I currently have 2800 ft of 1" line in a vertical loop .My head pressure is about 25psi. My depth is only about 5ft and was considering adding 1000 ft 1" slinky loop at a depth of 7+ft depth througth what is currently a ditch and may hold water in a wet spring .Is this a good option and will my pumps handle the extra head pressure. Any advice helpful .

waddaya have for antifreeze and what concentration?

I have 25 gallons of 70% glycol protek 100 in loop.

2800 feet of 1 inch vertical loop at a depth of 5 foot= 560 vertical loops?

I think you meant 2800 of horizontal? Having 70% glycol means your fluid is very viscous. Simply google friction loss and flow rates, compare with the performance chart for your pump, and presto. you could also get some free trial software and input your current data and add new data add nauseam to see where you end up.
Eric

If you can, add the new loop in parallel with the old one - with a valve to balance the flow.

Posted By jonr on 31 Mar 2012 08:50 AM
If you can, add the new loop in parallel with the old one - with a valve to balance the flow.

Get the flow balanced by installing like sized circuits. Valves and throttling are not encouraged by pros in geo loops.......frankly many of us do not think "balance" is as important as others.

protek is around 50% glycol. so with 70% protek,you are prolly around 35% glycol.

Jim. Your description of what you actually have needs clarification. That said adding a circuit or two in parallel will allow your pump to push more gpm.

IMO balance does matter

Posted By geodude on 31 Mar 2012 10:04 AM
protek is around 50% glycol. so with 70% protek,you are prolly around 35% glycol.

Jim. Your description of what you actually have needs clarification. That said adding a circuit or two in parallel will allow your pump to push more gpm.

IMO balance does matter

OK- Why? Please explain how balanced loops extract more btus from the ground than unbalanced loops.


Would you endorse throttling to achieve this balance?

I think it is pertinant to OPs concerns or I would have started a new thread.

@Joe Easy there big fella.

Your previous post explained that you balance flow by installing like size circuits. This I agree with.

But then you write ".frankly many of us do not think "balance" is as important as others" This I disagree with.

To understand why unbalanced temperatures (adjusted using flows) in unequal lengths don't extract maximum btus, simply imagine an extreme case where you have a 1' section of loop and a 1000' section in parallel. Almost all of the flow will be through the short section (a short circuit) and the system will not function well at all. But throttle the short section and it will work fine (a tiny bit better than using only the 1000' section). Basic thermodynamics, as encouraged by engineers.

A restricted 1000' loop in parallel with a unrestricted 2800' loop is less pressure drop than just a 2800' loop (and far less than 2800' in series with 1000').

A balanced pair of loops without throttling is even better, but not always practical or what the OP proposed.

Posted By jonr on 31 Mar 2012 12:00 PM
A restricted 1000' loop in parallel with a unrestricted 2800' loop
is less pressure drop than just a 2800' loop ...

That's barely true (and highly misleading) for the typical pressures &
flow rates encountered in residential closed loops. A centrifugal circ
pump is a nearly-constant-pressure device. For example, the output
pressure of a Grundfos UP26-99 falls by only 12% when its flow rate
is doubled from 5 to 10 GPM, and only 25% when tripled to 15 GPM.

Thus, adding circuits in parallel increases total flow without greatly
diminishing the flow in previously existing circuits (providing that
the new circuit isn't a ridiculous 1' direct short across a 1000' loop).

So, joe.ami is correct that "balancing-by-restriction" has little/no
benefit, unless the loops in question are grossly mismatched.

Also be aware of the "self-equalizing" tendency of flowing fluids.
Since dynamic head increases much more rapidly than GPM, the
flow through parallel pipes DOES NOT split in inverse proportion
to their lengths -- and thus, the shorter loop doesn't hog as much
flow as might have been expected, based on their lengths alone.

...the proof of this is left as an exercise for the student,

Looby

Thank you Looby.
For us Dumb A's I have always said "it is only the path of least resistence until......."

For everybody, the penalty for mismatched loops acording to the family engineer might be in the neighborhood of 10% (pump energy). The benefit of additional loop is likely greater.......unless you only add a foot. All loops gather BTUs. All loops cost pump energy. The Math is easy. The industry standard is stated- but mismatched loops (greater than a foot) are still likely beneficial.....throttling-not so much.

It is all pure speculation until Jim responds with a more descriptive picture of what his loopfeild is comprised of.

If for some reason (like an AWOL contractor maybe?) he could not pin down exactly what his field is comprised of,

Then if his ewt deemed the need for more loop (do we even know this?)

I would consider adding a slinky loop with, yes wait for it, a valve to help optimize heat transfer.

Amusing that "shorter and/or higher flow parallel loops dilute the temperature and reduce COP" was missed (as demonstrated elsewhere in this forum with an actual test). A 5-10%, maybe 25% difference in loops lengths and experts agree - not worth worrying about. On the other hand, 155% and you will notice the performance decrease (unless you throttle).

http://www1.eere.energy.gov/geothermal/pdfs/ghp_workshop_johnson.pdf

http://www.rehau.com/cms/servlet/linkableblob/US_en/68106/data/RAUGEOTechicalManual_827600_07-09-data.pdf?view=DEFAULT

http://blog.heatspring.com/geothermal-ground-loop/

I agree with geodude. As I said, if it is easy to match the loops without a valve - do that.

"Amusing that "shorter and/or higher flow parallel loops dilute the temperature and reduce COP" was missed (as demonstrated elsewhere in this forum with an actual test)."

....so then creating artificial additional pressure for the pump to overcome is more efficient?....or are we perhaps swapping one kwh for another?

Posted By jonr on 01 Apr 2012 08:01 AM

On the other hand, 155% and you will notice the performance decrease (unless you throttle).

On the other other hand, if he really has a single 2800' x 1"
circuit (w PG antifreeze) the loop is already "over throttled"
due to its excessive length. (Feel free to do the math.)

So, what's a girl to do? Add another loop -- plus a valve to
make sure that the second loop is every bit as inefficient as
the first?

...I've cut it three times already, and it's still too short!

Looby

Posted By jonr on 01 Apr 2012 08:01 AM
Amusing that "shorter and/or higher flow parallel loops dilute the temperature ..."

Amusing fact: temperature is not heat.

How about splicing into existing loop? Is 1" pipe easy to make a slinky coil with to fit a 42"-48"trench?

yes

so then creating artificial additional pressure for the pump to overcome is more efficient?

Sounds like you are alluding to another myth - that restricting the flow through a pump increases its power draw (it decreases it).