well water which means I am less likely to run my well down or create problems
for the neighbors.
As an odd side note, the distributor would not tell us what size pump in
horsepower, gpm, and at what depth to place the pump in our well UNTIL
they had a signed purchase order for their equipment. I could not figure
out why I would get such an unfriendly reaction to my request for this
information. Then I wondered, is there a lot of internet sales of
do-it-yourselfer geothermal that goes on? Maybe that is why he would not
tell me what pump I would need for his geo system.
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jimhollander_at_hotgrips_dot email@example.com (hotgrips) wrote in
I have two Tranquility 27's - a 5 ton and a 3 ton for our two-storey
5,000sq ft house up here in Canada. We also have a finished basement with a
walkout so the heating load is high. We use the 5 ton for the first floor,
basement and crawlspace. The 3 ton is for the second floor. We also have an
open loop system. We have used this for 3 winters already. The
Tranquilities are good. Not as silent as advertised - my friend's
WaterFurnace is about the same for noise. The open loop system is terrible
- if I had it to do over I would not have gone open loop and I would not
recommend it - as a matter of fact I strongly recommend against it.
I have had tremendous problems with the injection well over-flowing due to
airlocking. In our case the overflow can drain safely away without causing
any problems - for a while. Open loops are very prone to overflowing and if
your location is such that the overflow would cause problems with neighbors
you will be very sorry. Go to closed loop if it is at all possible. The
open loop is a permanent problem. Well depth doesn't help, our supply well
is 320 feet deep.
You don't mention anything about an injection well - you need one or a
complicated way of using a single well for both supply and injection.
I have received no help at all from our installers with the well problem
and have tried several solutions based on advice from geotechnical
engineers. The installers version overflowed after 2 months, my second
trial worked over the next winter but overflowed after 10 months, my third
trial has worked over the past winter and is in its 9th month with no
overflow. I have done a lot of research on the problem and have determined
why the injection wells overflow so I expect that I will require a 4th
trial to eventually solve the problem.
All groundwater has some air or other gases entrained. The well pump
pressurizes the water and the flow through the system undergoes pressure
losses as it travels - simple physics, there must be losses for there to be
flow. It is these pressure losses that cause the problem - air comes out of
solution whenever there is a drop in pressure as there must be for water to
flow through any system. This air is forced into the ground formation and
eventually causes an air lock. I have had to reverse pump the injection
well twice now to remove the air locks. I would have been much better off
with a closed system.
You should compare the costs of the LP furnace to the cost of a Tranquility
optional electrical auxiliary heating coil unit plus a 400 amp service
upgrade. In our case the electrical has not come on the past 2 winters and
they have been very cold. Nobody up here, in the city, has generators for
backup because our power failures are short duration. In the countryside
power failures are more common and last longer so generators make sense
Your flow rates seem a bit high - I am running about 16-17 USgpm for 8 tons
total. Flow rate must be fairly tightly controlled for an open loop because
it is water, not anti-freeze being pumped. If the flow is too slow then the
heat pumps can suck enough heat from the water that there is a risk of
freezing in the exchanger. If the flow is too high it increases risk of
erosion in the heat exchanger. Our installer set the flow rate so the water
leaving the heat exchanger was no lower than 38 degrees. That leaves a
safety factor against cold spots, etc. Our groundwater is enering at about
46 degrees and the difference supplies us with plenty of heat. Our house is
built to very high insulation and sealing standards with all triple pane
Do not use flow control valves to adjust flow rates through the heat
exchanger. The installer initially used flow controllers on our system and
the well overflowed inside of 2 months. When it was overflowing I could see
a lot of air bubbling up which stopped when I fully opened the valves and
resumed when I reset the valves. Any device that loses pressure will cause
air to come out of solution and cause an air lock. The system has natural
losses that can not be avoided but a control valve operates by deliberately
causing a high pressure loss. The hissing noise that a valve makes is air -
solid water does not hiss. My installers insisted that they always used
these valves and never had a problem anywhere else. I found three other
customers of theirs who had overflowing wells and the engineers tell me
that they solve commercial overflow problems by removing the valves. A year
or two later the customer calls them back because the well is overflowing
again and they find the valves were re-installed. There are other ways to
control flows that don't use valves but the industry does not seem to know
of any - my installers had no ideas at all of how to solve the overflows.
Your best approach would be to use a separate pump for the geothermal. Make
it a variable speed pump and adjust flows by adjusting pump speed. Oversize
all of the piping to minimize pressure losses throughout your system. Make
sure there is no way that overflow from the well could cause a flooding
problem because it will overflow eventually. Do not go to a two heat pump
system if you can help it. I am serving two heat pumps with a single well
pump and the need for flow balancing between different sized heat pumps is
causing significant complications. Most ways of balancing flows cause air
I am looking into air separation devices on my discharge lines and/or a air
separation arrangement inside the injection well.
If you go to closed loop the system will be very much simpler to operate.
Make sure that any contract addresses the risk of the injection well
overflowing and who is responsible for addressing it. Even a guarantee of
fixing overflow problems may be of little help - if your groundwater has a
lower concentration of entrained air then your system may not overflow
until the warranty period expires. You can't tell if there is an air
problem until it overflows and you can see the air bubbles in the water
flowing out of the top of the well. You could measure well moundup with the
pump running but that requires some expertise and there could be the
argument that a change in moundup doesn't necesarily mean it will overflow;
until it does. Also, the installer will blame anything and everything for
the overflow so he doesn't have to fix it. He most likely won't know how to
solve it. Solutions can be expensive and may not work. So what's the use of
a warranty if the supplier doesn't know how to fix it? Have I mentioned
"don't use open loops?!!!"
am familiar with most of the locals in southern NH.
Thank you for such a thorough reply from Canada. That is the kind of
experience that would be very painful at my age of 60. You must be
healthy, young enough to have the energy and drive to carry the project
home to the end. I admire your persistence, many years ago I used to work
long hours and seek to solve problems like that. You write well and you're
well educated. What an experience you are going thru! I am located 2 hours
south of the Canadian border. Could that make the difference. I had the
general knowledge of geothermal systems that the further north you go, the
less efficient they are. I had not heard of a story like yours yet. Have
you come across similar experiences with open-loop systems?
I was steered towards the open-loop well system but do have 15 acres of
high clay-content soil, so it is possible to do a closed-loop system.
However my soil has big heavy rocks and I'm concerned about crushing the
slinky tubing. The soil is too water-saturated to permit truck loads of
clean soil to be brought in. A portable screener won't work because the
clay soil is too wet and dense.
A pond 300 feet away and 30 feet lower exists with a drain valve, but I
was told the water temperature at the bottom would be too cold (14 ft.
depth) and the pond is a bit small at 50 ft x 125 ft. I was told that a
closed-loop ground source system would not be as efficient and not
generate the btu's of an open-loop well system.
I have a 450 ft. deep well with a static level of 20 feet. We pumped out
18000 gallons at 10 gpm to find the level of equilibrium is 55 feet down.
We plan to simply return the water back to the same well, using a 450 ft.
deep 1.5" plastic pipe. The water pump would be located at 100 feet. The
10% bleed water was going to be discarded to a surface rock trench, where
it will percolate into the soil.
Does the much colder Canadian climate present greater challenges to
open-loop geothermal systems? How far north of the US border are you? I
just haven't heard of those kind of problems down here. (New Hampshire
geothermal owners please input to this).
My distributor is Northeast Geo and I understand that they have 30 years
of experience and 12,000 installations. I have their most experienced
state dealer with the most customers in the state. Unfortunately he is 90
miles away so each service call beyond the warranty will cost an
Does your dealer have a track record of successful installations, or did
you find out too late that he is somewhat incompetent? Or do all
open-loop geothermal systems in your latitude have similar nightmare
scenarios? You sound very thorough in your email reply, were you not so
thorough prior to selecting a dealer and the type of system? Or did you
trust the dealer too much and just have an unusually bad run of luck. If
that kind of experience is typical of open-loop systems how can they be
used so much? Are the successful stories found on the internet simply
fabrications from dealers pumping their trade?
Thank you again for the great input, I hope you can solve the problem.
You have given me much to consider.
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I will reply to your questions after snipping a quote from your comments;
I had the general knowledge of geothermal
Geo systems do lose efficiency with drop in incoming water temperature so
that is the reason for a correlation to drop in efficiency with distance
northwards. Also, why your pond idea would be less efficient. Otherwise the
whole system is buried below frost so being farther north should make no
The tubing would have to be in complete contact with the surrounding earth
for efficient transfer of heat from the ground. Backfilling with clay lumps
would leave a lot of air pockets and thus very poor efficiency. I have some
geo manuals from the Oklahoma geothermal institute that state that the
whole pipe should be buried in special thermally efficient grout - gives
complete contact plus protects from rocks in the backfill. I found several
studies that estimated improvement in efficiency of 5 to 10%. I also found
that none of the suppliers of grout in the city had ever ordered in any of
this type of grout. Dry sand or soil has low thermal efficiency so your wet
location would be ideal, thermally, even if you just backfilled with clean
sand to about 6 inches above the tubing to protect it from rocks. Then
maybe pump a lot of water into the backfill to break up lumps and improve
compaction. Don't pound with packers at all or at least not for the first 2
or 3 feet above the tubing.
Open-loop is indeed more efficient than closed loop - that's one reason I
selected it. Major reason was that we are on a sloping clay riverbank that
is at risk of slow sliding movement which would have torn apart buried
Too bad about the rocks - I agree that digging in rocks would be very
Yes, closed loop is less efficient but not that much, maybe 5%. All you do
is use longer length of collector tubing to get the same incoming energy.
So actually, it is not so much less efficient as it simply means you should
design the collector tubing correctly.
I have heard and read about single well installations but they all had one
major difference fom this suggestion - use of a rubber seal to separate the
water coming back from the house from the groundwater flowing into the well
from the formation. The seal forces the incoming water to flow outwards
through the formation before it can get back into the well and thus it
collects heat from the ground along the way. Without a seal the well is
sort of like a 350 ft long vertical heat collector - length from bottom of
well to pump. It is helped considerably by the use of 10% bleed water which
causes that amount of new water to enter from the formation, plus a small
additional amount due to domestic uses. The only new heat comes from water
travelliong the 350 ft plus the heat in the 10% inflow. Thus 90% of the
water is recycyled for more heat transfer. If the incoming heat does not
keep up with the heat extracted by the heat pump then the well water could
freeze. Actually freezing would be prevented by sensors that shut down the
system if temps fall below a pre-set limit or if frost is sensed on the
exchanger. So the system is protected from freeze damage but what happens
then is that the auxiliary heat kicks in and you don't get the benefit of
geothermal efficiency until the temps rise again. I met one couple whose
heating bills were the same as their old house which had gas heat and a
much lower standard of insulation. They gained nothing from their
investment in geothermal. I think their problems were due to the wells
being only about 70 ft apart and at the same depth - water simply flowed
quickly along the short path between the wells which was not long enough to
collect enough heat to keep the geo going. Their red light indicating that
the auxiliary heat was operating stayed on most of each winter. Hopefully
you are not going to get the same performance due to recycling of the same
water which can only supply a certain amount of heat before it is cooled
too low to be useful.
Closed loop systems have anti-freeze in them so they won't freeze and can
be operated close to freezing temp - 32 degrees. I met one installer who
claimed he had a closed loop buried only 3 ft below a parking lot and it
supplied enough heat for a commercial building. I found that hard to
believe as parking lots are kept clean of insulating snow and up here frost
penetrates 8 ft or more under clean pavement. So this system was supplying
heat from a loop that was below freezing temp for most of the winter. The
ClimateMaster manuals do show earth loop temps down to 25 degrees so he may
well have been truthfull. He had photos of the system being installed.
We are in Winnipeg which is only 75 miles north of the border but dead
center of Canada so we get the coldest winter temperatures of the country
going east/west. This winter we had 6 weeks of temps below minus 30 degrees
I am on the second dealer. I researched the first one fairly well and he
came highly recommended by my project managers who had used him on several
jobs. I checked on two of his jobs and the workmanship was impecable.
Unfortunately something was wrong with him on, I think, a personal level.
He refused to showup when we needed him and delayed construction by at
least 6 weeks because we kept believing his promises to come 'next week'.
He then started demanding tens of thousands of dollars for 'progress
payments'. We had paid him $5,000 down and I told him progress payments
would be after progress was shown, not before. Then the police and tax
collectors showed up looking for him and garnisheeing any future payments
we might have made to him. Turns out he had collected much money in down
payments from many people and never showed up and was way behind on his
taxes. I fired him. He had already finished the wells, the well connections
and the ducting for the second floor of the house so I think we only lost
about $2,000 on the guy, compared to $10,000 and $20,000 losses the police
told us he had taken others for. It was a shame because he was a nice
person who had done great work in the past. The second installer naturally
took no responsibility for the wells because he had not installed them. His
warranty only covers his own work which is perfectly reasonable. It does
leave me holding the bag for anything well related.
The second installers were the ones who insisted on use of pressure
reducing valves (PRV's) despite my insistence that they would lead to air
locking based on opinions from two professional geotech engineers. The
installer said if the wells air locked they would come back and remove
them. The well did air lock by Christmas of the first winter, 2 months of
heating. The large air bubbles came and went with turning the PRV's on or
off, proving that they were the cause of the air. The installer agreed but
had no idea of what Plan B should be. I suggested we use a separate
discharge line for each heat pump and put orifices on the ends to restrict
flows to the required levels. This was done but they sent me a bill for
$2,200 for 'improvements'. I said they were not improvements but
corrections to their instalation. Considerable polite discussion ensued.
They reduced the bill by half and that was the best they would do. I paid
it. That mod lasted through one winter but overflowed again. I did Plan C
myself. I now know why it it overflowing and think that either an air
separator (degas vessel as suggested by another poster) may help or I have
another separator idea. Plan D should work to 90% or better success.
The problem with air entrainment is if it is reduced but not eliminated
entirely the solutions become much more difficult and expensive. The large
bubbles of the PRV's air locked in 2 months but I solved it with 5 hours of
reverse pumping of the injection well which drew the air out of the rock
formations. Plan B overflowed in 10 months but it had very tiny bubbles (1
mm in dia). The small bubbles travelled farther into the rock formations
and were very difficult to remove. I reverse pumped for 2 weeks with
negligible improvement. I then acid treated the well which blew up like
crazy but removed all the air plus improved capacity even better than
original. Took me 2 weeks of pumping plus a day of setting up the acid
program and performing it and then cleaning up the mess from the blow off.
Cost $300 for acid and parts and at least 4 days of my time. Also killed
some grass that must be re-sodded. I borrowed an expensive acid pump and a
lot of fittings. This would have cost a normal consumer quite a bit from a
If my Plan D leaves only a few miniscule air bubbles it may not over flow
for years but when it does the air will have gotten so far into the ground
formations that removing them by reverse pumping will be impossible and I
will again have to acid treat. Acid is very dangerous to handle and when I
get into my 70's (15 years from now) I won't be able to do it alone. Have
to train the boys or someone younger but for now I don't want bystanders.
Or do all
I've found 3 other homeowners with over flowing wells. My geotech friends
do about 3 commercial jobs a year to correct over flowing wells. They also
get monthly or maybe bi-monthly calls from private residents with
overflowing wells who can't afford to hire professional consultants. So
they are not uncommon.
I did do a lot of research ahead of time but all I got is answers to my
questions. If you don't ask the right questions you don't get the right
answers. So I didn't research problems with open loops until I had
problems. I didn't researche air locking when I was comparing open loops to
closed loops. Then I got no end of hits about air locking and mineral
deposition, photos of wells that were essentially lined with rocky mineral
deposits until they were unsalvagable, etc, etc. My problems seemed minor
compared to a lot of others. All reports say 'maintenance' of wells, like
any other piece of equipment, is required 'for proper operation'. But what
the heck is well maintenance? The geo companies lead you to believe that
you may have to replace a pump every now and then. Simple and cheap and
everyone knows well pumps last a long time. They don't tell you that when
wells get air locked the pressure drops in the system also cause mineral
deposition inside of the heat exchangers, piping and injection wells.
Commercial installations are advised to use multiple injection wells so
problems are slower to appear and some wells can be used while others are
treated. Advice includes cautions that the injection wells may have to be
abandoned and new ones drilled. The new ones may have to be far removed
from the old ones because mineral deposits may have plugged up a good
region near the old wells. Thus you have expenses of new wells and longer
connections, assuming you have the land to drill new wells.
If that kind of experience is typical of open-loop systems how
That's exactly what I am wondering. The professional engineers i know have
little respect for the geothermal companies around here. My problems are a
constant source of amesement and 'why would any sane person use open
loops?' 'Why didn't you ask us first, we could have told you it wouldn't
work.' When I consulted them at the beginning they were not eager to bad
mouth the industry but then they have had 3 years of bad
experiences/observations since then and are now less shy.
I've been too busy fixing wells and trying to make a living to get back to
the folks who told me their wells were also over flowing. One guy said he
can't afford to fix it and will just let it over flow into a ditch where it
seems to infiltrate away. Haven't heard from the others. Most of the people
I have contacted with geothermal heating have closed loop systems - the
closed loop people are all happy, no exceptions.
I think open loop can be successfull if the groundwater has very low air
entrainment and low mineral content - ours is high for both. You should get
water tests done at a commercial lab and show the results to your geo
dealer. He should be required to state that his design is suitable for
those water qualities. I knew I was taking a chance on the minerals but
deposition has been slow - a bit of mineral remover down the supply well
and flushed through should do it once I need to do it. The air entrainment
was not measured so came as a surprise. I don't know how to measure air
entrainment but it should be possible - might have to done on sight or with
special sample jars. No one - not my geo engineers nor any of the dealers
who quoted our place ever mentioned air locking.
Even if you get a quarantee on the water quality it probably won't do you
any good at all - mineral deposition takes more than a year and so can air
locking if the bubbles are small. If you get a PRV and there is any air in
your groundwater it may air lock in a few months like ours did. Where is
the over flow going to drain to? If it gets onto your neighbor's property
who gets sued? You or the dealer? Bet it's not him. He just says that he
has done thousands of installations so it isn't anything to do with his
work and thus must be something else. He won't know what but doesn't care.
He will have been gone for a year or more and just claims that you or
someone did something after he left - no way to prove anything was his
fault. Only the owner is left responsible because the water came out of his
well and why doesn't matter.
Another question - do you need a permit to discharge the return water back
into the well? I know some states don't permit it.
Another question - are you sure the 10% bleed water can be infiltrated into
the ground forever? Soils with high clay content have very low infiltration
rates. If that location over flows will it cause problems?
In our area there are many well drillers but only one is highly
recommended, one is OK and the rest are -----. I overheard one guy say
that, of the geo dealers, half are incompetent and three-quarters are
dishonest, or it may have been the other way around.
Around here geothermal has only recently gained popularity so it is a
business full of Johnny-come-latelys and get-rich-quick artists. Prices are
very much over-rated - knowing what I know now I could do our system better
and for at least half of the cost. I would never do open loop again.
If you do proceed as stated;
1. get the dealers to show you some sort of computations that the required
BTU's can be extracted from the single well concept with only 10% bleed
water - I am sceptical of the numbers. Will you run out of new incoming
BTU's in short order? It sounds too good to be true - why does one well
work fine when everyone else needs two wells or a single well with a
complicated design using a separator seal? You may spend a lot of money and
not gain much efficiency if you spend most of the winter on the auxiliary
system. There is no way to prove that you aren't getting the efficiencies
you hoped for and thus no way to recoup anything from the seller. I haven't
seen any references to a single well arrangement that did not separate the
groundwater from the injection water.
I did a crude estimate of the heat gained by the well. Of the 10 gpm 1.0
gpm would be bled off and thus 1.0 gpm is entering the well. The other 9
gpm is recirculating over and over again with mixing of the 1 gpm. A 1.0
gpm flow has about 5,000 BTU/hr for a 10 degree drop in temp (my heat pumps
drop the water temps by 8 degrees). A 350 ft long pipe might collect about
19,000 BTU/hr for a total heat gain of 24,000 BTU/hr by the well. Assuming
100% efficiency of the heat pumps that is all the heat you be gaing from
the ground around the well plus the 1.0 gpm inflow. Granted this is a very
crude estimate it is not out by 100%. If a 5 ton heat pump is extracting
60,000 BTU/hr then it won't be long before you are making ice cubes.
2. Heating or cooling capacity in tons is 12,000 BTU/hour so a 5 ton unit
shoud have about 60,000 BTU/hr. The Tranquility 27 5-ton Model 064 has only
60,000 to 66,000 BTU/hr capacity, for your pumping rate, from the manuals
I downloaded, for incoming water temps from 50 to 60 degrees. A lot less
than your stated 112,000 Btu's in your first post. The dealer who said you
needed two units to get 112,000 BTU's may have been closer to the mark. The
3 ton unit Model 038, capacity is 38,000 to 42,000 BTU's again for 50 to 60
degree incoming water temps. Both together would yield around 98,000 to
108,000 BTU's - could get to 112,000 with higher pumping rate or higher
incoming water temps. Is there some confusion of just what is intended? Is
one guy assuming the auxiliary would supply half the heat? How big is your
house and what is the insulation standard? It sounds like they are
recommending as much heat as for our house up here in a Canadian winter. On
the coldest nights (minus 36 degrees C and high winds) I set an alarm for
every half hour and checked if the auxiliary heat was on and never did find
it on (I tested that the indicator light was functioning properly). The
auxiliary is electric coils which see so little use that they have a fine
coating of dust so when I test them there is a distinct smell of burnt dust
in the house - no way the auxiliary is on without us noticing. I put R60 in
all ceilings, R20 all walls, extensive sealing of all gaps and all windows
are triple pane low E options. The geo sytem is very efficient - we have
over 5,000 sq ft on two floors plus a finished basement with an outdoor
wall for a walkout, 4 computers running all the time, a hot tub on the deck
heated and used all winter, plus every electrical toy we could think of and
in the past two very long and cold winters we paid from $300 to $350/month
for electricity; heating included. We have very low electricity rates in
our province - might be lowest in North America - around $0.065 kw/hr.
Did you actually see the heat requirement computations? I found dealers
wouldn't show them to me.
3. Will the state water well permit allow for the 10% bleed water and even
the re-injection of water? Find out before it's too late. Phone the state
well drilling authority. Most authorities won't allow bleed water wasting.
A family of 4 uses about 240 gallons of water a day but 1.0 gpm for around
20 hours run time is 1200 gallons a day - 5 times domestic use or put
another way, the waste of water for 5 houses. For sure you wouldn't be
permitted such wastage of potable water in the southwest states.
While you are talking to the state well drilling engineer ask him about
open loops, who has them, who does the best job of installing them, what to
look out for, will your proposed single well arrangement work, does he know
any customers of your dealers who have had their systems a few years, etc?
In my province the provincial guys are a great source of info - which I
learned too late.
4. You are on a potable water acquifer as indicated by the reference to
already having the well. That means you are subject to much more stringent
rules about potential acquifer pollution and this makes injection of water
less likely to be approved. If the dealer says to go ahead without a permit
get a better dealer. They'll catch up with you sooner or later and make you
stop injecting and then what? I was told by the provincial well guy that I
didn't need a permit only because our acquifer was non-potable and there
were no users of the acquifer. I was told that I would not have received a
permit for an injection well if the acquifer was potable water. That may
explain why there are few open loops around here - most other acquifers are
potable. Now that I think about it, I may have read somewhere that most
states ban injection of water into potable acquifers, some ban all
5. Well performance is critical. It would be a good idea to have the well
improved called 'well developement' by some. Your 35 foot drawdown for 10
gpm pump rate is on the high side - OK if it hasn't changed for a long time
but makes me wonder. My wells had 45 and 55 foot drawdowns for 16 gpm pump
rates which were considered way too high by my geo engineers. I acid
treated both wells and got the drawdown to 5 and 3 feet - acid makes a huge
difference in our limestone bedrock formations. Don't know your rock
characteristics but the state well drilling engineer would be consider the
best source for this info. Again a potable acquifer would have more
stringent regulations than a non-potable one. Maybe acid treatment would
not be allowed on a potable acquifer. You do flush it out very well after
the acid is finished doing its work but how do you guarantee that no acid
taste reaches the neighbor's well? Works best if you leave the acid in for
24 hours so there is a risk in some acquifers that acid could migrate and
not get flushed. Contact with the rock neutralizes the acid but it takes
time and much depends on how concentrated the acid is, what type and how
much you use. Local practice will dictate.
6. Your 10 gpm pump rate is way more than a domestic well would need so a
well that was fine for years will be subject to a much higher rate than
ever before for much longer periods of time and pumping much higher
volumes. Domestic use is around 60 gal/person/day so 4 people would use 240
gal/day. At 10 gpm the pump would run only 24 minutes a day. Geothermal
heating runs for much longer times than LP, gas or electric heat - the
supplied air temps are much cooler than from these other heat sources. So a
geo system runs most of the day and night in the winter - you could now
have the 10 gpm pump running 20 hours per day. That difference could lead
to problems that did not occur before like sand being drawn into the well
and plugging of well screens if they are used. Well development can help by
removing sand from the region near the well, if there are no screens. It
could also remove sand and sediment from the bottom of the well that were
left over from the original drilling but not removed if the well was not
developed at that time. If you are going to make the well a part of the
heating system you should make it as good a well as possible.
7. If your dealer does suggest a rubber seal to separate the well supply
and injection zones that won't be good enough. The 30 ft drawdown means
that the mounding up from the injection flow will be very high, in the same
range but lower. Thus the well won't have the capacity to accept the
injected water without either overflowing within minutes of turning on the
system if the injection is above the seal or just folding up the seal and
flowing past it if the injection is below the seal. Normally, supply is
below the seal and injection above but that could be switched. I wouldn't
want to pull up a pump on 450 ft of pipe with a rubber seal dragging along
- that is a heavy pull to be done by hand. The single well systems rely on
a good design which takes into account the location and capacity of the
fracture zones in the rock formations. The seal is located so that there is
enough capacity below the seal to accept the injection flows and enough
capacity above the seal to supply the required flows; or vice-versa. It
works best if the rock formations are tight enough that there is not much
vertical travel of water. Thus the supply water would not be cooled by the
injection water as in your proposal.
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