There's only one reason water piping has changed from copper to plastic - cost, pure and simple. No other good reason.

this great you guys are all wound up

 

so 20 years ago plastic and copper were about the same price

 

maybe because plastic lasts longer

is this thread geo vs. acadia or water source geo vs. dx geo, i guess both are interesting,
I have a question or two about dx , it does make sense that eliminating pumping costs, and using a better heat transfer medium(copper over plastic) would translate into significant operational savings. 1. So why do cop differences seem marginal? 2.what are the cost differences for dx vs water source. 3. anyone know of the longest operating dx system?

The marginal preformance increase is basicly due to the fact a dx system has very roughly 2000 or less sq inches of contact with the ground , to have a feild the same size as a water system would have serious oil return issues , and a plastic feild that size wouldnt last a day
the oldest Earthlinked DX system is currently operating in Jackson, MI installed in 1987
Dont know if its still going but from what I read it was in 07

The installers cost is less with DX what that translates for a cust would depend on the installer

thanks

the cost saving running if any have never been proved

 

as far as costs about the same

 

and to say least controls on the ECR is a little crude

and if I remember right it's 5 lbs of freon for every ton sitting in the ground

Frankly, the unfortunate thing I'm seeing with DX here is that it attracts more guys that don't know geo at all. When approaching geo for the first time the hvac masses are attracted to the system that doesn't require new knowledge or tools. Unfortunately like any record growth area or industry, it is often difficult to seperate the wheat from the chaff. In our region I'm convinced that this has DX headed for trouble.
That it works very well if installed correctly is true in any of the systems I'm trained in. That it is less expensive in our region is only true if you have dealers working for unusually tight margins which makes me suspicious that some are not securing permits or paying sales tax on equipment from out of state.
I've mentioned before that I can buy a water source 4 ton and pay a geo excavator to bring loops to the heat pump and flush (turn-key) for the same price as a 4 ton DX that requires significant extra time and 30+ lbs of refrigerant from me. That's only cheaper if I'm not paying for something else.
Not a criticism of DX, just a comment about our local situation.
Water source includes the benefit of longer reach which in the case of one home I mentioned recently meant we could go horizontal instead of vertical. That DX loops are all the same size means that some will work better than others based on soil conductivity, that water source employs different length loops simply implies a greater level of knowledge of the installer/loop designer (in many cases).
It is clear to me that Clark has extensive knowledge in heat pump technology, I wish the same were true of every DX dealer.
In the interest of the original thread I will reiterate my feeling that advancement in ASHP tech. is very interesting and many consumers will benefit greatly if we can do away with multithousand dollar loop fields down the road.
J

Just to answer a couple of things...

EarthLinked, out of FL, is using Copeland compressors. I don't know what ECR Industries (PA) uses.

Typically, an EarthLinked DX heat pump will be about 20%-30% more efficient than a closed loop water source system. This is because of their superior refrigerant controls. These same controls could be adapted to any R-22 type system (systems that run the same type of pressures) and increase their efficiency. They allow for near zero superheat or subcooling.

With this new tax credit, the sales rep's must be more scrutinizing in their choice of new installers. Their job becomes more difficult. However, I still don't think one little company will affect enough market share to give any water source systems a run for their money. Especially when there's only bad-mouthing and rumors floating around the geothermal arena.

As far as installed cost, it's typically a little less to install it here in our area. Of course, each area is its own animal...

Sorry to have gotten this thread off topic, Joe. I agree that if we can reduce the cost of loops, much more than just 1% of the heating and cooling market will be geothermal.

Clark you certainly owe me no apologies, but my point was Air Source is one to watch right now. I think that it is moving farther North and South than we geo guys care to recognize. We can't claim ourselves to be cutting edge and ignore wider application of these systems.
As always, application is determined job to job. Geo certainly enjoys broader appeal in MI now as it reaches much deeper into the cold weather season without aux. Give me an (proven) 8K$ airsource that comes close (in performance and reliability), however, and I won't be afraid to recommend it.
J

Wow, seems I opened up another can or worms. Yes, there are dealers in Ohio, but not in my area, and the installers in my area, are not dealers. This is one of the issues I have here. Nobody seems to do the entire job. Most of the dealers in my area rely on subcontractors to do the drilling. And those in my area that do the geo-thermal drilling, do not do DX systems.

As for the sustainability of copper in the ground, it was my understanding that some sort of heat conductive grout is used in areas where acidity is an issue. This grout supposedly surrounds the copper tubing, thereby protecting it from both mechanical and chemical damage. I think there is also a coated copper tubing available to protect it from chemical damage.

As for possible freon leakage and contamination issues, again I was under the impression that the refrigerant used was inert and would not damage or contaminate anything if a leak would occur.

As far as being outlawed in MA, I believe one of the first installations of these units was in MA, and MIT was instrumental in getting it off the ground and has done major monitoring of the efficiency of it.

One of my concerns is sulfur. I have some sulfur in my well water and it eats the copper and eventually destroys it. Will it not do the same to copper tubing in the geothermal installation? Will the grout protect them from sulfur? Does the corrosion protection system protect against sulfur?

I'm not a geothermal expert. I'm just a slug who has had an air-to-air heat pump for the last 35 years and would never have another one in this area of Northwestern Ohio. Just when you need them most, they become totally inefficient. I have resorted to a wood burner when it really gets cold. But now I am planning another residence and I don't intend to make the same mistakes again.

I really appreciate all the input. To be honest, I sort of figured my posting would be ignored because that's the reaction I get when I mention DX geothermal to dealers and installers around here.

Thanks to all of you for your input.

Either GSHP system will work well for you, so why not go with the products the local guys have to offer (providing of course their references are good). You don't want to be too far off an installer's beaten track if you need service.

Im a DX guy
being a hvac guy
but sulfer in the ground is cause for concern
might be better suited for water source
cathode protection wouldnt help
grout incasement would but I would be hard pressed to say that it would be worth the risk
man that was hard to type

A year from now I'll be able to give a lot better description of my experience with the Daikin system, but so far I'm pleased with it except for one aspect. Because you can connect multiple indoor units to one outdoor unit I put a 9000 Btuh wall unit in my garage. The outdoor unit is 36k max output. At output demands less than 50% the power input stays pretty constant at it's minimum of about 6000 Btuh. The net result is that when only my garage unit is running, and running at a throttled back level of maybe 6000 Btuh due to air temp being near the set point, my COP is only about 1. That's the same as straight electric resistance heating.

Next winter I will try letting the garage temp fluctuate quite a bit by setting the wall unit to run only a few hours a day, hopefully the same hours the house unit will be running. The idea is to get the wall unit to run at full capacity and bring the COP up to at least 1.5. With the house unit running the COP should range from 3 to 3.5.

What this really makes clear to me is that the best way to bring heat into a house is a two step process, regardless of the heat source. Step one is to extract the heat from either ground or air with the heat pump running at its most efficient performance point, or a gas boiler burning at its most efficient setting, and put that heat into a storage medium that provides surge capacity. Step two is to move the heat from the storage medium into the living space at the same rate as it's being lost through the building envelope. No heat pump will run at its most efficient operating point if it is required to match its current output to the current demand. Water-to-water and air-to-water heat pumps with a storage tank or feeding radiant in a slab are two current approaches that pretty much do this. The old gas hot water boiler with big old cast iron radiators I had in a house I owned near Pittsburgh nearly 40 years ago did this. The colder the weather the hotter the radiators got.

One of these days I'll graph the Daikin data and see just how close to flat its operating efficiency curve is from 50% to 130% of rated load.

With the exception of newer modulating boilers, I wasn't aware of ways in which radiators could be hotter when the weather got colder.
2 and 3 stage systems do most of what you describe and variable flow systems may come closer (Daiken and Earthlinked do this in different ways) but I don't think you can maintain a flat temperature while the weather is in flux, without varied C.O.P. A storage tanks capacity is finite while weather variables are not, and stand by loss (while not significant) will still impact C.O.P. What you describe in your garage, will likely work, but don't try it with mama in your own home.
It does make for confusing reading when new customers compare C.O.P's, but everything is listed with it's peak efficiency (including by the way gas furnaces which at 95% peak might average 88% efficiency).
J

What happened was as the weather got colder and the heat loss increased the cycle time for the wall thermostat increased. With the increased firing time in the boiler the water got warmer. In effect the system was self modulating. That old hot water boiler with the cast iron radiators was in a lot of ways the best heating system I've ever had. The house walls were clay tile construction with no insulation so they were real heat sinks!

This is what I tried to change my message to.

What happened was as the weather got colder and the heat loss increased the cycle time for the wall thermostat increased. The thermostat controlled the firing of the boiler, not the circulation of the water. Pump ran only when the boiler was firing. With the increased firing time in the boiler the water got warmer. In effect the system was self modulating. That old hot water boiler with the cast iron radiators was in a lot of ways the best heating system I've ever had. The house walls were clay tile construction with no insulation so they were real heat sinks!


Moderators,

Please fix the editing capabilities of this forum software. You cannot successfully and properly edit a comment that contains a quote after it has been posted!!!!!

Thanks for bringing this up.  It is really frustrating.

For what it's worth -
http://www.geothermalspecialties.com/17yearsstillrunnin.htm
That's an article about one of the oldest DX systems. Since I saw that article a long time ago, for some reason, I tend to picture that guy when I read Clark's posts for some reason, but it's probably very off the mark.

Where did you come up that??