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laserfan

join:2005-01-14
Texas
reply to laserfan

Re: Do Air Conditioners and Heat Pumps cool equally well?

Thanks you guys, I have wondered about our heat pumps for a long time and now I know: they are just more complicated than cooling-only units but provide the same cooling.

I suppose they're susceptible to more maintenance issues (especially leaks) because they run all winter too. Vibration, expansion/contraction etc.

I love the idea that water might improve efficiency. Last year in Texas we had 110 days of 100deg plus temps. This year notso bad but we're in a period of 100+ again w/no end in sight. We also have a severe water problem--I have only rainwater and it hasn't rained in a month so water is an issue. But it seems SUCH a good idea that I wonder why no condensing units have been designed with water in mind i.e. pipes/holes on top and a pan/return pump at the bottom. Hmm gotta build such a thing!

Would have loved to do geothermal but it's rock, rock, and more rock where I live and so finding a contractor (and a home builder willing to work w/same) was problematic when we built.



cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply to boogi man

said by boogi man:

and closed loop is far more efficient. the reason being that a well pump is usually min 1/2hp and frequently far more than that. vs a closed loop system that maybe uses a 1/4hp at most.

Depending on the installation, even considering the additional energy requirements, a GWHP has a better efficiency rating then a GLHP due to a more constant water temperature (cooler then return water in the summer and warmer in winter).


Ken
Premium,MVM
join:2003-06-16
Markle, IN

1 recommendation

reply to boogi man

said by boogi man:

and closed loop is far more efficient.

Absolutely not! Open loop is more efficient than closed in every single unit I have ever looked at. Here are just 2, but I have looked up other brands and they are all more efficient as open loop.

Bryant
Up to 4.6 COP (closed loop)
Up to 27.0 EER (closed loop)
Up to 5.1 COP (open loop)
Up to 31.5 EER (open loop)

Water Furnace



whoaru99

join:2003-12-17
reply to dolphins

said by dolphins:

The heat pumps they had in Jamaica took 2 days to cool the rooms with the thermostat at its lowest setting. They were probably old, had a low BTU rating or both?

Could be either or both. In some ways they're the same.

BTW, the temp setting of the thermostat doesn't affect the rate of cooling or heating.


boogi man

join:2001-11-13
Jacksonville, FL
kudos:1
reply to laserfan

overall system efficiency not just the heat pump itself.
--
my site



Ken
Premium,MVM
join:2003-06-16
Markle, IN

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.



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1

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?
--
my site



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1
reply to Ken

I'd also like to point out that chart is not complete there is no mention of the EWT on the closed loop system.
--
my site



cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply 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)


Ken
Premium,MVM
join:2003-06-16
Markle, IN

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.



cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply to boogi man

said by boogi man:

I'd also like to point out that chart is not complete there is no mention of the EWT on the closed loop system.

It doesn't explicitly state it, but the numbers in the 2nd row of each of the GLHP columns is the EWT. EWT wasn't shown for column width reasons.

AHRI 13256-1 specifies the criteria by which the tests are ran, including entering water temperature. Otherwise manufacturers could overstate their efficiencies by using a supercool liquid for cooling performance, and a superheated liquid for cooling.


boogi man

join:2001-11-13
Jacksonville, FL
kudos:1
reply to Ken

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.
--
my site



cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply 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.


Ken
Premium,MVM
join:2003-06-16
Markle, IN

But what about the pumps for the closed loop, where did they factor that in?



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1

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
--
my site



Ken
Premium,MVM
join:2003-06-16
Markle, IN

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.



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1

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.
--
my site


Ken
Premium,MVM
join:2003-06-16
Markle, IN

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.



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1

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.
--
my site



Ken
Premium,MVM
join:2003-06-16
Markle, IN

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.



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1
reply to laserfan

additionally once you take into account the power consumption difference between a 1/2hp+ well pump and a 1/25thhp circulating pump the efficiency differences i doubt seriously would actually amount to anything on your electric bill
--
my site


iknow
Premium
join:2012-03-25
reply 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/watercycle.html


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom

1 edit
reply 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).


boogi man

join:2001-11-13
Jacksonville, FL
kudos:1
reply 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.
--
my site



Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom

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.


Ken
Premium,MVM
join:2003-06-16
Markle, IN
reply 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.


Netkeys

join:2000-12-08
Fort Lauderdale, FL
Reviews:
·Comcast
reply to Jack_in_VA

Not true. Water transfers heat about 30 times faster then air.

Give it a try. Put a beer in the refrigerator and an other in a iced bucket of water. Get the water to the same temperature as the refrigerator and you'll have a cold beer in minutes with the iced water.

That's why you get colder quicker when swimming then in air at the same temperature. Something I learned during scuba instructions.


Aranarth

join:2011-11-04
Stanwood, MI
Reviews:
·Frontier Communi..
reply to laserfan

I'm using an open loop geothermal system.

In the coldest months in Michigan I use about $250 to $300 worth of electricity.

I'm on a 4" well about 65' deep that can supply two showers and the geothermal all at the same time. We are using about $100 of electricity for the lights, tv's, and other appliances, meaning I'm heating my house for $150 to $200 a month. (Day's can be really short so the lights are on longer.)

The outside discharge loop runs a to a drainage tile system that is also used by our septic system. Keeps the grass green in the back yard...

The water table around here is about 10 -20 feet down and we have many swamps, ponds, streams, and rivers. (this is west MI after all).

In this system the water is never exposed directly to the air since all the piping and drainage systems are underground. While a farmer watering his crops will be loosing water to evaporation, a properly installed geothermal system will have very little water wasted in that fashion.

I would have no issues with anyone withdrawing water from an aquifer for geothermal using this system.



boogi man

join:2001-11-13
Jacksonville, FL
kudos:1

yes i agree if the water isn't being just dumped into a ditch etc but more often than not that is basically what happens. that is wasted water.
--
my site



Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom
reply to Aranarth

said by Aranarth:

I'm using an open loop geothermal system.

In the coldest months in Michigan I use about $250 to $300 worth of electricity.

I'm on a 4" well about 65' deep that can supply two showers and the geothermal all at the same time. We are using about $100 of electricity for the lights, tv's, and other appliances, meaning I'm heating my house for $150 to $200 a month. (Day's can be really short so the lights are on longer.)

The outside discharge loop runs a to a drainage tile system that is also used by our septic system. Keeps the grass green in the back yard...

The water table around here is about 10 -20 feet down and we have many swamps, ponds, streams, and rivers. (this is west MI after all).

In this system the water is never exposed directly to the air since all the piping and drainage systems are underground. While a farmer watering his crops will be loosing water to evaporation, a properly installed geothermal system will have very little water wasted in that fashion.

I would have no issues with anyone withdrawing water from an aquifer for geothermal using this system.

Let me see if I understand this:

The outside discharge loop runs a to a drainage tile system that is also used by our septic system.

The water table around here is about 10 -20 feet down and we have many swamps, ponds, streams, and rivers. (this is west MI after all).

You have your open loop heat pump discharge piped into your septic drain field which is only about 10 - 20 feet above the water table?

You do realize all that water causes the sewage to peculate (wash) into the groundwater contaminating it. Around here it would be illegal to pipe anything like this into the drain field.