temp in Thailand, & lets not forget the heat load. I think if this idea is to be of any use, the water would need to be no warmer than about 12 degrees C.

Interesting concept though.

[autonomous_unit]

Is the original poster talking about an indoor heat exchanger that uses cool water?

Another geothermal system I've read about uses a regular heat-pump with an expanding refrigerant, but instead of exchanging again with an outside refrigerant-air heat exchanger, it exchanges with a larger underground loop of water (or some other solution). It is a closed loop circulating through a pipe that is laid out in trenches to resemble a large radiator, and it can dump heat there during the summer and extract heat in the winter (in colder climates where you want home heating).

This is also supposed to save quite a bit as the air conditioner does less work when it has a more temperate underground heat sink...

[karlbkk]

Water coold units can collect a bactirea that is a killer and when it kills it kill hundreds.

Karl..

that's absolute rubbish Karl as the water in the cooling unit inside the house is sealed and nobody is exposed to any bacteria. moreover the water is not recyled. an ample amount of cold fresh water is needed continuously to provide cooling.

IT is not rubish i can tell you now you cannot use them anymore in the uk becuse of this problem sealed or not the water has to come out somewhere.

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

Karl...

[Naam]

I'd doubt that 18 degree water pumped through a fan coil will have any noticeable affect on the ambient air temp in Thailand, & lets not forget the heat load. I think if this idea is to be of any use, the water would need to be no warmer than about 12 degrees C.

Interesting concept though.

Kangorito, we have built straight water cooled systems (without chillers) in Saudi Arabia (loooong time ago) with water temperatures at the heat exchanger between 24 and 27ºC cooling down factories to 32ºC with ambient temperatures at 42-45ºC.

[Naam]

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

That is NOT what i am saying as the water is not recycled to the well but used to irrigate the garden where mother nature takes care of bacteria (if any).

the "old hack" is used in each and every big hotel worldwide. there is no way to use infinite long refrigerant pipes.

[lopburi3]

The below web site explains normal chiller operation using (gas) type heat exchange systems for those who have mentioned closed water systems - I can say 38F worked well here in Bangkok in my experience. But if water temp got higher cooling capacity suffered greatly (I understand that additional fan coil units would help solve that but at some point you run out of room or perhaps pay more for fans/maintenance than cooling).

http://www.chillersolutions.com/index2.php?page=chiller

[elkangorito]

I'd doubt that 18 degree water pumped through a fan coil will have any noticeable affect on the ambient air temp in Thailand, & lets not forget the heat load. I think if this idea is to be of any use, the water would need to be no warmer than about 12 degrees C.

Interesting concept though.

Kangorito, we have built straight water cooled systems (without chillers) in Saudi Arabia (loooong time ago) with water temperatures at the heat exchanger between 24 and 27ºC cooling down factories to 32ºC with ambient temperatures at 42-45ºC.

No probs Doc...I get what you're saying but what is the humidity in Saudi Arabia? If it is dryer air than in Thailand, then it is already a more comfortable atmosphere in which to be. So, dropping the temp from 42-45 to 32 will 'seem' noticeably cooler.

[elkangorito]

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

That is NOT what i am saying as the water is not recycled to the well but used to irrigate the garden where mother nature takes care of bacteria (if any).

the "old hack" is used in each and every big hotel worldwide. there is no way to use infinite long refrigerant pipes.

I agree with Doc...you're on the wrong track Karl. Are you thinking of evaporative coolers? If so, there is still only a tiny possibility of any bacterial infection if they are used. Or are you saying that pumping water from a well, through sealed pipework, through a sealed fan coil unit & then back into the well, is somehow dangerous?

BTW, Legionella bacteria exists in just about all water & even moist soil. They are harmless if ingested. When the coliform units increase above a certain point, inhaling the bacteria (carried by water droplets/vapour) can cause Pneumonia. The bacteria is killed at about 73 degrees Celsius & is virtually dormant at about 20 degrees C or less.

[Naam]

No probs Doc...I get what you're saying but what is the humidity in Saudi Arabia? If it is dryer air than in Thailand, then it is already a more comfortable atmosphere in which to be. So, dropping the temp from 42-45 to 32 will 'seem' noticeably cooler.

huge variation in humidity in coastal areas (especially Eastern Province) depending on time of the day and wind direction. when the sun is up down to 20%, after sunset up to 95%. and YES you are right. entering a factory building which has a temperature of 32 degrees coming from 45 degrees feels like entering a fridge (for half an hour or so). but for those who work physically in there the difference of 10-15 centigrades provides a big relief.

i am talking of biblical times of course . except for some steel rolling mill, etc. most factories are nowadays fully airconditioned.

[Vansana]

I am planning also to have a geothermal cooling system in my house.

Here is an interesting solution http://www.siamgpi.com/solarpower/solarcooling.html

They are cooling the ceiling and the walls.

It seems there is a need for 2 Boreholes, even i would use the water for irrigation the excess water has to be reinjected into a second well.

[Naam]

I am planning also to have a geothermal cooling system in my house.

Here is an interesting solution http://www.siamgpi.com/solarpower/solarcooling.html

They are cooling the ceiling and the walls.

It seems there is a need for 2 Boreholes, even i would use the water for irrigation the excess water has to be reinjected into a second well.

the company does not mention anything about the condense water problem. would be interesting to know how they solve this problem.

[chownah]

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

That is NOT what i am saying as the water is not recycled to the well but used to irrigate the garden where mother nature takes care of bacteria (if any).

the "old hack" is used in each and every big hotel worldwide. there is no way to use infinite long refrigerant pipes.

I agree with Doc...you're on the wrong track Karl. Are you thinking of evaporative coolers? If so, there is still only a tiny possibility of any bacterial infection if they are used. Or are you saying that pumping water from a well, through sealed pipework, through a sealed fan coil unit & then back into the well, is somehow dangerous?

BTW, Legionella bacteria exists in just about all water & even moist soil. They are harmless if ingested. When the coliform units increase above a certain point, inhaling the bacteria (carried by water droplets/vapour) can cause Pneumonia. The bacteria is killed at about 73 degrees Celsius & is virtually dormant at about 20 degrees C or less.

It is my understanding that the bacteria that causes Legionaire's Disease lives in the water that condenses on the outside of the coils and then is channeled away in a drainage system. It seems that there are enough stagnant pockets of this condensate in some/many/most? fan coil units that sometimes a colony of the bacteria will fluorish. This is just what I have read somewhere...it is not from personal experience in that I am not a doctor, epidemiologist, nor fan coil technician...nor a member of the American Legion.

Chownah

[karlbkk]

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

That is NOT what i am saying as the water is not recycled to the well but used to irrigate the garden where mother nature takes care of bacteria (if any).

the "old hack" is used in each and every big hotel worldwide. there is no way to use infinite long refrigerant pipes.

once the bacteria is in the water it can get airbourne thats when you get the problems.

as it is now most of the Hotels, offices etc are now changeing to gas fill i know this that is part what i do here in Thailand and did in the uk and to take out an old water system in the UK you need a lot of kit for you and to put round the area of work

Karl...

[karlbkk]

So what you are saying is dig a well pump the water up use it and tip it back in so you are putting it back to the water table then smart move not....

Water cooled systems are old hack what is wrong with gas filled why try to go back in time to stuff that is not much good.

That is NOT what i am saying as the water is not recycled to the well but used to irrigate the garden where mother nature takes care of bacteria (if any).

the "old hack" is used in each and every big hotel worldwide. there is no way to use infinite long refrigerant pipes.

I agree with Doc...you're on the wrong track Karl. Are you thinking of evaporative coolers? If so, there is still only a tiny possibility of any bacterial infection if they are used. Or are you saying that pumping water from a well, through sealed pipework, through a sealed fan coil unit & then back into the well, is somehow dangerous?

BTW, Legionella bacteria exists in just about all water & even moist soil. They are harmless if ingested. When the coliform units increase above a certain point, inhaling the bacteria (carried by water droplets/vapour) can cause Pneumonia. The bacteria is killed at about 73 degrees Celsius & is virtually dormant at about 20 degrees C or less.

All well and good when the unit is new with new pipe work but you get the problems when it gets old

H&S uk have a dim veiw on this system

karl...

[flifsh1]

I came upon this interesting site of a Canadian University student that uses only a fan with a copper coil zap tied to it with cool water running through the coil. His original water source was from ice water but he later upgraded to using the city water supply which is 15 degrees C. He can vary the flow rate depending on how low he wants to bring the room temperature.

http://www.eng.uwaterloo.ca/~gmilburn/ac/geoff_ac.html

The heat exchanger I originally mentioned is much more sophisticated than this and therefore I would assume more efficient. As to the Legionnaires Disease I will have to look closely as to how the water produced from condensation is dealt with in the unit.

Thanks for all the suggestions and input. When the system is finally installed I will post an update (assuming I have not succumbed to Legionnaires…)

[Naam]

once the bacteria is in the water it can get airbourne

usually i enjoy technical discussions Karl. however i try hard to refrain from discussing the colours and the brush stroke of van Gogh or Rembrandt with a blind person.

[Naam]

fan coil units that sometimes a colony of the bacteria will fluorish.

there is no difference between a water cooled "fan coil unit" and a "normal aircon unit" as far as condense water is concerned. both have formation of water at the heat exchanger which has to be drained.

[chownah]

fan coil units that sometimes a colony of the bacteria will fluorish.

there is no difference between a water cooled "fan coil unit" and a "normal aircon unit" as far as condense water is concerned. both have formation of water at the heat exchanger which has to be drained.

Good point....makes me think that both types of air con units would harbor the bacteria or that the problem is not in the condensate. One point is that in many parts of the world fan coil units are used for both heating and cooling...wonder if this might point to the fan coil to the exclusion of the "normal" air con units...don't know. I googled a bit and found lots of references that mostly more or less said that the exact way that the disease is contracted from mechanical installations in large buildings is not understood. They also mostly indicated that the bacteria likes a warm moist environment which makes cooling units as a source sort of surprising to me.

Chownah