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charles 03-20-13 09:04 PM

cooling with water
I have a wood fired boiler for heat so i have a radiator in my duct work. What i
I want to know is can I pipe cold water up to the radiator and cool the house. I'am thinking of home made water chiller or punching a hole in the ground and using a closed loop. HELP

marx290 03-20-13 10:15 PM

I'm just shooting from the hip here, I've never installed an air conditioner or built a ground source heat pump. The ground temperature in my region was around 60F and it's probably higher in Alabama, so it would you would have to circulate a LOT of water and your blower would have to run constantly to do much cooling. The reason is, although a water radiator would absorb a lot of heat, an air conditioner coil absorbs much more because the liquid in it boils at a cold temperature that can then discharge the heat into the ground loop.

I would think to cool with water would require very cold temperatures, much colder than ground temperature. You might want to think about installing a ground source heat pump depending on the installation costs and soil type in your area.

Piwoslaw 03-21-13 01:36 AM

Welcome to ER, Charles:)

Already having a radiator in the air duct is a good start. Yes, plumbing it to a source of cold water will cool the house, plus it will reduce humidity (good in Alabama). But I can see a few problems you'll need to solve:
  • Since the radiator/duct was installed for heating you will have to find a way to remove condensed moisture,
  • Making a ground loop takes some work,
  • The ground loop will have to be large to soak up the heat. Heat diffuses slowly in the soil, so you will need a large surface area, while it can build up quickly, as Daox found out when trying to dump his house's heat into the basement sump water.

stevehull 03-21-13 05:47 AM


Won't work as your water temp is not cold enough.


cbearden 03-21-13 07:30 PM

a radiator in the air-duct... That sounds very interesting! How possible/costly is this to install in a typical system?

Ryland 03-21-13 08:15 PM

There is a 1,500sf house down the street from me that has a system like this to condition the incoming air for the air to air heat exchanger, it takes care of 100% of their cooling needs in the summer, for that house they have two 350 foot long loops of 3/4" Pex that loop around the house 5 feet down, the two loops allow the fluid to move half as fast as it would if it was a single 700 foot long loop, it's also less work for the pump.
It's not going to be cold air, I think they are getting 55F in the winter and 60F in the summer.

You also have to look at how much energy your blower is using, mine is a single speed blower and draw 600 watts, the pump uses energy too, a few summers ago I ran some tests and found that it used more energy to draw the cool dry air from my basement and blow it around the house then it did to run a window air conditioner because I had to run the furnace fan for so long and the dehumidifier in my basement had to run extra to dry the air.

Daox 04-02-13 03:49 PM

I'd really like to rig up something similar to this. It doesn't have to cool the whole house or even do much cooling really. I would just like something (besides a window shaker) for the ~2 weeks a year that I would like air conditioning. In fact, I did play around with a very simple idea a couple years ago. It worked alright, and I'm sure it could be scaled to work even better with some modifications.

stevehull 04-02-13 06:39 PM


It all depends on your well water temp. In Wisconsin it is likely in the low 40's F. In Alabama, it is likely in the mid 60's F.

In general, you need at least a 20 degree F differential between the dew point and the coil temp in order to get latent moisture out of the air. Otherwise you just swirl around steamy air now saturated with water vapor.

As I posted before, it worked GREAT in Colorado with very, very cold water.

Some open loop geothermal units (ClimateMaster) precool the air with water before it goes to the cold coil. This has the advantage that the air is precooled and the existing cold coil now just has to push the air temp over the latent curve in order to condense the moisture. The result is a cooler coil, more water vapor extracted and more efficiency.

But you need that cold coil and in most open loop geothermal units, the coil can be in the high 30's F. THAT low temp really condenses out the water vapor.


randen 04-03-13 03:45 AM

Here in Canada were the ground loop temp was entering the water to air air-handler at 45 Deg F in the shop with a humid 80 Deg F air temp. The result was that the conditioned air did reduce in temp and humidity but not enough humidity. The air became cool and clamy not so comfortable. As Stevehull mentioned the coil isn't cold enough to reduce the humidity to a comfortable level. I was very suprized as the water was just pouring out. I left it run 24/7 as the power usage was very low.


cbearden 04-03-13 06:45 AM

water storage tank
In thinking about building a water storage tank for my radiant floor, I was wondering which design would be more efficient:
1. insulated wood tank, such as this one:
$2K Solar Space + Water: Storage Tank Design

2. tank that's built into the ground, but lined with the same insulation as used in the above design.

I would think that #2 would end up being more efficient, since the outside surrounding temps would be closer to 60 degrees, rather than lower temps during the winter, as in above-ground design.


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