Our latest geo job.

geodean.....just curious....how wide/long is that trench?

12' wide x 150' long

The first picture reminds me of train tracks. I have expect to see a train arriving at the train station any minute now. :)

 

 

what is the heat load on that project?

Is there such a difference in soil from one side of the house to the other or did they haul in the reddish dirt? Any idea of the thermal conductivity at the level of the slinkies? And how will you backfill..bed the slinkies with special fill or just put the original stuff back in? Did the backhoe get a workout..looks like pretty hard dirt?

This is a 9 ton heat pump system. The dark band of dirt is the original soil, before the backfill around the house was done. We used the native soil for back fill. The TC is probably around .75. It was pretty hard dirt.

Thanks for sharing this.  Interesting to learn how a horizontal closed-loop system is done.

Looks like it doesn't require the high-priced I'm sure drilling rig equipment to install, but at the expense of needing a lot of land area.  In an urban area like mine, it's not difficult to find structures that need about 9 tons of cooling, but, it is difficult to find the amount of land area it appears to require.

Best regards,

Bill

geo.......NINE tons???????? How big is that house? It doesn't look that big...

I thought the same thing.

me three!

why such tonnage?

The house is 8900 sq ft .

WOW! Where is the rest of it? It looks like two stories, so it's almost 4500 on one floor? It must stretch out behind the shots you have, or go two stories underground.

I'll take some photos of the house and post them.

(Sigh) Here we have 9 tons for 8900 sf in Utah, yet I received 8 tons for 3400 sf in Texas.  Some here note that their GSHP runs for hours / most of the day to keep up - in my case, my average run time is 10 minutes per cycle, and never breaking out of 1st stage, and with it being below 30° outside at the moment.  (Sigh again.)


Best regards,

Bill

Bill,

What kind of run times did you have during the peak of the cooling season?

Dewayne, thanks for the question.

Looking at my WEL data, July was the highest HVAC KWH consumption month.

For my 3 ton unit:

292 hours runtime
31 days
9.4 hrs/day = 39% 'duty cycle' = 24 min./hr 'cycle time'

For my 5 ton unit:

246 hours runtime
7.9 hrs/day = 33% 'duty cycle' = 20 min./hr 'cycle time'

I did a qualitative look at the data, and as you'd expect, the run time is a little shorter in the mornings, and a little longer in the afternoon / evening.  But, on average, the above looks like a reasonable approximation.

Best regards,

Bill

P.S., the above is all 1st stage only.  My units very rarely go to 2nd stage, due to the amount of capacity I have, due to not getting carried away with too large of tstat set back, and due to tstat programming to react slowly to going to 2nd stage.

Bill ~ I've heard that with shorter cycles that there is more humidity in the home... did you experience this? I'm sure you've written it in one of your posts, but I forgot where you are located.

Ona, I did well this past Summer with indoor RH.

You can see historical indoor RH here: http://welserver.com/WEL0043/EnteringWaterTemperatureDailyAvg.gif (it's the cyan line).

During the Summer, I averaged right around 40%, which we were pleased with.

I believe the excellent indoor RH performance was due to a number of factors:

1. The WaterFurnace Envision GSHP has a huge evaporator coil, enabling a lot of water to be removed.

2. We limited our tstat set back pattern to avoid going into 2nd stage, thus keeping the unit running for longer time periods.

3. We set internal tstat parameters such that the tstat was 'slow' to go to 2nd stage, again maximizing unit run time.

4. We never ran with 'fan only' on.

Thus, the average run times I noted above were more than sufficient for excellent indoor RH performance.

Whilte there's constantly a lot of talk about how it's so critical to not oversize, etc., I think item number 1.) above is the most influencing item, and is allowing me to have great indoor RH performance while still appearing to be oversized (maybe considerably).

Best regards,

Bill

geo......let me ask probably a dumb question. So if I build a 3000sf house......I would only have to have a trench 12'w x 50'L....?....If so, this would not take up that much room to build and would be a hellava lot less than drilling.....