Steve Dragger
New Member
Posts:10
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| 07 Jan 2013 10:55 AM |
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Long summary, bought a house, have 5 ton and 3 ton Bryant Geothermals 27 seer. Well dried up, dug another, geos require 8pm and 5gpm, well provides 6gmp. Installed 5500G cistern fed by 6gpm and a valve that lets me run open or closed loop (back to cistern). So with the cistern I think that's something like 36 hours of runtime with backfill if I don't close the loop. (That's based on dead of winter in ohio, 16-20degrees out), Assuming it will easily run 15 out of 30 minutes. So I closed the loop, and shortly after chilled my water to the point of thermal warnings on the geo. (trying to chill water past 32degrees)
It seems to me this would have been obvious to someone who knows geothermal (I am not this person) yet everyone in the chain said "oh yeah do that, just add a cistern" Now I have the option to add a 2nd 5500gallon (I left a spot next to the original) but I'm going to run into the same thing right?.
The other suggestion of my goethermal company was to put antifreeze in the cistern and run closed loop forever, but again won't I run into the same problem (water can only get so cold even with antifreeze.
Now I could run partial open (dump 5-6gpm and let the rest loop back to cistern) but I don't know if that will still "over chill" the system.
At a huge loss and my geo guys (2 different companies now) have been clueless.
Is there a geo/hydro specialist I could hire for this to do measurements and calculations or ??
Suggestions or a pointer at who to talk to?
On the bright side, when the geo was running and had new water, it heated REALLY well (nice hot air) Now I'm running on heat $trip$ so should have a nice million dollar heating bill this week. |
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jonr
Senior Member
Posts:5341
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| 07 Jan 2013 01:09 PM |
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I think your choices are to add another well or add some ground loops. Tanks can get you through a day or two, but weather doesn't cooperate like that.
If that is too expensive and you want to try to get by with a tank and supplemental electric (it will outperform only supplemental electric), make sure that the well pump runs whenever the tank is a few degrees colder than the well water temperature. It should NOT be controlled by the heat pumps (since the whole idea is to store up btus from the well during the off periods). |
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DSB62
New Member
Posts:4
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| 08 Jan 2013 11:23 AM |
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I am gonna be cautious here, and without additional information I can only comment on what you have listed about the system. You have 2 units a 5 ton and a 3 ton = 8 tons. so i am assuming based on the size of units you have an approximate 4000 sf home. "geos require 8gpm and 5gpm", which = 13gpm total or 1.625gpm/ton installed. There are old rules of thumbs that have been applied historically that have been proven not to work. In today's sizing for units you have listed you need to consider that Geo requires a minimum 2 gpm per ton for open loop and 3 GPM per ton for closed loop. You have a hybrid system that is trying to make geo function without allowance for heat transfer other than within a tank. Without knowing the cistern location and the function or movement within the cistern it is difficult to evaluate it. I use TES or thermal energy storage in all of my commercial geo designs which amount to a cistern if applied correctly. Without agitation or movement within your cistern you cannot possibly expect any significant heat transfer to occur and nothing was mentioned relative to agitation. This is why you have an approximate value or operating run time for operating capacity. Geo works when it is applied correctly which is to use Mother Earth as your heating/coiling coil. Your goal should be be to reduce your cost for comfort by being able to use your system year round and sleep at night. There is an easy fix to this, I would not spend another dime on a cistern. I would address your flow issue and learn how Geo Thermal works to be applied correctly. Your heat pumps carry value, but I have an old saying, If anything can go wrong in a geo thermal system it will be in the loop calculations and it appears your calcs were cut short. |
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HHH
New Member
Posts:81
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| 08 Jan 2013 12:24 PM |
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Where are you located? |
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ChrisJ
Basic Member
Posts:277
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| 08 Jan 2013 12:50 PM |
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http://www.greenbuildingtalk.com/Forums/tabid/53/aff/13/aft/80494/afv/topic/Default.aspx
More info here at Steve's other thread.
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jonr
Senior Member
Posts:5341
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| 08 Jan 2013 01:44 PM |
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More info here at Steve's other thread. Looks like the huge change since then is that total available flow dropped in half. That changes things from very close to impossible. |
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DSB62
New Member
Posts:4
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| 08 Jan 2013 01:49 PM |
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We are located in MI and work and apply geo globally. Keep in mind the heat pumps cop is a product of "ewt" entering water temperature, flow and PS. All manufacturers have bench marked publications which direct the installer to the be able to determine the performance of the heat pump and if there is any problems they should simply read the charts compare to the gauges and pretty quickly determine what the issue is.
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DSB62
New Member
Posts:4
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| 08 Jan 2013 01:57 PM |
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You are absolutely right, i rewrote my first post because i clearly stated you have big problems it is impossible for your hybrid to work. Being a new member joining at the request of a vet i thought i would be nice, haha
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ICFHybrid
Veteran Member
Posts:3039
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| 08 Jan 2013 02:00 PM |
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How much land do you have and where are you dumping all this water right now? |
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DSB62
New Member
Posts:4
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| 08 Jan 2013 02:08 PM |
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open loop discharge from an aqua-fir must be returned to the same aqua-fir epa is not a big fan of open loop discharge of ground water unless it is a dug well not drilled
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waterpirate
Basic Member
Posts:467
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| 09 Jan 2013 07:30 AM |
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Class 5 injection wells are truly a slippery slope and no 1 rule applies anywhere. If you are in Ohio I would recomend 2 people to you. Mark Custis, and Joe Hardin. They both coach solutions to hard problems in your locale and are very knowledgable. They run through here infrequentl. You could contact them at the other site.
Eric |
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| Eric Sackett<br>www.weberwelldrilling.com<br >Visit our Geothermal Resource Center! |
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joe.ami
Veteran Member
Posts:4377
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| 09 Jan 2013 08:59 AM |
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Posted By DSB62 on 08 Jan 2013 11:23 AM
Hi and welcome.
New to the forums you will learn quickly not to take things for granted. Particularly on an install that doesn't work. We've not recieved replys from the OP (original poster) so this is speculation, but I'll offer it anyway to illustrate what we routinely find here.
I would also offer that along the way I've come to realize that my truisms were geographically true. I've since learned quite a bit from other contributing pros about challanges in their respective AO's.
I am gonna be cautious here, and without additional information I can only comment on what you have listed about the system. You have 2 units a 5 ton and a 3 ton = 8 tons. so i am assuming based on the size of units you have an approximate 4000 sf home.
2,000 to 3,000 square feet wouldn't be a suprise.
"geos require 8gpm and 5gpm", which = 13gpm total or 1.625gpm/ton installed. There are old rules of thumbs that have been applied historically that have been proven not to work. In today's sizing for units you have listed you need to consider that Geo requires a minimum 2 gpm per ton for open loop and 3 GPM per ton for closed loop.
I don't know if you are referring to commercial systems or northern MI, but properly sized systems run fine on 1.5 GPM in mid MI and Ohio (I have systems in place hard metered to prevent greater flow).
Your heat pumps carry value, but I have an old saying, If anything can go wrong in a geo thermal system it will be in the loop calculations and it appears your calcs were cut short.
I'm gonna guess it's wrong from the ground up. You will be apalled to discover that many of these systems are sized by SF (not manual J) and designed for 100% of the load.
O.P.
If we could start with a manual J load for your home and location in OH you may find that your system is sized heavily for demand. If your installer was extremely ignorant to sizing issues, we may find that you need quite a bit less tonnage than installed which would mean quite a bit less water is required.
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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