This is to continue any discussion/problem solving from the magic number 3 gpm flow thread. 

Here's the story in a nutshell.

Original contractor said he would install 4 ton system (heat loss calculated at 37,767), Indoor design 70F, outdoor design -5.  Contract called for 2 vertical loops, no spec. on depth.
A different bidder for the geo also did a Manual J of some sort and determined that a 3.5 ton system would be sufficient.  No idea on # of loops or depth.

System installed in Oct of 2009.  Contractor said the well drillers dug two 300-foot deep boreholes, and put double-u-bends from Rehau down each.

I've spoken with the secretary at the drillers company.  She looked up the job and verified that two 270-foot deep boreholes were dug (about 15 feet apart).

The first year we had several issues.  Some of that was the contractor had not hooked the zoning panel up right, so we no aux heat on those really cold days (and it was really cold last year).  There were issues with the ductwork as well.  Also, the DSH wasn't installed correctly.

I didn't record EWT much last year (didn't really know about it too much), but did find an old posting on this board where I wrote:

Return from Ground: 32 F   Supply to Ground 27 F    delta of 5 F
Return Air Duct Temp: 66 F   Supply Duct Temp 87 F   delta of 21 F

Bear in mind that the loop manifold was also installed backwards, so I had no idea of the flow rate in the loops.

--------------------------------------------------------------------------------------------------------------------------------------------
Fast forward to the summer:  a/c worked great - no problems at all maintaining cool/dry air
--------------------------------------------------------------------------------------------------------------------------------------------

Last few months:  manifold reinstalled correctly - flow gauges indicate at least 4.5 gpm/loop, so 18 gpm.   The gauges only go up to 4 and they all peg.

Ran system for 30 minutes on stage 1 only. 
Return from Ground: 52 F     Supply to Ground: 45 F   delta of 7
Return Air Duct Temp: 71 F    Supply duct Temp  94 F  delta of 23 F
DSH in Temp              93.7 F   DSH out temp     108 F   delta of 14 F

Here's where it gets interesting, though!  The manual for the system says:
Typical Operating Temps & Pressures:
4 ton system, at 3 gpm/ton  with a EWT of 50 F, water temp drop should be between 5.9 and 7.9, air rise temp should be 25 to 31 degrees.

So it basically looks ok, right?

Out of interest, I contacted the supply house for the actual loops that were installed.  According to them, the only things sold to my contractor during the month of my installation was:
2 300-foot double U coils, fittings, manifold, etc.
I followed up by asking if 300 foot double-u-coils are 300 feet long (300 each way), and the supply house said no.  They are 300 foot total length, 150 each way.

Now it seems like I have two 270-foot boreholes, but with piping in only the top 150 feet.  I saw all the piping when it was on-site.  There were no extension packs or anything.  Just 2 coils.

Reading around the web suggests that just putting extra loops in a borehole doesn't eliminate the need for the right number of boreholes.  If you have a 150 foot hole for a 1 ton system, if you put 2 loops down it, you might get at most 20% more out, so about 1.2 tons of "energy".  But for my 4 ton system, it looks like I only have 2.4 tons of "ground energy", if that.

Finally (!) I did contact the company that makes the Flow Center (26-99 Grundfos (sp?)).  Mine has 2 pumps.  They said it would be safe to disconnect one pump by disconnecting the wires.

I did try that, and the flow gauges on the manifold all read exactly 3 gpm per loop with only 1 of the 2 pumps running.

Ok, discuss!

Posted By stuart.wyss on 24 Nov 2010 09:33 AM
This is to continue any discussion/problem solving from the magic number 3 gpm flow thread. 

Here's the story in a nutshell.

Original contractor said he would install 4 ton system (heat loss calculated at 37,767), Indoor design 70F, outdoor design -5.  Contract called for 2 vertical loops, no spec. on depth.
A different bidder for the geo also did a Manual J of some sort and determined that a 3.5 ton system would be sufficient.  No idea on # of loops or depth.

System installed in Oct of 2009.  Contractor said the well drillers dug two 300-foot deep boreholes, and put double-u-bends from Rehau down each.

I've spoken with the secretary at the drillers company.  She looked up the job and verified that two 270-foot deep boreholes were dug (about 15 feet apart).

The first year we had several issues.  Some of that was the contractor had not hooked the zoning panel up right, so we no aux heat on those really cold days (and it was really cold last year).  There were issues with the ductwork as well.  Also, the DSH wasn't installed correctly.

I didn't record EWT much last year (didn't really know about it too much), but did find an old posting on this board where I wrote:

Return from Ground: 32 F   Supply to Ground 27 F    delta of 5 F
Return Air Duct Temp: 66 F   Supply Duct Temp 87 F   delta of 21 F

Bear in mind that the loop manifold was also installed backwards, so I had no idea of the flow rate in the loops.

--------------------------------------------------------------------------------------------------------------------------------------------
Fast forward to the summer:  a/c worked great - no problems at all maintaining cool/dry air
--------------------------------------------------------------------------------------------------------------------------------------------

Last few months:  manifold reinstalled correctly - flow gauges indicate at least 4.5 gpm/loop, so 18 gpm.   The gauges only go up to 4 and they all peg.

Ran system for 30 minutes on stage 1 only. 
Return from Ground: 52 F     Supply to Ground: 45 F   delta of 7
Return Air Duct Temp: 71 F    Supply duct Temp  94 F  delta of 23 F
DSH in Temp              93.7 F   DSH out temp     108 F   delta of 14 F

Here's where it gets interesting, though!  The manual for the system says:
Typical Operating Temps & Pressures:
4 ton system, at 3 gpm/ton  with a EWT of 50 F, water temp drop should be between 5.9 and 7.9, air rise temp should be 25 to 31 degrees.

So it basically looks ok, right?

Out of interest, I contacted the supply house for the actual loops that were installed.  According to them, the only things sold to my contractor during the month of my installation was:
2 300-foot double U coils, fittings, manifold, etc.
I followed up by asking if 300 foot double-u-coils are 300 feet long (300 each way), and the supply house said no.  They are 300 foot total length, 150 each way.

Now it seems like I have two 270-foot boreholes, but with piping in only the top 150 feet.  I saw all the piping when it was on-site.  There were no extension packs or anything.  Just 2 coils.

Reading around the web suggests that just putting extra loops in a borehole doesn't eliminate the need for the right number of boreholes.  If you have a 150 foot hole for a 1 ton system, if you put 2 loops down it, you might get at most 20% more out, so about 1.2 tons of "energy".  But for my 4 ton system, it looks like I only have 2.4 tons of "ground energy", if that.

Finally (!) I did contact the company that makes the Flow Center (26-99 Grundfos (sp?)).  Mine has 2 pumps.  They said it would be safe to disconnect one pump by disconnecting the wires.

I did try that, and the flow gauges on the manifold all read exactly 3 gpm per loop with only 1 of the 2 pumps running.

Ok, discuss!

Temperatures look OK. So the only reason to doubt everything is the supply house. Well, we stock some of our pipe, so a coil we buy in May might go in in November.

Posted By docjenser on 24 Nov 2010 09:42 AM


  Well, we stock some of our pipe, so a coil we buy in May might go in in November.

Same with us.

Stuart, I understand your skepticism .

What really needs to happen now is to see how the loop performs over the winter.

Unless of course you want to try and measure how much pipe you have in the ground.

Since your manifold is inside, you could isolate each loop and blow the water out as doc as suggested.

As your contract didn't specify how many feet of pipe you were getting,  if you measure and find it is short, you don't have much recourse.

If you let the loop run through the winter and it performs OK,  then all is fine.

I figured there would be a way to measure the pipe in the ground, but short of emptying each pipe, (something my new contractor probably isn't going to do just to see) we'll have to keep an eye on performance.

a WELserver would be expensive to set up for this experiment. Should I just take EWT temps every few days as we enter the season after the system is running for at least 15 minutes?

Posted By stuart.wyss on 24 Nov 2010 10:58 AM
  Should I just take EWT temps every few days as we enter the season after the system is running for at least 15 minutes?

That will give you the info needed.

I would have spaced the bore holes a little further apart, checked that they were arranged perpendicular to the groundwater flow and put in the full 300' as claimed. But I suspect that these are minor issues.

I will chime in with the simple version. If your system is performing to the parameters set forth by the installer, and you are happy with the performance to date and cost to operate to date, it would not matter to me if the bores were 100' and the loops were 50' each. If you were charged by the foot to drill I would care. Also if the conditions I have mentioned are incorrect I would care.
Eric

O.K. I just dugg out my Rehau crap.
Part #100016-324 is a double u-bend pexa 1"cts 300ft coil (1,200ft)

It is my hope that you got what you paid for and the supply house guy "just winged it" when answering your question.
Eric

Ah ha! The supply house told me that my contractor had ordered the same part number, 2 x 100016-324. I guess the supply house had it wrong when they told me what it was. It looks like I have 1200 feet of tubing in each hole! Yay!

My new contractor was by today for a quick check up and he gave me one more piece of data (not sure its usefulness by itself). The pressure in the ground loop when the system wasn't running was 50. (psi?).

The loop (closed and pressurized HDPE) for our Envision units are supposed to be from 40psi to 70psi. Wherever your range should be, you will be able to test for it too when your gauge arrives. :-)

I am gladd I could help, sorry the counter guy at the supply house cast even more dispersions on your project for no other reason than he was to lazy to pull up the rehau specs. I am also sorry this woke jonr up again.
Eric

LOL. I just received the digital Dwyer gauge in the mail. Checked the pressures at the p/t port...it read 42.8 with system off.

Is there a way to mark my topic as "resolved" somehow?

Oh no, you can't do that...some of us here will bang on in the thread for months to come, adding page after page of minutiae while the OP is long gone.

How can you even think of depriving us of our due?

I'm sincerely glad this worked out...you now know far more than before

Posted By stuart.wyss on 24 Nov 2010 07:24 PM
LOL. I just received the digital Dwyer gauge in the mail. Checked the pressures at the p/t port...it read 42.8 with system off.

Is there a way to mark my topic as "resolved" somehow?

So what is the pressure drop (the delta PSI between source in and out)?

Never having shoved things into the p/t ports, is it normal for a little spurt of liquid to come out when removing the probe? Apologies if that sounds a little obscene.

100% normal

Pressure drop was just under 5.

49.6 on one side, and 44.8 on the other side.  Stage 1 running.

Manual states that at EWT 50 F, with 12 gpm total (I have at least 16 gpm right now), pressure drop should be 4.2

Over the weekend, may try disconnecting 1 of the 2 circulation pumps and seeing what happens.

I am also sorry this woke jonr up again. Eric Sackett www.weberwelldrilling.com

Always nice to know there are jerks who can't come up with anything pertinent.

Welcome back,
We missed you while you were busy in other forums.
Isn't this where I start harping about straw men and add hominem since you started the name calling?
Eric

 

I am also sorry this woke jonr up again... add hominem .. Eric Sackett www.weberwelldrilling.com

Look it up, you could learn how to spell it and not start such things at the same time. :-)