Hi, I live in Grand Prairie, which is a suburb of Dallas Texas. I have been thinking of having a water well drilled for years. Now, that I'm considering putting in a GT system, I'm wondering if I can have an open loop water well that I can use for both irrigation and Geothermal cooling/heating. I realize that I would need a second well for the return of surplus water to the aquifer (which is 300-350 feet down). What kind of additional maintenance would be required as a result of the mineral content of the well water?

High mineral contents make return wells dicey at best. Depending on your requirements however 2 wells might be close to what you need for closed loop.
The best people to answer your questions are local well drillers.

Hey Joe, thank you for the reply. So, I'm kind of at the point where I'm not sure what questions to ask. I live in a 30+ year old house. It was build with a 3 ton conventional air conditioner. But on the hottest days, it would never cut off. So when I replace it, a few years back, I went with a 4 ton, 12 seer unit that has served me well. From the reading I have been doing, I'm thinking I would need 4 vertical 300 foot wells to supply the 4 tons of cooling requirements for my house. Being from the south, I'm talking cooling requirements, rather than heating. I currently have a NG furnace (air handler) that I will likely keep. So, I'm thinking of a split GeoThermal heat pump system. I'm comfortable with the HVAC part, because I have been doing it for years. But the Ground Loop Design is where I will need some assistance. This looks like a great forum to help get me started in the right direction.

I live in a 30+ year old house.

Have you looked into energy saving insulation or window upgrades that might actually reduce the cooling load of the house as opposed to spending more on a bigger air conditioner?

So, was there a question with that last rant you ask? Well, I think so. I'm still trying to evaluate the feasibility of an open loop system. I currently spend as much on water as I do for electric. Yea, go figure... So it would be great if I could kill two birds with one stone. But I don't want to get into a maintenance nightmare. Does anyone on the forum have experience with open loop systems? If so, would you mind sharing your experience?

Thank you,
Scott

Wow, so this thing eats paragraphs?

I agree with ICF on load mitigation first. Your best bet is to find a local geo well driller. Try the IGSHPA web site for certified vertical loop installers in your area. Many don't sell equipment and would be happy to work with a DIY guy.

Hi ICFHybrid,

I have added insulation to my attic twice. It is stealed about as good as possible. I still have the seven original single pane windows that I should replace. But I have low motivation since none of them get direct sun light through them. Well, I do have one that gets winter sun, and I love it. I will replace them, but really don't expect to see much difference in my cooling bill.

I have put in calls to a couple local well drillers. Interestingly, they don't even bother to return my calls. I guess they have more work than they know what to do with. Thank you for the recommendation, I will check out the IGSHPA site.

What little I know about open loop:

Get your water volume for the heat pump at the lowest pressure possible and

secondarily, boost the pressure as needed for domestic.

Corrosion and fouling deposits requiring additional maintenance will be an issue at the heat exchanger at the top of the open loop, even with check valves to hold pressure when the system is off. Titanium HX is recommended.

Delta T on open loops are greater. Pumping costs are greater than on closed loops.

experts?

I will replace them, but really don't expect to see much difference in my cooling bill.

The R-value of new windows should be much better than the originals and it will actually help. Casement and awning windows seal much better than single or double hung. How about sealing the home against air infiltration or insulating the walls? Also, the next time a roof is called for, a "cool" color might be preferable.

The only way o get at the question of maintanace is to know the water quality you will be using. If it fits the unit chart you are clear for take off. How large is your irrigation system potentially going to be? Water can be used for btu's first then for irrigation, mitigating the recharge well issue. Just a thought.
Eric

Air infiltration makes a even bigger difference for cooling because of latent load. So I would have a blower door test + more sealing done.

Indeed. Did any of the folks who insulated the attic do a blower door test?

Did any of the folks who insulated the attic do a blower door test?

Why do a blower door test when it's done "as good as possible" in the first place?

> Why do a blower door test when it's done "as good as possible" in the first place?

Because in this case, it was done "ABOUT as good as possible", which can be quite a different thing.

which can be quite a different thing.

Heh heh. Glad you caught that.

t580012,

You indicate the 3 Ton you had never cut off on the hottest days. That statement alone does not rule out a 3 ton. The question becomes whether the 3 ton was able to maintain the house at the thermostat setpoint. If on the hottest days it did, then the 3 ton may be just what the doctor ordered. Continuous run is not a bad thing if it meets the load requirement. Less cycling of your plant equipment can be beneficial.

Trent

Posted By mtrentw on 16 Sep 2013 12:22 PM
You indicate the 3 Ton you had never cut off on the hottest days.
That statement alone does not rule out a 3 ton.

Correct. Also be aware that "3 Ton" is just a nominal rating -- for a
specific set of operating conditions. So, depending on your actual
conditions, a "3 Ton" ground source heat pump might have more
cooling capacity than a "3 Ton" conventional A/C ...or maybe less.

You need an HVAC professional with Geo experience to make that call...

...that's why they get paid the medium bucks,

Looby

Also be aware that "3 Ton" is just a nominal rating -- for a specific set of operating conditions....You need an HVAC professional with Geo experience to make that call...

Or just read the manufacturer charts (edit: we are talking about open loop). Wasn't long ago that that one of the "professionals" here was unable to use the nominal and actual terms.

Less cycling of your plant equipment can be beneficial.

It would be interesting to see a cost analysis, especially in the case of inverter units where 1) a bigger unit has heat exchangers that run at greater part-load efficiency, 2) an oversized unit can still run continuously and 3) lower rpms or fewer hours should lead to longer compressor life.

This has some water quality guidelines for open loop, although it depends on how often you are willing to clean the heat exchanger. For example, automated acid flushes might allow the use of very hard water.

"...that's why they get paid the medium bucks, ".....LOL don't sugar coat it kid, tell us how you really feel. Funny with the way we alledgedly gouge everyone I oughta be in the big bucks right?

"For example, automated acid flushes might allow the use of very hard water." As an added bonus they may void your warranties.