looking at installing a geothermal system .  house has 2500 sq ft.  two story with 2 zones.  calcs done and 4 ton seems to be right.  choices are horizontal or vertical .  which is better and the price to do either is the same.  should it not be cheaper to have a horizontal slinky system over drilling three wells.  i have three quotes  water furnace , climate master and comfortaire.  all are top of the line and similar cop and eer.  the comfortaire is almost 5k cheaper than the wf and the cm is in the middle.  any help would be appreciated.  house is in pennsyltucky more commonly known as land of taxes.

Vertical loops are twice as efficient..........so only half the pipe is installed. Operating cost difference is virtually nil.
Most of us agree installer is more important than brand. Comfortaire is made by Climatemaster.
j

Joe,
Would you please define "twice as efficient" Is that in terms of length of pipe, first cost, operating cost??? . I have projects that have used both vertical and horizontal wells. I see a drastic reduction in first cost with horizontal loops, slightly more in operating cost, and yes the length of pipe is longer but has little effect on overall system cost. Please let us know what category puts vertical 2x ahead of horizontal.

There are various modeling programs that will give an estimate of thermal performance (ie, operating cost).

Posted By gonegeo on 11 Apr 2011 08:43 AM
Joe,
Would you please define "twice as efficient" Is that in terms of length of pipe, first cost, operating cost??? . I have projects that have used both vertical and horizontal wells. I see a drastic reduction in first cost with horizontal loops, slightly more in operating cost, and yes the length of pipe is longer but has little effect on overall system cost. Please let us know what category puts vertical 2x ahead of horizontal.

I am not Joe....but.... Vertical systems have about twice the amount of heat exchange per running foot than horizontal systems due to the higher density of the ground (usually rock) and the more constant (meaning warmer in heating season and cooler in cooling season) temperature further down. You compensate this with longer loops in horizontal systems. The only "real" difference from an operational point of view is that shorter loops have lesser pressure drop, which sometimes can mean that you need slightly more pumping power (in theory). In the real world, we do not see any system running cost difference between vertical and horizontal loops, and we monitor most of our systems. You see however significantly higher costs associated with vertical the systems, in our neck of the woods about $1000/ton. So we only drill if we have to save this expense.

I'll add that vertical loops are more likely to be surrounded by moving groundwater - which greatly increases heat flow.

so it would cost me less electricity to heat the house with vertical. the wells are abt 6K and to trench would be about 600 plus about 1200 for the slinky. plus there is a clause in the contract if they have to case the hole it would be 10.00 a linear foot more.   that is what scares me.  wf guy said they just had a 7,000.00 overrun on the one job cause of all the casing needed.

If you are in an area where the drilling can not be a "fixed" up front cost, you are rolling the dice. If you have the room to install a horizontal in the overburden, and a proffesional with a good track record doing it, I would go horizontal.
The only way you will see a differance in the cost to operate either system is if there is a flaw in the design. If the feet of pipe installed either horizontal or vertical has the same ewt numbers then the cost to operate will be the same.
Hope this helps
Eric

Posted By rikmeister on 12 Apr 2011 03:03 AM
so it would cost me less electricity to heat the house with vertical. the wells are abt 6K and to trench would be about 600 plus about 1200 for the slinky. plus there is a clause in the contract if they have to case the hole it would be 10.00 a linear foot more.   that is what scares me.  wf guy said they just had a 7,000.00 overrun on the one job cause of all the casing needed.

No, the take home message here what everyone agrees on is that it will cost you the same operating costs (e.g. electrical cost) if a horizontal is possible (no shallow bedrock, enough space etc)!

thanks mates. that is what i was looking for. horizontal is the way to go for me then. I am afraid of the drilling costs.

Posted By joe.ami on 11 Apr 2011 08:17 AM
Vertical loops are twice as efficient..........so only half the pipe is installed. Operating cost difference is virtually nil.
Most of us agree installer is more important than brand. Comfortaire is made by Climatemaster.
j

rik,
By virtually nil, I meant <$100/yr in my neck of the woods and depending on conditions verticals do not always have the lowest op cost. What the other guys said is true, all systems will be designed for the same entering water temperature making op cost similar. Op cost differences come from pumping cost and the greater likelyhood that you will get "a little extra" loop with horizontals (we tend to use standard length rolls so if 550' of pipe is indicated, we will install 600' instead of saving a 50' tail).

We've discussed before that "more efficient" does not always refer to op cost.

gg,
I honestly don't get the confusion. I covered the "efficiency" question by mentioning only 1/2 the pipe is installed and followed that with the comment that op cost difference is virtually nil........it would seem I answered your question before you asked it.

j

gg,
I honestly don't get the confusion. I covered the "efficiency" question by mentioning only 1/2 the pipe is installed and followed that with the comment that op cost difference is virtually nil........it would seem I answered your question before you asked it.

-----------------------

Joe,
I think I knew what you meant, but a casual observer might imply that the first cost is higher because there is more pipe required in the horizontal.  You did say operating cost was the same, but I didn't see mention of the  first cost differences.

GG

one more probably stupid question. i see that the furnaces are labeled vertical and hornizontal as well as left and rigrht. the stupid question is if you go with horizontal ground loop do you get a horizontal furnace or is that just for the space you have available to locate the unit. thanks again.

Horizontal and Vertical in relation to the heat pump is all about what will work best inside your house, and has no relation to the loopfield. The heatpump doesnt know or care what it is hooked up to. It only cares about water flow and temperature.

GG,
Riks original post indicated his price for horizontal or vertical was the same ("the price to do either is the same").
j

I guess drilling vs. horizontal costs are dependent on geography. In the Northeast, drilling has always been more costly.  By a lot.

GG

well just got a price on trenching for horizontal field was 1K or 1200 max. 75.00 per hour. and the wells were 6K plus. so i think gonegeo is correct more and lots more in NE. so i will suffer replanting sod. i really want to thank everyone for you patience and helping me out so much. hopefully they will start after easter.

I will have the same problem here in S.C. When I build some time after 2019, in sandy soil.
I put in a well for water for $1600, but today that same well will cost $3500. No landscaping problems with a new house, all landscaping will be done later.
It will boil down to "Drill or not to Drill" cost per foot trenching vis. cost per foot of drilling.
This is a local problem only i can solve.
Thanks for the insight.