AC Heat exchanger with ground, avoid external defrost ? can be done ? should work ?

[bmironb]

Hi,

I have an AC sistem with inverter, it's working great on heating untill outside temperature drops below +3 degrees C, down from there external unit is starting to froze too often, i have a lot of defrost cycles, which reduces the yield considerably, in these condition inside i have only a maxim of +21, +22 Celsius(when is setted to +25), wich is not good.(in my country we have an average of -3 C, outside, with with minimum of -8 C)

I've got an ideea from someone that says it should work 100%.
All i have to do is to build a heat exchanger with the ground, in these way: heated refrigerant goes inside from outside unit in one pipe, and from another pipe refrigerant come back outside, this pipe shoult be cutted and taken into the ground at 1,5 m down(coil circulation), in there should be a coil with two rows (a maximum of 8-9 meeters of consumed pipe in total), these should be enough in order not to freeze the external unit coil.In ground at 1,5 meeters i should have +10...+14 Celsius, and like i will have a heat exchanger with the ground and also an electric energy saver.

A second iddea is exactly as the first, only the coil that is in the gound will also be introduced through another pipe, between those pipes i wil have antifreeze liquid recirculated with a small pump, in order to prevent excessive cooling and from there external radiator froze.(this iddea should be like a precautionary measure if the first will not work)

Perhaps the idea is uncalled.

Thanks, please excuse me if I posted in the wrong place, but i'm new in this forum, but I wanted to appeal to professionals that in my country lacks.

[jpsmith1cm]

What you've essentially described is a geothermal or ground source heat pump.

http://en.wikipedia.org/wiki/Geothermal_heat_pump

I don't think that your specifics will work too well, as it tends to require more underground piping than a few meters, but the concept is valid.

[bmironb]

Yes, but instead of water in pipes, will be refrigerant from AC, i know that concept is valid, but the measurements for pipes and ground depth will be questioned and enough to not freeze.I'm wondering if someone did or tried what i said above... ? because with water is another deal....

Thanks

[jpsmith1cm]

Yes, but instead of water in pipes, will be refrigerant from AC, i know that concept is valid, but the measurements for pipes and ground depth will be questioned and enough to not freeze.I'm wondering if someone did or tried what i said above... ? because with water is another deal....

Thanks

I've heard of similar systems.

Myself, I'd be concerned about corrosion of the piping due to soil conditions.

Leak searching would be a BEAR!!!! Not a practical system, IMO.

[5thRoot]

http://en.wikipedia.org/wiki/Direct_...rmal_heat_pump

Your not the first to think of it. In fact the original geothermal heat pumps were direct exchange. And trust someone who works on them frequently, it requires way more engineering than you have so far.

[bmironb]

HI,

Yes my ideea is with direct exchange, but with at least of 20 meeters of pipe, copper, which does not rust.
A second one can be made with plates exchanger wich is not direct, in this case pipes from the ground will be made from plastic and filled with water(recirculated), but here i will have a much consumed power with recirculation pump, maybe a maxim of 200w, this also is good, but here i will have to invest more.
I remain the first idea directly, but I concern regarding the length of copper pipe after calculations would have a total of 25-30 meters, 20 on ground and another 5 meters ouside(wall height).Also in ground copper pipes will be drilling down in 20 meters, or or ditch 20 meters long and 1.5 meters deep.With this length of pipes i will have to fill sistem with a freon excess, but still my ac can function with such a great length (20m-25m) ? if not i will stay in the second version using water in plastic/pvc pipes and exchanger plates.

Thanks

[5thRoot]

Your thinking too much, the cost of this modification will be so high that it wont make financial sense. If you want to get a more efficient system, start from the beginning with a system that is designed to do what you want. Trying to adapt a machine to do what you want is not a good idea.

[jtrammel]

Your thinking too much, the cost of this modification will be so high that it wont make financial sense. If you want to get a more efficient system, start from the beginning with a system that is designed to do what you want. Trying to adapt a machine to do what you want is not a good idea.

X2, especially being a heat pump it will take many calculations and procedures to get the correct amount of piping for it to work properly in both heating and cooling them throw in variable speed compressor and you have to account for keeping it above freezing in heat pump mode from ~30-120% capacity.

[54regcab]

Installing the ground loop is a large part of the cost of installing a geothermal unit. If you are willing to pay the cost of installing the ground loop, just install a geothermal system. Geothermal systems DO work excellent, you're on the right track, just going about it the wrong way...