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bmancanfly
New Member
Posts:79
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| 07 Feb 2009 02:55 PM |
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Can you explain what exactly a two stage compressor is and what the advantages are.
Also, what company manufactures the "026 model"
thanks |
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Palace Geothermal
Veteran Member
Posts:1609
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| 07 Feb 2009 05:07 PM |
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Posted By bmancanfly on 02/07/2009 1:43 PM
One last question. Could I dig a trench say 5-7 ft deep, lay a row of slinky, back fill say 2 ft, and lay another row on top of the first in the same trench. Thereby doubling the feet of pipe in that trench.
This would not really work in your situation. If you could dig 10' , back fill 4', then lay another slinky, you might see some benefit.
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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joe.ami
Veteran Member
Posts:4377
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| 07 Feb 2009 05:21 PM |
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Climatemaster makes a TTV026 two stage 2 ton. They do not happen to make a 2.5 ton in that model.
2 stage compressor has a low gear and a high gear and attempts to use the minimum effort to achieve your setpoint.
Regarding flow in different loop lengths. 10% or 50% really doesn't matter. Shorter loops will pass less solution, but not different gpms...the path of least resistance is only so until volume makes a different path less resistant. Some manufacturers may not agree, but some of them show DSH's without buffer tanks.....wives tails.
J |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 07 Feb 2009 05:23 PM |
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Should have said gpm/ft
j |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Palace Geothermal
Veteran Member
Posts:1609
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| 07 Feb 2009 05:28 PM |
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Joe...
are you saying that if you have a two loops, one 1000' long and one 500' long, both the same size pipe, both hooked to the same header that the rate of flow will be the same on each loop? |
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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joe.ami
Veteran Member
Posts:4377
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| 08 Feb 2009 02:02 AM |
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gpm/ft....
yes
j |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 08 Feb 2009 02:05 AM |
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My mantra; its all about footprint applies, if you have different sized loops and even different flow rates, enough still works.
manufacturers suggest everything has to be evenly divided, but loop design says how many feet, not how you divide it.
J |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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geo fan
Basic Member
Posts:408
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| 08 Feb 2009 08:28 AM |
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I must say Im confused by your statement , when determining pipe size you need to know required gpm and length , This is because the length of the pipe has a direct relationship with the gpm the pipe can handle
This is not only true in hydronics but refrigerant piping , gas piping , med gas . really anything
The reason Im confused is in your last statement seems to acknowledge this but the one before contradicts , If you could explain a little
further it might clear it up for me, what is an old wives tale?
http://reconditioncouplings.com/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=2&MMN_position=3:3 |
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engineer
Veteran Member
Posts:2749
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| 08 Feb 2009 12:32 PM |
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I need to get and start using closed loop design software.
I deliberately wrote "026 models" without specifying brand since several major geo unit makers all use Copeland Ultratech 2 stage compressors. All same tonnage units (026, 038, 049, 060, 072) whether from WF, CM, and I believe also FHP and Hydron and others all use same compressors from Copeland, so units capacities and operation are quite similar.
The particular advantage of two stage units is longer run times in low stage during humid but not overly hot weather (such as darn near every night in Florida from about May through September). Long run times dehumidify better, which allows greater comfort for most folks at higher thermostat setpoints. Other benefits of long low stage runs are greater efficiency, more even distribution of heat / cool throughout house, and quieter operation. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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Palace Geothermal
Veteran Member
Posts:1609
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| 08 Feb 2009 12:40 PM |
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With 1" pipe you, need 3 gpm to maintain Reynolds 2500.
A 1'' pipe 500' long with 3 gpm will have 3.33 ft of head friction loss.
A 1" pipe 1000' long with 3 gpm will have 6.66 ft of head friction loss.
There is no way that you will get the same flow through these two loops if they are both hooked to the same pump.
As the table below shows, you can get 2 gpm thru the 1000' and 3 gpm thru the 500'
or you can get 3 gpm through the 1000' and 4.45 thru the 500'.
But you can not get equal flow thru the 1000' and 500' loops.
Will both of the loops exchange heat with the ground? Yes they will. As long as you have RE above 2500 in both loops they will both exchange heat effectively. They just will not flow at the same rate.
If you want to have equal flow thru loops, you need to have equal pressure and equal friction loss.
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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joe.ami
Veteran Member
Posts:4377
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| 08 Feb 2009 10:27 PM |
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You'll notice on the table that your friction loss/ft is constant (.00666/ft). More feet more friction right, but with one pump at 500'/ton all the pump sees is 2000' or 13.32 head loss/ft.
Wether we speak of each individual foot of pipe or the entire field this holds up. The table only stands up when loops are compared seperately and pumped independantly.
I'm not trying to be contrary, what's really the end issue is in repair work (new installs will obviously have equal sized loops for convenience). If you need more heat exchange in a repair and don't know what the first fellow put in the ground, you can add without specific knowledge of loop size as long as pump gets desired flow out of the system. In floor radiant is a very good example of set btu/ft (and therefore flow) values for circuits of different sizes on a common pump (providing zone valves are not employed).
GF...I mispoke a fine point, let's say... in designing a loop field we must factor btu transfer required and required GPM to select pipe size and length.
Dewayne, I'd be happy to agree to disagree:)
J |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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Palace Geothermal
Veteran Member
Posts:1609
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| 08 Feb 2009 11:07 PM |
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Posted By joe.ami on 02/08/2009 10:27 PM
Dewayne, I'd be happy to agree to disagree:)
J Deal :)
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Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
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bmancanfly
New Member
Posts:79
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| 10 Feb 2009 02:10 PM |
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I've decided to go with a 2 stage unit which I'm told operates like a 2 ton on low and a 3 ton on high. Seems perfect for my home and climate. But I'm still getting hugely divergent opinions on the loop length. I'm really puzzled how "professionals" in this field can come up with such different numbers. I've gotten quotes as low as two 65-75 ft trenches with 800ft slinkies in each trench to four 135 ft trenches with 750 slinkies in each trench. I don't want to undersize my loop field but what gives? |
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geo fan
Basic Member
Posts:408
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| 10 Feb 2009 04:54 PM |
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My understanding (not a water source guy ) the more the better , Untill there is to much :)
One guy may be tight designing while another might be giving himself allot of wiggle room
All things being equal I would want extra pipe in the ground
even if it where to only be there to be handle possible future expansion, and to maintan higher eff
but thats me
also it is possible one or some are guessing |
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joe.ami
Veteran Member
Posts:4377
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| 10 Feb 2009 10:01 PM |
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Have you asked a local installer? Or just DIY sales and us?
Local installers will give the best design, everyone else is going to hedge their bets.
J |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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engineer
Veteran Member
Posts:2749
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| 10 Feb 2009 10:03 PM |
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There is always some uncertainty as to soil composition and dampness, both of which can significantly affect heat transfer. Designer gets to decide whether to err on the side of caution or first cost. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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Alex_in_FL
New Member
Posts:96
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| 14 Feb 2009 03:16 PM |
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Over where I live (central FL on the east coast - Merritt Island), groundwater temps are about 75-78 F. This may sound high but these are numbers taken from monitoring wells (10-60 feet deep generally).
Earth temperatures varily by depth. The top few feet can change by +/-10 or more degrees due to seasonal temperatures. Given this I believ you do want to go 6 feet deep (or even more!).
If central Florida has a drought (and the current wildland fire community predicts longer than normal dry season here in Brevard) the soil both dries out and gets hotter. This results in much worse heat transfer by the loop.
Night time temps here can stay in the high 70s so even a ground temp of 78 F can provide benefits over the ASHP. Plus water transfers heat more efficiently than air (about 20% better if I recall correctly).
Loop length depends upon many, many factors thus can vary considerably. Key factors include soil temp, soil type, soil moisture, pipe type, pipe spacing, grout used (vertical), soil-to-pipe contact, etc. Without a soil sample, estimators don't know the right soil properties. That could cause a 10-15% difference in length estimates alone. Thus for lengths to be within 15% is reasonable error.
Best of luck to you!
Alex |
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Alex_in_FL
New Member
Posts:96
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| 14 Feb 2009 03:22 PM |
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"One last question. Could I dig a trench say 5-7 ft deep, lay a row of slinky, back fill say 2 ft, and lay another row on top of the first in the same trench. Thereby doubling the feet of pipe in that trench."
Yes you can do it. But no, that will not count as twice as much pipe for heat transfer (but will for friction resistance). The reason is heat transfer in soil and delta Temps. The lower pipe will warm the soil and make the upper layer of pipe less effective.
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bmancanfly
New Member
Posts:79
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| 19 Feb 2009 04:44 PM |
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Is it worth it to bury some sort of irrigation system (drip or otherwise) above the buried slinkies to keep the soil moist during dry spells? |
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engineer
Veteran Member
Posts:2749
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| 19 Feb 2009 07:51 PM |
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Alex - That's the challenge facing us here - getting enough loop in the ground so EWTs are low enough to make geo compare favorably with airsource units.
Bmancanfly - seems like cheap insurance. It may also greatly help with initial compaction / reducing air voids near loop tubing.
Last summer we were walking a new geo owner in Austin dealing with a drought and record high temps - had them water the heck out of their loop field and it helped, though it used quite a bit of water. I figure water lines nearer the loop tubing could be both more efficient with water and more effective. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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