Posted By geome on 06 Mar 2010 09:46 AM
tinoue, don't leave us hanging, what happened with your system?

Posted By 183eej on 06 Mar 2010 11:03 AM
Something being tested in Texas is a commissioned installation based on actual system performance rather than a prescriptive approach such as Energy Star or LEED.  Just because the AHRI label says 16 SEER, doesn't mean it performs at that level after it is installed. 

An independent system performance verification before release of final payment to the installer, I think, would go a long way towards ensuring customers get what they contracted for.  Money is the language of business and, at the end of the day, that is what the installer really wants more than anything else.

Commissioning would be the final step of the installation before the last payment is made by the customer. 

I wouldn't expect the things you mentioned to be a surprise a year or so down the road though.  Proper sizing of the equipment in accordance with ASHRAE's Manual J should avoid discovering years later that the the ground was freezing or over saturated with heat, which is the primary concern in Texas where I live.

We use Elite, which has a very good Manual J software tool called RHVAC to help accumulate all the features in a home that impacts the heating and cooling load in accordance with Manual J.  All these features are very well documented by the application either by manually inputing the features such as orientation of the home, room sizes, insulation type and R-values, etc. or using Elite's drawing board tool and selecting all the features with a mouse.  And it takes all this information and puts it in context of the home's physical location. 

Mechanical engineers, specializing in geothermal in this area, use Elite's commercial cousin called CHVAC to compile the same story for commercial installs.  RHVAC and CHVAC both links with Elite's Energy Audit tool that is used to compare the financial performance of several systems factoring in tax credits, fuel prices, energy inflation assumptions, etc. 

We used it to compare the projected performance of my Earthlinked system to a ClimateMaster system, an American Standard heat pump and a 13 SEER AC with a natural gas furnace.  It was very helpful and hA proven to be uncannilly accurate.  It projected my Earthlinked system would cost about $56/month to operate at 12 cents per kwh for electricity.  It's averaging $63/month and I am paying 14 centS per kwh.

In context of this message thread, however, it was only uncannily accurate because the installer that I used followed Earthlinked's recommended installation procedure and I had the system performance verified by an independent commissioning agent before I wrote the final check. 

Posted By joe.ami on 07 Mar 2010 10:17 AM
... we heated 3800 SF somewhere (Don't know location) for about
$275.00 in electricity. Don't know if that included other household
consumption. Don't know the heat loss. Do know it's 7 tons.

Posted By 183eej on 06 Mar 2010 11:03 AM 

An independent system performance verification before release of final payment to the installer, I think, would go a long way towards ensuring customers get what they contracted for.  

Posted By tinoue on 09 Mar 2010 10:46 AM
We'd be looking at one visit on initial startup to get initial operational parameters
and perform duct testing and at least one visit after summer or winter ...

Geothermal systems cost a lot of money and its simply prudent business to independently verify performance of something so expensive. 

Posted By jonr on 11 Mar 2011 10:22 AM
Why isn't freeze/thaw air space an equal problem with plastic loops?

Posted By joe.ami on 07 Mar 2010 10:17 AM
OK, according to the other half we heated 3800 SF somewhere (Don't know location) for about $275.00 in electricity. Don't know if that included other household consumption. Don't know the heat loss.
Do know it's 7 tons.
A guy in Texas might have a $50 heating bill but someone in the midwest A'int gonna.
Might not be high, but we still have not been given enough information to know.
Would the OP like to dig up the heat loss and volunteer closest major city? Also we need to know if the $275 included the rest of the house's electrical use.
I suggest we dig up these things before we dig up ground loops or chase wiring around.
j

• We know electrical usage - 2883.  While we DON'T know if it includes household energy use, but from experience with older homes including my own 1908 Queen Anne Colonial - balloon construction, DX Systems - with 3.5 tons down and 3.0 tons up, 2883 is a logical geo only usage for the size/age home.
• We know stated performance of Earthlinked equipment:  3.6 COP
  
• Based on electrical use data, system(s) generated 35.5 MM BTU's 

Posted By John-eli on 11 Mar 2011 09:44 AM
Hello tinoue,

1) on the surface it seems like Earthlinked is a better way to go, except now I'm reading about issues of soil freeze-thaw-freeze cycles around the copper pipes, causing air space around them, and huge drops in efficiency. 

2) The winters rarely go below 0 degrees, but are often in the teens for days at a time, and the summers are very humid, rarely over 100, but often 80-90. 

3) specifically if an Earthlinked system would work, or if you think we'd have to suppliment it with a backup systemthanks very much,
John-E

Posted By trister on 22 Feb 2010 10:45 AM
Just an update. Does anyone know what the temperature should be coming out of supply vents. I would consider the temperature to be somewhat warm at the best. Additionally, the air volume appears to be weak. It took 2 days to balance air flow for the heating and came back and set up the ac flow.