 Ken
MVM
join:2003-06-16
Markle, IN |
to boogi man
Re: Do Air Conditioners and Heat Pumps cool equally well?Open Loop still comes out ahead. Open loop pumps water lets say between 50 and 300 feet depending on your water table, closed loop pumps the same volume of water 600 feet. So you start with a more efficient heat pump and add half the pumping capacity and you are in even better shape. A closed loop which is less efficient to begin with, and on top of that you have to add basically 2 to 3 times the pumping capacity. |
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i don't see how you're coming up with 2-3x's pumping capacity. if that were the case the pumps needed for a closed loop system would be larger than the pumps needed for a well. 2.5gpm per ton in residential systems according to FHP is what's needed. now i can tell you that if you through the loops in contact with each other in the hole then yeah you'll lose some efficiency however a properly planned and executed closed loop system won't have that issue.
so if it takes 1/2hp to move say 5gpm out of the ground and takes 1/4hp to push 5gpm through a loop. which takes less energy? |
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 cdruGo Colts
MVM
join:2003-05-14
Fort Wayne, IN |
to Ken
said by Ken:Open Loop still comes out ahead. Open loop pumps water lets say between 50 and 300 feet depending on your water table, closed loop pumps the same volume of water 600 feet.
It requires less power to circulate water around a closed loop then it does to pump it out of a open loop (presuming typical installation) |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-2 9:46 am
Closed loop has much more pipe, and the pipe is much smaller leading to much more friction. I don't see how pumping water up 150 feet through a 1.5" pipe is going to cost more than pumping water horizontal 600 feet through a series of 3/4" pipes. However even if I am wrong, the fact that the open loop heat pump is more efficient you are still going to come out ahead. This is why people choose open loop, it's cheaper to install and cheaper to operate. I have never heard anyone try to say a closed loop is cheaper to run than an open loop. |
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if closed loop isn't cheaper it's due to how the loop was constructed and laid out. i.e. the pipes are to close together and the heat is being transferred back to the intake side. i don't know the friction math off hand but i do know that the smaller the pipe the more resistance is found however the friction increase aren't where efficiency is lost. it's lost at the inlet temps and if done right the inlet temps will be the same or very close to the temps of an open loop system thereby making closed loop more efficient and more enviro friendly based on less water wasted and less power consumed than air-air. which is the biggest draw to geo-therm less power required for the same work compared to air-air.
most people it's not worth the upfront cost on a retrofit but if you have a pond like i do and/or are doing new construction the loops are much easier to place before the building is built. |
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cdruGo Colts
MVM
join:2003-05-14
Fort Wayne, IN |
to Ken
said by Ken:I have never heard anyone try to say a closed loop is cheaper to run than an open loop. Here, about half way down the page: quote:
So the open loop system is providing 10,300 more BTU’s than the closed loop system due to the elevated EWT. Open loop system is 435% eff vs. the closed loop operating at 371% eff. The thing that’s missing is the well pump. The well pump runs 100% of the time that the heat pump is running (obviously turns off when the heat pump shuts down). A residential variable speed well pump will draw ~ 5 amps or more at lower flow rates. This equates to another 1.2 KW and takes the total COP down to 3.12. (or 312% eff). At this rate the closed loop system is more efficient with less operating costs. It’s the turtle that wins the race in this example.
It's just one example. And while it may be cheaper in the winter, it may be more expensive in the summer. It's all variable to the exact characteristics of the installation. There is also non-monetary considerations such as can the well support the demands, what to do with the discharge water, water quality, etc. |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-2 9:58 am
But what about the pumps for the closed loop, where did they factor that in? |
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they do use power but almost negligible amounts. last i spoke to the FHP rep in my area they were talking about a 1/25th hp pump being able to do the job which when running is drawing less than 1A |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-2 10:09 am
We have been talking about putting in a geothermal system, and I have been researching them for the past 3-4 months. Even if I'm wrong about that pump, everything I have seen in that time shows the open loop system overall is cheaper to operate than closed loop. I have read many different sites, and I have never seen anyone make the case that the closed loop is overall more efficient. |
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said by Ken:We have been talking about putting in a geothermal system, and I have been researching them for the past 3-4 months. Even if I'm wrong about that pump, everything I have seen in that time shows the open loop system overall is cheaper to operate than closed loop. I have read many different sites, and I have never seen anyone make the case that the closed loop is overall more efficient.
well now you have. i had a geothermal system that was open loop and worked for a large HVAC/R co i've since moved on from both but learned a lot from the actual manufacturer and our local reps and actual HVAC/R degreed engineers that I worked with. |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-2 10:25 am
I'm going to need some facts to back up your claim, as it doesn't fit in with what I'm hearing out of the rest of the industry. |
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read what you posted. the inlet water temps are the problem. get them down during the cooling season and the lost efficiency returns plus the lower pump draw equals more efficient. 2+2 still equals 4 no funny math needed it's all right there. do what you want with your water there. in the end the difference in the bill is going to maybe be $10-15/m depending on your electric rates. for me the closed loop isn't nearly as much about my power bill is it is about the wanton wasting of good water so i can be cool. |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-2 10:41 am
Open loop inlet water temps are lower in the summer and warmer in the winter, which makes it better. I don't see how you are getting something different out of anything I posted. I want the system that is cheapest to operate, if the closed loop is cheaper then I want to know about it. But dozens of things I have read all agree the open loop is cheaper to operate. Wasting of water is just an added bonus of open loop for me as I have a pond that is constantly low and could really use that water. |
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iknow
Premium Member
join:2012-03-25 |
to boogi man
said by boogi man:read what you posted. the inlet water temps are the problem. get them down during the cooling season and the lost efficiency returns plus the lower pump draw equals more efficient. 2+2 still equals 4 no funny math needed it's all right there. do what you want with your water there. in the end the difference in the bill is going to maybe be $10-15/m depending on your electric rates. for me the closed loop isn't nearly as much about my power bill is it is about the wanton wasting of good water so i can be cool.
show how water is wasted. » ga.water.usgs.gov/edu/wa ··· cle.html |
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1 edit |
to cdru
said by cdru: There is also non-monetary considerations such as can the well support the demands, what to do with the discharge water, water quality, etc.
Exactly. Misuse of a valuable resource to gain maybe a few points of efficiency if any. In fact the situation with the reservoirs in my old county is so critical they are getting ready to put the screeching halt to lawn watering and car washing (unless in a commercial car-wash with water reclaiming). |
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to iknow
talking about drinkable water resources. it takes many many years for the aquifer recharge cycle to take place. that's where it's wasted. |
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said by boogi man:talking about drinkable water resources. it takes many many years for the aquifer recharge cycle to take place. that's where it's wasted.
In some instances they're never replenished. |
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Ken
MVM
join:2003-06-16
Markle, IN |
to Jack_in_VA
What you call misuse I call using the resource to it's full potential. If I pump roughly a million gallons a year from the aquifer to heat and cool my house while the farmer next door is pumping a million gallons a week from the same aquifer to water his field I don't see how I am misusing anything. |
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said by Ken:What you call misuse I call using the resource to it's full potential. If I pump roughly a million gallons a year from the aquifer to heat and cool my house while the farmer next door is pumping a million gallons a week from the same aquifer to water his field I don't see how I am misusing anything.
I've seen it said that the average US farmer feeds 155 people. Are you having 155 people over for dinner tonight in your nice cool house?  |
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 Nick_L
Premium Member
join:2003-01-22
Pittsburgh, PA |
Nick_L to Ken
Premium Member
2012-Aug-5 7:36 am
to Ken
said by Ken:If I pump roughly a million gallons a year from the aquifer to heat and cool my house while the farmer next door is pumping a million gallons a week from the same aquifer to water his field I don't see how I am misusing anything.
Allow me to assist you in seeing: Both you and the farmer have an end goal. The farmer wants to nurture his crops so he can sell them at market, provide for his family and help sustain the food supply for our country. You want to be comfortable. The farmer has one option for watering his crops: Water. You, on the other hand, have several options. I know everyone is not effected to the same degree, but the United States is experiencing the worst drought in 60+ years. Over two-thirds of the country is at some level of drought emergency. Less water coming down means an aquifer that will be slower to replenish. Didn't you mention pond? Why is a closed loop at the bottom of the pond not an option? |
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Ken
MVM
join:2003-06-16
Markle, IN |
Ken
MVM
2012-Aug-5 8:33 am
said by Nick_L:Didn't you mention pond? Why is a closed loop at the bottom of the pond not an option?
It is an option. It's more expensive to install, more expensive to operate, and doesn't help keep the pond full. Open loop is cheaper to install, cheaper to operate, and keeps the pond full. |
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 tstolze
Premium Member
join:2003-08-08
O Fallon, MO |
tstolze
Premium Member
2012-Aug-5 9:20 am
said by Ken 
It is an option. It's more expensive to install, more expensive to operate, and doesn't help keep the pond full. Open loop is cheaper to install, cheaper to operate, and keeps the pond full.
Although more efficient due to steady water temperatures, the cost of running a well pump and pump maintenance/replacement often put the operation cost higher than a closed loop system. |
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cdruGo Colts
MVM
join:2003-05-14
Fort Wayne, IN |
cdru
MVM
2012-Aug-5 9:27 am
said by tstolze:Although more efficient due to steady water temperatures, the cost of running a well pump and pump maintenance/replacement often put the operation cost higher than a closed loop system.
And now the discussion has gone full circle. |
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to Ken
how far away from the pond are you? i'm really curious about the particulars of your install that would make a CL system in a pond more expensive than a well. generally the pond, lake stream option is one of the cheapest as it requires very little trenching/digging comparatively. |
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| boogi man |
to tstolze
the thing with a CL system in a body of water is that it's temp may not swing all that far depending on depth clarity of water and other local factors. |
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to cdru
Not to mention of course, completely off-topic!  |
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Ken
MVM
join:2003-06-16
Markle, IN |
to boogi man
said by boogi man:how far away from the pond are you? i'm really curious about the particulars of your install that would make a CL system in a pond more expensive than a well. generally the pond, lake stream option is one of the cheapest as it requires very little trenching/digging comparatively.
I'm going to repeat myself one last time. From every single bit of research I have pulled up from dozens upon dozens of different sources every single one of them has all agreed that open loop is cheaper than closed loop every single time. At no point in the last several months of researching this have I ever heard a single time that any possible way is closed loop cheaper than open loop. My particular situation my pond is right next to my house, and I have 5 acres of land. I could easily put in a standard horizontal loop in the ground, I could put in a pond loop, or I could do open loop. I am going with open loop because according to everything I have ever seen it is always cheaper to operate than the other methods. If some how closed loop is cheaper then I want to see some evidence of this, but so far nobody has shown me anything accept the link cdru posted that said closed loop is better, but that doesn't mean much as they make more money off a closed loop install and they didn't factor in the cost of the pumps on the closed loop making it an unfair comparison anyway. When it comes to unbiased sources not out to make money I can't find one that doesn't say open source is cheaper. If you want to prove me wrong feel free to do so with some link to something unbiased showing closed loop is cheaper to operate. |
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 leibold
MVM
join:2002-07-09
Sunnyvale, CA
ZyXEL P-663HN-51
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said by New York City Geothermal Heat Pump Manual :As closed loop piping and the required grouting material add
another layer of heat transfer resistance, the closed loop system is
designed for lower winter entering water temperatures and higher
summer entering temperature. These wider temperature ranges
reduce the effective capacity and efficiency of the heat pump
system. Closed loop piping costs are typically in the same range
as the cost of the heat pumps and thus add to the overall cost of
the installation. Generally, these closed loop systems are more
first cost than the above systems. A compensating increase in the
overall system efficiency can be anticipated by the reduction in
loop pumping costs. However, the requirement for slightly larger
equipment remains a disadvantage. You won't find anything that will say that closed-loop is unconditionally better then open-loop because in most situations where both open-loop and closed-loop are feasible the open-loop system tends to have a lower initial cost. The cost difference may not be large (or even in favor of the closed-loop system) when new wells need to be drilled but the difference is significant when an existing well can be utilized for the open-loop. It is easy to determine operational costs for the small circulation pump in a closed-loop system (the effort to circulate the water in a closed loop is the same no matter how deep the loops are buried). The same does not apply for open-loop systems where it makes a big differences on the lifting power of the well pump depending on the depth of the water table. This means a true comparison of the operational costs of open-loop and closed-loop systems requires a site-specific analysis. Even with operational costs likely to be lower in a closed-loop system the question remains whether the difference is large enough to make up for the higher up front installation costs ? |
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iknow
Premium Member
join:2012-03-25 |
to tomupnorth
said by tomupnorth:Not to mention of course, completely off-topic! how's that? a geothermal system cools better than an air source AC, so the subject turned to that, and then details about the various geothermal systems had to be discussed to be complete!. there's no sense in using something that may not be beneficial for various reasons. |
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said by iknow:said by tomupnorth:Not to mention of course, completely off-topic! how's that? a geothermal system cools better than an air source AC, so the subject turned to that, and then details about the various geothermal systems had to be discussed to be complete!. there's no sense in using something that may not be beneficial for various reasons. Pretty much because he asked if heat pumps cool as good as non-heat pumps. The answer is a simple "yes." The ensuing geothermal discussion regarding open vs closed loops has been interesting, but it doesn't have any bearing on what he asked. |
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