Equipment Sizing for Geothermal

[dan sw fl]

http://www.energywisestructures.com/

[genduct]

To summarize, you have 2 questions not 1
!. Proper size of equipment for your loads AND
2. Proper size, design of the geo loop or well you are considering

#1 we deal with all the time, you have plenty of good advice about the problem of oversizing but #2 is the tricky one. This needs a good contractor with knowledge of local soil conditions etc so that the geo loop is designed properly.

On a large job they might drill a test well and test the performance so that you will get the right number but on a small/ res job that would not be economical. So make sure you have a performance spec/ scope that has the contractor guarentee the performance. Be ready to hear that person say " we may just peu in extra to make sure we have it covered.
in today's politiacal climate, I know you might be confused if you heard the truth for a change

[catmanacman]

Pump and dump is a huge waste you will use alot of electricity pumping water .if you drill wells you will also get a 30 % tax credit off the wells

[SkyHeating]

Pump and dump is a huge waste you will use alot of electricity pumping water .if you drill wells you will also get a 30 % tax credit off the wells

Please explain how a water pump on a pump and dump uses more electricity than on a drilled well closed loop.
If both systems are flowing 3 gallons per minute per ton, why would one be harder to pump?

[motoguy128]

Please explain how a water pump on a pump and dump uses more electricity than on a drilled well closed loop.
If both systems are flowing 3 gallons per minute per ton, why would one be harder to pump?

A well often requires a much higher pressure (head) to maintain the same flow rate due to the lift required as well as the length and size of the pipe.

[batman71]

Pump and dump is a huge waste you will use alot of electricity pumping water .if you drill wells you will also get a 30 % tax credit off the wells

Since I have to drill a well for domestic water use anyway, the difference between a "pump-and-dump" and a closed loop system is about $6,000.. I can pump a helluva lot of well water for $6,000!

With regard to the tax deduction, I've got news for you....I will be taking a 30% tax credit for the well drilled for the open loop system. It's all a matter of interpretation of the tax code. Until our friends in Washington decide to simplify the tax code so that it is clear and understandablke, I will continue to interpret in my favor.

I do acknowledge that it will cost more to pump 3 GPM from 75 ft. below the surface than it is to pump 3 GPM thru a loop that is essentially horizontal. But, with constant 56 degree water there are some efficiency advantages of the open loop system that will offset some of the extra pumping costs.
In our area, we are blessed with some very good aquifers. To those who argue that it is not "green" to pump-and-dump, recognize that water dumped back into the adjacent river will find it's way back to the aquifer.

BTW, I would like to thank all of you who are paying for 30% of my HVAC system through your tax dollars. i really do appreciate that. Of course, I have personally been paying income taxes for 46 continuous years now, starting from age 13.

[dan sw fl]

Since I have to drill a well for domestic water use anyway, the difference between a "pump-and-dump" and a closed loop system is about $6,000.. I can pump a helluva lot of well water for $6,000!

I do acknowledge that it will cost more to pump 3 GPM from 75 ft. below the surface than it is to pump 3 GPM thru a loop that is essentially horizontal. But, with constant 56 degree water there are some efficiency advantages of the open loop system that will offset some of the extra pumping costs.

In our area, we are blessed with some very good aquifers.
To those who argue that it is not "green" to pump-and-dump, recognize that water dumped back into the adjacent river will find it's way back to the aquifer.

What are the chances of running a 75-foot deep well DRY at 12 GPM / 700 Gallons per hour / 7,000 Gallons per Day / 200,000 Gallons per month?
Who knows how many gallons a year or decade?


Although quite small, It can not just be assumed as negligible.
Very good aquifer tapped at 75 foot is not exactly equal to Infinite.
How many neighbors within a reasonable distance would be tapping the same source?

[motoguy128]

BTW, I would like to thank all of you who are paying for 30% of my HVAC system through your tax dollars. i really do appreciate that. Of course, I have personally been paying income taxes for 46 continuous years now, starting from age 13.

Then again... since the national debt has grown substantially over that period, one might argue that you haven't paid your fair share and simply deferred your obiligations onto later generations. The same problem exists with pension plans and social security.

I appreciate the recognition that there is not free lunch and where the money comes from.

I never had a problem with pump and dump if it's economical. At my work, water use is so large and water rates are so cheap because of the large useage, we use city water for a lot of cooling applications. SOme of it we reclaim when economical to ru na 1/2 mil or more of piping. But much of it goes down the drain, and eventually back to the river where it came from. We probably average around 150-200GPM combined annually with 15-20 AC units set-up this way.

[batman71]

What are the chances of running a 75-foot deep well DRY at 12 GPM / 700 Gallons per hour / 7,000 Gallons per Day / 200,000 Gallons per month?
Who knows how many gallons a year or decade?


Although quite small, It can not just be assumed as negligible.
Very good aquifer tapped at 75 foot is not exactly equal to Infinite.
How many neighbors within a reasonable distance would be tapping the same source?

The well depth is 162 ft. and the water level is at 55 ft. I used 75 ft. when referring to the head for pumping water.

Admittedly, there are no guarantees with regard to the long term adequacy of the well. I've had enough conversations with well drillers to know that it is VERY unpredictable. They told stories about getting a well producing less than 10 GPM and then drilling a well for a neighbor less than 100' away producing 50+ GPM.

Me and my neighbors are all on 10 acre lots. Are they all tapping into the same sousce as me? No way to know. I do know from reviewing the database on wells maintained by the State of Ohio that mine is one of the deeper wells in the neighborhood. Hopefully that will provide some additional insurance against running out. Maybe I should be more concerned about the local tomato cannery or other industrial users who are pumping hundreds of thousands of gallons per day.

[batman71]

Motoguy128 wrote..."one might argue that you haven't paid your fair share and simply deferred your obiligations onto later generations."

There is no argument from me that, as a country, we have "kicked the can down the road" and saddled future generations with massive debt to pay for things that we should have never spent money on.

And, I suppose that someone could question whether I have paid my fair share. Since "paying a fair share" is a popular topic in the political arena, I wish one of the people arguing that some should pay more would define "fair share".

For 2009, the top 1% as measured by income paid 37% of the total personal federal income taxes. For the top 5% it is 60%. Conversely, the bottom 50% are paying 2% of the taxes. I have above average income but I am far from being in that top 5%. Nevertheless, I believe that the high income earners are already paying a "fair share". Rather than tapping into these people for even more, it is time that this country (and states) cut spending.

One recent example...here in Ohio we have 600,000 who are getting free cell phones thanks to me and my fellow taxpayers. I will guarantee you that many of these people are spending money on goods and services that I choose not to have such as cable TV, lottery tickets, etc. This stuff has got to stop.....

[energy star]

If you have a pump and dump system, in our state the water condition is very corrosive, so all well water must be treated. Once treated, you cannot dump back into another well. Can you in your state?

[tedkidd]

A well often requires a much higher pressure (head) to maintain the same flow rate due to the lift required as well as the length and size of the pipe.

...and it would be wise to use distiller water. You don't want your very expensive mod heat pump scaling up every 3 months, do you?

Pump n dump is short term cheap, long term expensive.

Maybe you might consider air source if you are at the deep end of your capital resources. Your sized house, if you build it well will not require much energy therefore it could take forever to justify the incremental investment, complexity, and let's not forget risk.

Say a good air source system costs $800 a year to operate, and your geo costs $700, percentage wise that's a big difference, but pure dollars is it really worth it?

[batman71]

If you have a pump and dump system, in our state the water condition is very corrosive, so all well water must be treated. Once treated, you cannot dump back into another well. Can you in your state?

In our neck of the woods, the water quality is not an issue. Thre will be some hardness to deal with but the contractors have told me that cleaning the heat exchanger every year or so should be sufficient. BTW, my lot is on a river and I have have cleared it with the local water resource authorities to dump into the river.

[batman71]

...and it would be wise to use distiller water. You don't want your very expensive mod heat pump scaling up every 3 months, do you?

Pump n dump is short term cheap, long term expensive.

Maybe you might consider air source if you are at the deep end of your capital resources. Your sized house, if you build it well will not require much energy therefore it could take forever to justify the incremental investment, complexity, and let's not forget risk.

Say a good air source system costs $800 a year to operate, and your geo costs $700, percentage wise that's a big difference, but pure dollars is it really worth it?

I just sold a house with air-to-air HP/Propane backup and although it was a fine system, I am uncomfortable with future costs of LP gas (too expensive and volatile) and electric is not much better. Here in Ohio, most of our power comes from coal fired plants and the current White House is putting serious pressure on these plants to clean up their stacks which will cost consumers lots of money in the end. If I go with geothermal, I can substantially reduce or eliminate entirely the reliance on either LP or electric for backup. You say that pump-and-dump geothermal is "long term expensive". I submit to you that air-to-air HP is long term expensive!

The net installation cost for pump-and-dump geo after the 30% tax credit is comparable to the cost of air-to-air HP (with no tax credit). Estimated annual savings is about $800 to $1,000 per year, a far cry from the $100 per year difference you used in you example above. So, explain to me again why I would want to go with an air-to-air HP ?

[dan sw fl]

...and it would be wise to use distiller water. You don't want your very expensive mod heat pump scaling up every 3 months, do u.

Isolate with plate HX and eliminate the scaling on the heat pump.

http://www.tranter.com/literature/pr...-and-frame.pdf

[SkyHeating]

Maybe you might consider air source if you are at the deep end of your capital resources.

Say a good air source system costs $800 a year to operate, and your geo costs $700, percentage wise that's a big difference, but pure dollars is it really worth it?

Why does this argument always come up regarding air source vs ground source! It's really comparing apples to oranges and cost is savings per year is one SMALL part of the equation. Geo should last longer, no unit outside, replacement cost should be less since the loop stays. Geo has not outdoor unit noise, it is a greener technology, it also saves in hot water costs so there is another $100-$400 depending on use/setup.

There are more benefits of geo than just cost savings, it's like saying lets get a car that only gets 50MPG and will save $100 per year in gas costs, almost everybody buys cars based on looks and features and amenities. MPG is only a small part of car buying so why is it always the only thing brought up when comparing air source to geo.

Just FYI I can't see any geo saving only $100 more than air source if a desuperheater is installed.

[energy star]

The net installation cost for pump-and-dump geo after the 30% tax credit is comparable to the cost of air-to-air HP (with no tax credit). Estimated annual savings is about $800 to $1,000 per year, a far cry from the $100 per year difference you used in you example above. So, explain to me again why I would want to go with an air-to-air HP ?

No it is not. Any geo system will cost you substantially more than high SEER air to air. AND......did you get a quote to clean out that heat exchanger every year? Just want you to consider all procedures and costs before jumping on the boat...

[tedkidd]

Hey, you are emotionally committed to GS. That's fine. But guys telling you all the money you are going to save, and that pumping is nbd, they have any accountability for results? Their compensation depend upon your decision?

And $1000 a year savings?! They wouldn't have any reason to exaggerate savings, would they?

Do some math. GSHP will NOT save 50% against an inverter driven as hp. Even if it did, to save $1000 at 50% would require your NEW house cost at least 2000 per year to heat and cool, which would require you built a really crappy house. You'd almost have to purposely build it crappy. And why would you do that?

So buy it because it's cool (it definitely is), or any other reason other than the big energy savings, because that's fiction. And the pumping head thing bears looking into.

[dan sw fl]

And $1000 a year savings?!
They wouldn't have any reason to exaggerate savings, would they?

Do some math.

GSHP will NOT save 50% against an inverter driven as hp.
Even if it did, to save $1000 at 50% would require your NEW house cost at least 2000 per year to heat and cool, which would require you built a really crappy house.
You'd almost have to purposely build it crappy.
And why would you do that?

So buy it because it's cool (it definitely is), or any other reason other than the big energy savings,
because that's fiction..

Mentioning Fiction : AND WHY do you Continually speak totally out-of-place without any real knowledge of the Specifc Facts?

Given A well-built R-40 ceiling R-20 walls, 5,000 Sq. Foot house with nearly 1,000 Sq Feet of glass, the total energy cost are definitely going to cost well over $2,000
with a conventional 13 SEER / 8.4 HSPF system when electric rates are > $0.10/ kw-h.
Heating alone will be > $1,800 in a region with 6,000 cooling degree days and $0.10 / kW-hr.

[tedkidd]

Dan, do you see actual consumption, or design? How many actual energy bills have you seen? I'd say Ohio is pretty close to my climate, a lot closer than yours, and I've seen hundreds.

This house at 3200 sf (not 5000) should have a TOTAL monthly bill in the $120-200 range. Heating and cooling will be 1/2 of that. Less than half if built well. Less than 1/3 if he's using that high zoot modulating climatemaster.

I have clients with 1800 sf MOBILE HOMES with TOTAL gas consumption less than 650 therms. That's WITHOUT modulating equipment. You are saying this house will use as many btu as 3 of these? They aren't going to build better than a 20 year old double wide?