Is anyone really certain the well pump is any good? Maybe the foot valve is somewhat stuck shut. Just a guess.
I just purchased a new home (it was a bank owned so it's about 200% more house than I would normally afford) It has 2 Geothermal units (5 ton and 3 ton)
Best I can tell the 3 ton cools the lower level (so almost never needed) and the 5 ton cools the rest of the house.
Open loop system and (pulls from well dumps into creek) talking to the original owner (now 2 sales removed so no reason to lie) he said the well would deliver 20GPM 24/7/365.
Talked to the guy who installed the pump (a 20GPM Grundas I believe) he said the pump could run full bore and never drop the water level.
The house sat unused for about 3+ years. Well only produces 6gpm now.
well is here:
Aquifer Type: LIMESTONE
Total Depth(ft): 160
Test Rate(gpm): 15
Static Water Level(Ft): 60
Now, the local well guy said "Well the problem is that the well is too deep, they probably hit water in the sand at 70-90ft and then kept drilling to the limestone, they used a solid casing so when the well was being used the water ran down the outside of the casing and into the bottom of the well. After disuse the paths down the side of the casing probably got filled with sediment. So they came out and fitted a valve on the wellhead and put 50lbs of dry ice in the well and sealed it (hoping to "reopen" the channels to the water.)
To no avail, still 6GPM. "Yep that's what you're getting from the rock, you need another well to get to the water in the sand"
So I'm having a second well dug, hopfully it will be 12GPM+ but if the well is dry/only does 2GPMetc, is there any way to use that as some kind of reclamation/discharge well?
If not now I've got a well and a vertical hole, if I drill one more well can't I make some kind of semi-closed loop system? (ie pipe my hot exhaust water through the two deep wells for cooling and put back into the system?)
I'm at a total loss here, I bought my dream home but the cost of getting the geothermal to work might mean I have to sell the place. And it's 6000sqft so there's no way I can afford to heat/cool with a conventional system. No one wants to talk to me about options, the only option is "Drill another well". I lucked out into getting $25/ft for the new well. (Of course ohio screws you for $1K for a permit "just because we can")
What are my options/good fallbacks thoughts etc...?
Again, any help GREATLY appreciated.
Is anyone really certain the well pump is any good? Maybe the foot valve is somewhat stuck shut. Just a guess.
You may want to cross-post your question on this forum, which has a number of geo-pros actively posting.
The average state of industry for the ground-source heat pump system design/implementation by installers is pretty abyssmal, and it may be worth re-commissioning the system under the guidance of a competent designer who does the math. The as-installed average efficiency for most systems is well below the "best-practices", and poor implementation can use literally twice the power of a pretty-good implementation based on the same core equipment. The fact that you have a combined 8 tons of compressor in a residential application does not indicate a good design, even if it's a pretty big house. Most reasonably tight houses in any Ohio climate would have true design-condition heat loads of half that. Even using 1000 square feet of living space/cooling-ton as a rule of thumb (overkill for newer homes with decent insulation and windows unless the home is in Texas or Hell :-) ) it seems a bit much.
The first thing I would do is check the pumping level in the well. If the water level pulls down to the pump, it is a well problem. If the water level doesn’t pull down, it is a pump problem. The pump could be bad, or just running backwards (3 phase?). The pump screen could be plugged, or the check valve stuck. If for any reason you can’t pull the water level down, it is a pump problem, not the fault of the well.
If the water level does pull down, then the well is not producing as it should. If it has steel casing, the screen maybe just rusted up after sitting for three years. I wouldn’t count on dry ice by itself doing any good. You can contact Cotey Chemical in Lubbock, Texas. They make chemicals that can clean up the well and casing. I have seen their stuff make good wells when the owner thought it was a dry hole.
Those wells would need to have some really good underground flow to be able to use them for a closed loop. Probably going to need a bunch of holes drilled to make a closed loop system. This is why many drillers will tell you an open loop system is not as efficient as a closed loop system. They want to drill you $30,000 to $50,000 worth of wells for a closed loop system. Open loop system can be even more efficient than closed loop systems, and only require one or two wells at most.
If all else fails and you only have 6 GPM, you can do a lot with that. I have a 3 ton system that does quite well with the 4 GPM that I have available. If you can get another 6 GPM well, you might be able to make the two well set up work with what you have like in the following link.
Last edited by valveman; 08-05-2012 at 05:57 PM.
I just had a second well drilled on the reccomendation of the local well companies (go figure).
2nd well is 30ft west of the 1st well and it only provides 6gpm.
Sooooo.... Now I'm in a good pickle. Wells cost about $5K each.
I have 2 wells delivering 6 GPM each, One is used for my "house needs" the other is just,..there.
I need 13GPM for running all geothermal. If it had been working it would have been running non-stop for the past 2 weeks I'm guessing (103 temps) so worst case scenario would be that I would need them both running for extended periods.
I need 4-6GPM for running "household needs"
So I really need 18-20GMP fixed to cover all my bases.
Just reading the forums, making it a closed loop vertical is out of the question as I'd need another 8 wells ($40K no way!)
Horizonal is out of the question as I have a VERY small footprint on which I can drill (1000 sqft ish total)
Isn't there some way I can "recycle" the geothermal water??
My thought is if I have 2 wells, and I pull cold water from well 1, run it through the system then dump it back into well 2 (with a pump at the bottom moving water back to well 1) would the 6gpm of new cool water in each well plus the temp loss of getting to/going down the well chill it enough to move to well 1??
There is no one in my area that wants to deal with this as these two units were put in and are brand new by some company out of state. (so they can't sell me new ones and don't get the warranty work either, there's always going to be plenty of low hanging fruit before they get to me, and the well digging guys are 100% no help, it took 2months to get someone out for this well.
If that doesn't work I'm going to have to drill a 3rd and 4th well (praying that they won't effect each other if they're far enough apart) so I can pool them up to get my Geothermal up and running.
(so two new wells @ 5K, 2K in pumps and hookups additional piping etc.. etc.. so a 30K project when all is said and done that I didn't see in my future.)
The one small bit of luck was that I didn't have to shell out $1k for the permit as this new well would be geothermal only.
Again,..any help would be appreciated, the locals don't want to touch this project so I'm on my own this time.
This is interesting but I'm not sure how it would work for me,...If I was runing geothermal constantly (say summer deep winter) I would still be "Drawing 13GPM" for an extended period of time and that's before a shower/dishwasher etc... If I had a 3rd well I think it would work (two wells trading off for geothermal, one well for household needs)
The new well (see my latest post) is PVC with screen and has the exact same results, so it looks like whatever was suppling all that 20GPM water for the 30years prior is just "gone" now, 6GPM is the best I'm going to get from any well on my property.
Also the pump is 100% I had it cleaned and tested with a known good source, it will pump 20GPM all day with no problems.
So at this point everything seems to be 100% but the wells, they just don't produce.
Again, it's doubtful that your true cooling or heating loads are anything like 8 tons. Most new-construction homes in OH would be on the order of 3 tons. Even if your house has is a 5000' Manse, heating & cooling loads don't scale with floor area- it's much less than a linear function. The larger the house the lower the ratio of floor area to load. ANY home built to code in OH within the past decade will have a heating load well under 96,000BTU/hr (8 tons), and very few would be over 4 tons (48,000BTU/hr.)
I suspect the system can be cost effectively modified and recommissioned to run both floors/zone with only one of the heat pumps, which would lower your gpm-max needs. With a careful heat load calculation based on a realistic 99% outdoor design temperature for your location would give you a feel for whether it's better to try to run it off the 5 ton vs. the 3 ton pump. I'm sure you can find competent energy-use consultants or HVAC pros willing to do a careful heat load analysis for a fee. They might nick you a few hundred for their time, but it could save you thousands by giving you the right output targets for your GSHP system.
At $5K/pop you can end up spending a lot of money poking holes in the ground to get the flow rate up to what you need for 8 tons, and if you don't need anything like 8 tons (as is almost certainly the case) it's money wasted. If the calculated load load is 3.5-4 tons may be able can lower the load to 3 tons with judicious modifications to the house for less money than getting the flow required for the full 8 tons (with no guarantee of continued flow rate, given that the original wells are running slower.) There's no operating cost to the missing load tonnage- it's all pure comfort, whereas there IS an operating cost to the larger sized GSHP, so even if it costs a bit more to bring the load in range, it's usually worth it.
The other thing to consider is, if auxillary resistance heating could be used to make up the difference at the cold temperature extremes even if the heat load was 45K, 3 ton would be carrying vast majority of the heating, since most of the winter the load is fully within the output capacity of a 3 ton unit. Average heat loads are on the order of half or less that of the 99% design peak. Depending on your utility rates it could take many years or even decades of aux-heat use to add up to the cost of what it takes to bring the geo up to handling the full load. Many designers who have an eye toward lifecycle cost will spec the geo at only 80%-90% of the design condition heat load. And many of the people living in those houses will opt to disable the aux heating strips, and only get uncomfortably cool once per decade, or turn down a less-occupied zone during the decade-extreme cold snaps so the rest of the house will stay 70F.
Again, try posting the details of your to that forum I linked to in my first post. There are a handful of GSHP pros posting there willing to look at the details and provide practical advice on the most cost-effective (and effective) solutions.
With the two wells working together you have 12 GPM. You should be able to run both heat pumps with this if needed. The house will be a very small load in comparison. I use the discharge of my heat pump to feed the house. That way the house doesn’t add to the GPM required. But it does mean the temperature of the house water will vary with the discharge temp of the heat pump. With a heating load it just means the water coming in the house will be a little cooler, and a little warmer with AC load, but few of my guest have even noticed.
Running water for the house through the heat exchanger when the heat pump is not on has even helped keep my heat exchanger clean. I haven’t had to clean the heat exchanger in over five years I have had this system.
Another option is to use a small, maybe 1,000 gallon storage tank with a booster pump just for the house. The discharge from the heat pump can run through this tank keeping it topped off all the time. Or you can feed it with a ½ GPM bleed from the main line without effecting the flow to the heat pump very much.
Of course anyway you do this the pumps are going to be required to operate at varied flow rates. So a Cycle Stop Valve on each pump, as well as the booster pump if you go that way, will allow the pumps flow to match the amount you are using without cycling the pumps on and off until they die.
I can draw this up for you but it will be similar to this drawing except there will be two pumps feeding the system and a storage tank before the booster pump..
Since you already have two pumps in two wells, and only one is permitted for the house, this is what I would do.
I would put a CSV and small pressure tank on the well permitted for the house, and run a water line to feed the house. I would also tee off this line and go to a 1,000 or 1,500 gallon storage tank. Put an electric solenoid valve with a flow control knob adjusted to 6 GPM on this line going into the storage tank, and control the electric valve with a float switch. Put this float switch a foot or two below another float switch.
Use the higher of the two float switches to control the new well permitted for the Geo system. Run a water line from the new well directly to the cistern, and restrict it to 6 GPM with a ball valve.
Now the new well will try to keep the cistern full. But if it can’t keep up, the water drops to the lower float switch, opens the electric solenoid valve, and the house well comes on and starts adding another 6 GPM to the cistern.
Put a reverse acting pressure switch on the water line coming from the house well. Loop the wire from the lower float switch through this reverse acting pressure switch. This way when you need water in the house, the pressure will drop and this reverse acting pressure switch will close the electric solenoid valve filling the cistern tank. When you are no longer using water in the house, the pressure will increase and this switch will again open the electric solenoid so the house well can help fill the cistern tank again.
Then all you need is a small little circulator pump drawing from the cistern storage tank to feed the heat pump. You could also have the smallest pump possible in the new well for the Geo system, because it no longer has to build pressure, just put 6 GPM into the cistern storage tank. Keeping the size of these two pumps as small as possible will save a lot of pumping cost for the heat pump. You can use a UP26-99F Grundfos which is only 1/12th of a HP to feed the entire Geo system. Then a little 1/3 HP pump in the new well will also keep the pumping cost down.
Using the pumps you already have in the wells, I can see less than $1500 cost for the storage tank, electric valve, float switches, CSV, even the 1/12th HP pump for the heat pump.
The theory is if you need 13+ GPM some of the time and only have 12 GPM available from the two wells, the storage tank will create a buffer that refills during off peak hours.
I can draw this up and help with wiring diagrams if you would like, just let me know.
The house is 5900Sqft with tons of windows, and skylights.
I have heat strips installed on both units, and 3 fireplaces so heating isn't as big an issue as the cooling is. (and/or the issues of running pumps/wells/system dry etc..) Unfortunatley I have a lung condition so 90+ days can cause me serious problems if the humidity is up. Thanks for the link, I cross posted and will look for info.
The biggest issue that I'm running into at this point is that I've put every dime I have into this place, and now I can't move in because I can't cool the house on a hot day. Needless to say more wells/pumps/etc.. are $$'s I just don't have now. Fall hopefully is around the corner so that won't be a worry soon, but the geothermal still needs water flow to heat, else I'll have busted pipes (and/or a electric bill I can't afford if I'm running off the strips all the time) so I still have concerns.
My only concern with this setup is that this summer I would have been running almost 24/7 with cooling on at a VERY high rate (don't know what drawdown would be and/or if I could replenish fast enough.
I hope the well test shows that you can run 6 GPM from each well. That would give you 12 GPM, and if you need 13 GPM to keep the heat pump happy, the bleed back idea is a good one. I don't know if you could dump back into the potable well, but you could in the geo well. Get 6 GPM from the potable well and 7 GPM from the Geo well by dumping 1 GPM of water back into the Geo well. It might make the water from the Geo well a tiny bit warmer, but a heat pump can make AC with fairly warm water, it just needs enough flow.
I second the dump-back solution as the likely most-cost-effective solution.
With a lot of unshaded window & skylight the cooling load driving the system sizing, but the peak loads are well above the average load, and a dump-back scheme should work without a significant hit in system efficiency or capacity given the relatively cool deep-soil temps in your area.
If your concern is primarily humidity, hire an insulation company specializing in air-sealing to tighten up the air leakage on the place. Latent load (humidity) is a function of ventilation rate, and in air-leaky houses the uncontrolled ventilation rates can be extremely high. In a low-occupancy residence the ventilation rates do not need to be very high to maintain indoor air quality, but are best done with very tight house and an energy recovery ventilation (ERV) system. If your house doesn't have an ERV, it's still almost impossible to retrofit-tighten the house where that would be absolutely required, but the air-sealing contractor would be able to estimate that at the time they verify their work with the blower-door testing.
I think at this point I'll look at dumping "some" of the output back into well 2 and looking at some kind of intermediary storage tank for house water
So (let me see if I have my head around this)
I'd pull water from the tank for house stuff, if the system was running full out it would use both wells and some of it's own output and run 100% both units and start depleting the tank. When the system is "off" the wells are recharging and when they top off one dumps into the "house use" tank for later use.
So,.... I guess I need a well pump for well 2, a storage tank, backhoe to burry it, pump for tank, lots of PVC, some kind of sensors/switches to tell me when tank is depleted, wells are full, etc.. etc.. and do all the appropriate changeovers and a heat exchanger on the wastewater before re-introduction. And I think that should solve the problem. Then if the draught lets up and the wells produce more I'll just have less worry/recharge time.
Does that sound solid?