I'M INTERESTED IN CONTRACTOR AND END CONSUMER FEED BACK ON EXPERIENCES WITH DIRECT EXCHANGE. I HAVE SYSTEMS IN BUT NOT MUCH LONG TERM FEEDBACK ASIDE FROM FOLKS WHO WANT ME TO SELL IT. I'M AWARE THAT THERE ARE 30 YEAR OLD SYSTEMS OUT THERE STILL PERFORMING AND BELIEVE INSTALLATION TO BE THE LARGEST FACTOR IN LONGEVITY. I ALSO FEEL THAT REMOVING A MIDDLEMAN HAS ADVANTAGES AND APPLICATIONS. I'VE HEARD THE WIVES TALES AND PROBLEMS OF ORIGINAL INSTALLATIONS. I'VE ALSO RESEARCHED TWO OF THE NORTH AMERICAN OFFERINGS AND LIKE WHAT I SEE.
I SAW A RECENT DX DISCUSSION BUT DID NOT GET AS MUCH CUSTOMER OR CONTRACTOR FEED BACK AS I'D LIKE.
JOE

Joe, welcome to the forums. We would all appreciate it if you would not type in ALL CAPS.

Like anything else, properly installed, it's a beautiful system - in fact, they're hard to beat!

DX Advantages

More Reliable

Fewer parts to the system

Does not require a supply and return well.

No well pump, circulation pump or flow center to purchase, install, repair or replace – ever!

No water heat exchanger and associated valving to corrode, freeze, or break.

Less maintenance

Only a sealed refrigeration circuit to maintain.

More Versatile

“DX” systems can be installed in a more confined area than a conventional ground loop system, primarily because the heat exchanger coil is much more efficient at transferring heat to the refrigerant than a plastic earth exchanger. A DX machine requires a vertical ground loop with only a 3-inch diameter borehole drilled to a depth of only100 feet per ton.

Faster install

Minimal impact on landscaping

Less expensive than a properly designed HDPE (plastic) system

About 40% less drilling


What's not to like (in a residential application)?

Ours is just completing its 5th heating season with no breakdowns, failures or resulting service calls.

IMO

SR

SR

I'm almost out of time right now, and will pipe in sometime later some more on this, but when fsq4cw says "Only a sealed refrigeration circuit to maintain." that almost indicates that there is maintenance associated with the loop.

That's not the case that we've seen. There is no loop maintenance required. That's one of the biggest reasons we switched to DX in 2001 from doing water loop systems. We've been doing them for 14 years now...

gotta go.

Tuffluckdriller is correct, being a closed loop, the refrigerant loop on a DX-GSHP requires no maintenance. Pressure however, can be measured and verified.

SR

If there is no pump, how does the refrigent cirrculate thru the system?

“If there is no pump, how does the refrigerant circulate thru the system?”

The compressor, which is ever present in all heat pumps anyway, circulates the refrigerant through a longer circuit – the ground loops. That’s why it’s called ‘DX’, ‘Direct Exchange’ of heat between the ground and the refrigerant. Only the wall of the highly conductive copper tubing separating the earth from the refrigerant. That’s the secret of the high efficiency of DX technology, that and no loop circulating pump or secondary liquid to refrigerant heat exchanger. The ground is your ‘secondary’ Direct (heat) Exchanger!

Personally, I have to say this is brilliant! If you’ve been waiting for a ‘technological break-through’ that will ‘reduce the cost of drilling’ and hence the cost of the ground loops – well folks, this is it!

BTW: It’s not new and it is a proven technology.

SR

OK, I understood that the feon went directly thru the compressor, instead of exchanging the heat/cool thru loops, but I didnt realize the compressor is actually a type of pump in itself, Vapor-compression refrigeration.  Refrigeration may be defined as lowering the temperature of an enclosed space by removing heat from that space and transferring it elsewhere. A device that performs this function may also be called a heat pump. Does anyone know what kind of compressor a heat pump uses? Reciprocating compressor? Rotary screw compressors? Centrifugal compressor? Scroll compressor? or is it a variable depending on the manufacture? What kind of Feon is used in the system and it is enviromentally safe? Is Feon good forever, where it doesnt go stale or lose it's effectiveness where it has to be replaced?

I am building a 7500SF house in Westchester, NY. My builder wants to use a Poly etheline closed loop system and I have another contractor who would like to install a DX copper loop system. The price on the DX system is about 20% less. My builder thinks the copper will corrode and its not a good long term solution. Is this true?

Absolutely not!

Copper comes from the ground. If it naturally corroded in the ground, we would not have it. It simply would not exist.

In the lower 48 states, there is about 5% of the land area where copper would corrode. These areas are acidic (they have a pH below 6.0) Copper will not corrode unless the pH is lower than 6.0. If it is lower than that, you can install EarthLinked's CPS system. This is an IMPRESSED CURRENT cathodic protection that continually bombards the copper loop with electrons, not a sacrificial anode cathodic protection.

Now, I've pointed out why the copper won't corrode from the outside. Let's talk about the inside. Refrigerant is an inert gas. It does not/cannot cause electrolysis. Therefore, it won't corrode from the inside.

With the price of the DX system being 20% lower than the water system, (and most likely the DX is more efficient, too) why wouldn't anyone just choose the DX system? I would, though, strongly suggest EarthLinked to be the better choice in DX. It has the track record of standing behind its design, and performing wonderfully. Time and again we see higher efficiency than what's published. As with all heat pump systems, though, make CERTAIN that it's sized and installed correctly.

In terms of sizing, the original spec was a forced air oil fired boiler with 4 zones AC and heat, 10 tons. Theoretically, should a geo thermal system require the same tonnage or different? The guy that wants to put in the poly etheline system says he need to make the system 17 tons now. The DX guy is staying with the 10 tons. How do I know what's right? Can it be possible that the geo system would require 7 more tons than the conventional system.

What does Earthlinked mean and why is it better?

Yes, that's possible.

As with any heating/cooling system, in order for it to be at its peak efficiency and comfort, you need to start with an accurate load calculation. This calculation needs to accurately take into account the type of insulation, including the R-value. Also, window U-values, direction the house faces, humidity, ceiling height, etc.

From the load calculation, we should be able to tell you how many tons it should be. Or at least have a close guess. I could at least let you know how many tons of Earthlinked DX it would take.