Author Topic: Dankoff Solar Force Piston Pump  (Read 26650 times)

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Revolutionary

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Dankoff Solar Force Piston Pump
« on: January 06, 2012, 10:23:27 PM »
I am going to buy a Dankoff Solar Force Piston Pump this spring, and was wondering if anybody owns one, and if they really ARE as sturdy as the sellers say they are. I'm going to pump about 200 feet vertically, probably 320 total, with no lift (feeding from the bottom of a 1,000 gallon cistern).
 Mine will also be running off of a 48VDC battery bank- solar panels feed the batts.
Thanks in advance-
Chris

rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #1 on: January 07, 2012, 12:25:59 AM »
I am going to buy a Dankoff Solar Force Piston Pump this spring, and was wondering if anybody owns one, and if they really ARE as sturdy as the sellers say they are. I'm going to pump about 200 feet vertically, probably 320 total, with no lift (feeding from the bottom of a 1,000 gallon cistern).
 Mine will also be running off of a 48VDC battery bank- solar panels feed the batts.

I have great misgivings about any of the DC pumps in this application. When I built here, I used a shurflo PD pump. Ran on 12 or 24V DC, was recommended by all the "professionals". And at $1300 it wanted to be a bloody good pump!

After only a few years, its pumping capacity had dropped a fair bit, but it still worked.
Another couple and it was stuffed. THEN I started finding out all the things I'd TRIED to find out before I purchased it.

The seals are prone to failure. WHEN (not if) they fail, the motor gets flooded. When that happens, the brushes, commutator and everything else gets ruined.
Spare parts are available - but holy hell!

Anyhow, long story short, I replaced mine with an inexpensive 240V AC bore pump off ebay. Figured it's italian, all stainless and bronze, fully sealed, no brushes etc. It takes 9-11 times as much power as the shurflo, but moves about 20 times as much water, so it's actually MORE efficient.

I'm pushing water 50 metres vertically and 150 metres horizontal from one 35,000 gallon tank at the bottom of the hill to another 35,000 gallon tank at the house.

I'm far, far happier with the new pump (after 2 years) than I ever was with the shurflo. And what I paid for the shurflo, I could buy 5 of these others and still have change.

wpowokal

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Re: Dankoff Solar Force Piston Pump
« Reply #2 on: January 07, 2012, 01:11:08 AM »
Not familiar with the pump I Goggled it http://www.pvsolarpumps.com/solarForcePiston.html it appears to be a standard positive displacement piston pump driven by a DC motor belt coupled, if you can not use an AC motor then it should work OK accepting that the Dc motor will need ongoing maintenance to brushes over time.

I suspect Ross had a close coupled pump.

Allan
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rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #3 on: January 07, 2012, 01:35:24 AM »
I suspect Ross had a close coupled pump.

Not "close coupled" in the way I think of it - where the pump is on the same shaft and can't be separated from the motor, but axially direct coupled, yes. The armature shaft has a flat on the end that mates with the pump. Why on earth didn't they do something like magnetic coupling, instead of using stupid seals that (from all reports) are well known for failing - and do so in stupidly short periods of time in terms of run-hours. (And the pump is such low volume, that it has to run lots of hours to achieve anything!)

The commutator and armature looked like this when I pulled it out:


There was simply nothing left of the brushes:


It was a model 9325. I'd never waste the cash on a DC submersible pump again.

By comparison, this gleaming beasty was 20% of the price and works far better. With no brushes to wear, and only one moving part as such (and no diaphrams, valves, pistons, plungers and "bits"), I expect it will run forever....

Revolutionary

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Re: Dankoff Solar Force Piston Pump
« Reply #4 on: January 07, 2012, 06:14:57 PM »
Ross, how much power does that AC pump draw? (& Thanks for the info..)
Chris

rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #5 on: January 07, 2012, 06:45:36 PM »
Ross, how much power does that AC pump draw? (& Thanks for the info..)
Chris

Comes in various ratings. There's one that I think is only 375W, one around 750W, one around 1.5kW.

I intended getting the 350/375W unit, but ended up getting the 750W. With a decent foot-valve at the pump, it doesn't start up under pressure so the starting surge isn't so bad.

It moves quite a lot of water: not withstanding the 150 foot static head, and pushing through a couple of hundred metres of pipe, here's how much water it's moving. (The entry port is 2" diameter but the pipe from the bottom tank is only 40mm)

wpowokal

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Re: Dankoff Solar Force Piston Pump
« Reply #6 on: January 07, 2012, 07:42:15 PM »
Ross that pump will not last forever especially if your water is aggressive, usually the motor fails before the wet end (pump) but provided you look on it a s a cheep pump then OK.

Allan
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rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #7 on: January 07, 2012, 07:59:56 PM »
Ross that pump will not last forever especially if your water is aggressive, usually the motor fails before the wet end (pump)

Allan, the water is super-soft, clean and no grit.
I was warned that most of this type of bore-pump usually burn the motor up, and that it's mostly because people don't take appropriate care of cooling. I thought simply dunking it in 35,000 gallons of cold water would do, but apparently not.

I made up a nice sleeve for it so that the water it pumps is forced past the motor body to keep it cool. I'm told by my friend who's a pump specialist of 40 odd years, that this should make it last well past "normal service life".


Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #8 on: January 17, 2012, 12:17:30 PM »
Rossw - Hey do they have those Italian pumps in 1hp?  I gotta lift 300' on a solar system to a 0 psi cistern.

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #9 on: January 17, 2012, 01:02:56 PM »
Chris,  IMO the Dankoff pumps are not so good.  Grundfos SQF is the real deal.  What GPM are you wanting to lift that 200 feet?

Ross, I agree with your friend about the sleeve, should really help.

Striider,  I just installed an 11 SQF lifting 10+ GPM 300 feet into a cistern, it uses 950 watts to do this.  It will run from AC or DC, so if you've no inverter it will be a good choice compared to an inverter and an AC pump.

Damian

rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #10 on: January 17, 2012, 08:10:51 PM »
Rossw - Hey do they have those Italian pumps in 1hp?  I gotta lift 300' on a solar system to a 0 psi cistern.

Sorry, I've given up posting on this forum since an admin with a chip on his shoulder deletes my posts as quickly as I enter them.
(I wonder how quickly this one is deleted)

JW

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Re: Dankoff Solar Force Piston Pump
« Reply #11 on: January 17, 2012, 08:26:56 PM »
Great,

Why dont you tell us about the Olsin Twins while your at it. If you start flaming again, your reply will be deleted...

JW

TimS

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Re: Dankoff Solar Force Piston Pump
« Reply #12 on: January 17, 2012, 08:29:56 PM »
Sorry you have a chip on your shoulder Ross.
I noticed that your previous comment in this thread was not deleted, so there must have been something in those other posts that was offensive in some way.  Hey dude, it wasn't me!  But if you don't have something constructive to say, then you probably shouldn't.  Know what I mean?  Sorry members for getting off topic here.   All the best.   ::)

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #13 on: January 17, 2012, 09:04:13 PM »
Damian - yeah I looked at those Grundfos, but that solution is substantially more expensive ($1800)  vs a 220 inverter ($470) and standard pump (Flotec FP3232 - $574.99).  My system is set up for 12 volt DC solar, so it would really be intriguing if the pump would run on 12 volts at all.  I do LOVE the idea of less points of failure though, although the 220 inverter offers options such as running other 220vac equipment at some point, too.  

I wonder how many GPM I would get running the Grundfos at 110v (since I already have a 1800 watt 110 true sine inverter).

Oh, can't find this in the tech documentation either:  Just in case, can a Grundfos run on modified sine wave?  My 110 inverter is true sine, but the 220v one I am looking at is modified sine.

Hmm, it just occurred to me that even on my present solar set up - 390 watts at 48 volts or so, I could cut the charge controller out of the loop, and to the pump directly on a sunny day and get water with no batteries or inverter required.  This flexibility could be a good thing.
« Last Edit: January 17, 2012, 09:28:52 PM by Striider »

rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #14 on: January 17, 2012, 09:34:04 PM »
Great,

Why dont you tell us about the Olsin Twins while your at it. If you start flaming again, your reply will be deleted...

JW

Well, funnily enough, both of them have made their peace with me and we're all getting on fine. How about that??

rossw

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Re: Dankoff Solar Force Piston Pump
« Reply #15 on: January 17, 2012, 09:35:28 PM »
Sorry you have a chip on your shoulder Ross.

Not really.

Quote
I noticed that your previous comment in this thread was not deleted

The exception that proves the rule perhaps.

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #16 on: January 18, 2012, 01:08:04 PM »
Striider- Bunch of factors here.  You can run the sqf on a modified sine wave inverter for short periods of time (I've done it) but Grundfos does not recommend it as a permanent set up.  There is no reason to do that though, if you have that 1800 watt 110 inverter, that will run it just fine up to about 10 gpm.  If you do that, you can pump up to that amount of water very safely with an sqf/110 inverter depending on how big the pump is.  That  is because with a battery/inverter system you can suck a lot more out of your batteries than the solar is putting in at any one time and the inverter capacity becomes the limiting factor, so for the 10 gpm, example, you could move 10 gpm at 300 feet head with 950 watts of 110 ac running through your 1800 watt inverter.  As you say, though, the better way to go is to go straight from the panels to the pump.  Is your solar array 390 watts at 48 volts (both nominal) on a fixed mount?  If so you will only produce that 390 watts at mid day.  That said, using a 6sqf-3 you can lift about 3.5 gpm 300 feet using 350watts at 48vdc and it will simply pump less if less power is available.  Now here is the important part, as I see it.  You can run that 220 v standard centrifugal submersible pump through the 220 inverter.  It will move about 3.8 gpm at 300 feet of lift and will use about 5 amps at 220 volts, or 1100 watts.  So the sqf is about 3 times as efficient overall.  These are approximate numbers and to fine tune them of course you could factor in inverter efficiency, etc.  One other thing that becomes important in these kinds of situations is to look carefully at the anticipated flow rates through your piping.  Just make sure that your line losses don't surprise you after it's all put together.  If you tell me more about your system I can look up the line losses. 


Damian

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #17 on: January 20, 2012, 11:16:07 AM »
Thanks Damian for all of the info!  Ok, so we are on the same page, I was thinking if I got the Grundfos I would not have to purchase a 220 inverter at all, at least now, so all clear there. 

I think I understand most of your math, and yes, the solar is on a fixed mount (a-frame roof).  We are not here all the time, so I put them up out of "zombie" reach.

As far as plumbing, I have no system yet- I am getting the well drilled soon, and will have to plumb it from there.   The well will be about 50 feet from the house, and the cistern will be a little closer.  The house is on casons about 2 feet off the ground, and the underside is accessible with removal of skirting.  

As the place is not a full time residence yet, I plan to run the pump and fille the cistern to maybe 100 gallons a weekend trip (depending on shower needs once I get a shower set up), and then leave minimal water in the cistern.  I was thnking also that I would run the Grundfos primarily on 110, since I would have to make a cutout to run it directly on the panels, and my batteries would get no charge during pumping.  If I am getting 3.5 gpm though, we are only talking about 30 minutes to get the 100 gallons I estimate I will need at a time.  Planning a 275 gallon cistern, but don't have it yet either.  Another benefit of the Grundfos is that it would run on my Honda EU1000 too, with no additional generator purchase necessary.  Hmmm, I am slowly talking myself into that extra 700 bucks!

I am also still researching how to get the water out of the cistern and up to pressure at the house with 12 volts.   At first I was planning an RV style Shurflo, but reading those don't hold up long so reading about other options.

Thanks again for the help.
« Last Edit: January 20, 2012, 11:20:24 AM by Striider »

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #18 on: January 20, 2012, 11:32:01 AM »
Drill the well and see what the static level, acceptable pumping rate and drawdown (if any) at that pumping rate are and go from there.

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #19 on: January 20, 2012, 05:56:12 PM »
Hey Striider,

I did not have time to flesh this out before, so here is the flesh.  Since your lift will be determined by the static level in the well, plus drawdown, if there is any, you will only really know your total lift once you have the well.  If you have other reasons to put in a cistern, such as the ability to haul water in, etc. then that may be a good way to go but the days of solar well pumps that can only lift water into a cistern and require a separate booster pump to supply house pressure are pretty much over.  I've done a couple of retrofits whereI replaced the cistern/booster setup with a straight sqf submersible/pressure tank/pressure switch set up.  The owners of those systems are not looking back.  It is true, as was mentioned earlier in this thread, that the early dc submersibles were a lot of trouble.  I too have seen the worn out brushes, destroyed armatures, etc.  In my opinion anyone who is still making a brushed dc submersible is living in the past.  I guess the little shurflo diaphragm pumps can be okay in very shallow wells where it is easy to pull them up and service them but I've never used one myself.  Also, about seals failing in the older models of dc submersibles; all submersible motors used to be sealed and run in oil.  Modern submersible motors, both ac and dc run in water.  They are still sealed, to keep out grit, but they use water to lubricate the bearings and if some water leaks in, oh well, plus no contamination of the well from oil leaking into it.  Anyway, my thought on what you are proposing would be that if you put in a small 48 vdc battery bank you could run an sqf to a pressure tank and turn it on and off with a pressure switch, giving yourself a nice house supply 24/7 without the need for a cistern.  As always there are lots of variables but I know a few people with this kind of system and they are very happy with them.

Regards,

Damian

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #20 on: January 23, 2012, 12:44:28 AM »
Damian - thanks again for the info.  Sorry for the delayed reply, as I was at the cabin with no internet on the computer this weekend.  

As far as waiting until the well is drilled, the reason I was trying to get all this info now was to pre-purchase the pump so I could have the well drilling guy help me put it down the well while he was onsite.  Come to think of it, I bet it is recommended to let the well "settle" after initial drilling to keep sediment and gunk out of the pump as much as possible?

The main reason I was thinking about a cistern system was to conserve energy by running a 12 volt pump to get the water pressure.  I REALLY like the idea of straight to a pressure tank instead, but have a couple of concerns.  

Temperature - It is quite frigid here in the Colorado mountains (-25 F a couple weeks ago), and I do not live at the property full time.  To use a pressure tank, I would think I would need to keep it's temperature above freezing, and this would require putting it underground.  With my frost line at 8 feet or so, I would have to make a substantial "vault" for it to provide access to it for maintenance.  This would be much more costly than burying a cistern.  I plan to drain the water system each time I leave, and each time I return I would be pumping water into the system again.  The temperatures inside my cabin usually stay up in the low teens or above just from ambient sun heat, but a long cold snap can cause it to freeze pretty hard in there, so putting the tank inside would help some, but not a bunch.  Some day I was planning to build a solar hot air heater system to keep the cabin more stable, but that is still "on the list".  

48 volt? - I am missing the logical jump on this part:  what would I need the 48 volt system for?  Can't I pump directly from the SQF to the pressure tank?  Right now, I am trying to stick to a 12 volt system.  The way I am envisioning setting this up, SQF would run primarily on the 110 volt system, with a (future) provision for cutting it over to direct panel power in an emergency (inverter failure).

If I can figure out a way to use a pressure tank without digging holes and burying anything but water lines, this would of course be optimal.  As far as hauling water, I have a gravity fed 55 gallon system in use now that could be un-mothballed should the need ever arise for this.

Oh one last question - reading about pressure tanks - it looks like you have to remove the bleeder orifice from the system.  This is a concern because I would need my water level to seep back down to 8 ft below the well head during the winter.  My pump would always be trying to overcome this small leak too.  Is there a way around this?

Thanks!  Eric
« Last Edit: January 23, 2012, 02:34:21 AM by Striider »

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #21 on: January 23, 2012, 06:12:25 AM »
Anyone know if there are any 110v options out there that can pump 300 ft into a pressure tank besides these Grundfos SQFlex?
« Last Edit: January 23, 2012, 06:21:39 AM by Striider »

Norm

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Re: Dankoff Solar Force Piston Pump
« Reply #22 on: January 23, 2012, 08:30:01 AM »
 
 
The commutator and armature looked like this when I pulled it out:


There was simply nothing left of the brushes:
 
It was a model 9325. I'd never waste the cash on a DC submersible pump again.

By comparison, this gleaming beasty was 20% of the price and works far better. With no brushes to wear, and only one moving part as such (and no diaphrams, valves, pistons, plungers and "bits"), I expect it will run forever....
 [/quote]
Gosh that looks like some car heater blower motors that I've gotten from the auto salvage yard
except the commutators were in a lot better shape......and like $2
Norm.

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #23 on: January 24, 2012, 06:53:20 PM »
Hi Eric,

Okay, I was kind of hoping that I would not be the only voice on this.  Anyway, the logical jump to 48 volts was because I remembered you saying your array was 48 volts.  In any case, (and someone who knows more than I about batteries may have some input as to whether this is a good idea or not), the SQF will not run on 12 vdc, it needs at least 36 vdc and 48 would be even better, so if in fact your array puts out 48 volts and you can run 4 12 volt batteries charging and running the well pump in series, but tapped in parallel to run your 12 vdc inverter, then that seems to me to be the best way to do this, in my mind just because that gets the inverter out of the well system and thus eliminates its losses and potential for failure, frees up the inverter for other tasks, etc.  I'm not as proficient in battery system design as I am in water system design.  Then again, switching 48 vdc may be a little harder to do than switching 110 ac.  I'd have to look that up.  Maybe someone here has some advice on that.  You may want to just run it from the inverter, it's easy, and that is a plus.  As far as the cistern vs. pressure tank question, you will have to bury a cistern and drain the lines to it etc. to achieve your frostproofing goals.  In my area frost depth can be four feet not eight feet, but the same principles apply.  Off the top of my head, if you want to frostproof the pressure tank system, you will bring a pitless adapter through the well casing at 8 feet below ground level and run, oh, at least about ten feet away from the well at that depth with your pump discharge line and put in a "stop and waste" valve.  This valve will have a sleeve running up above ground to insert a tool into to turn it on and off and when it is turned off, it will drain everything that is sloped towards it downstream of it and let that water perk down into the ground below it.  One caution about this arrangement.  Never run the pump with that valve closed!  From there you could run up to the surface and put your pressure tank there, drain it whenever you leave, and be in good shape.  How you drain the cabin I do not know but figure you must have thought of that, and you'll have to do it either way.  There are tons of variables in all of this, the well may run clear right away or it may need to be pumped with a kind of disposable centrifugal by the driller until it runs clear.  The depth from which you must pump the well water, more than any other factor, will determine your options.  Yes, you can, as I mentioned in an earlier post, run a regular submersible, and the smaller ones are available in 110 vac.  If you're not lifting the water very far the efficiency penalty and inverter sizing needed to run the pump and its starting surge may not be big problems, but the deeper you go the bigger those problem will be.  There are always six ways to skin the cat, and the best one is determined by way more information than I have about your situation, but you may also want to consider this, in my experience, the biggest complaint that people have with cistern/booster systems is actually the noise that the booster pump makes.

Hope any or all of this is useful,

Damian

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #24 on: February 01, 2012, 10:06:44 AM »
Thanks Damian.  I am going to wait until I know my depth before theorizing/planning further.  Leaning towards the Grunfos due to the one less point of failure at the inverter, and more power options.  I like the idea of the underground shutoff valve, but am still wondering about the vertical line coming up to the pressure tank and how to drain that, hmmm.

bergmanj

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Re: Dankoff Solar Force Piston Pump
« Reply #25 on: February 01, 2012, 01:46:28 PM »
Stiider,

I've been using a Grundfos 11SQ2 for about 5 years now.  Seems to be a good reliable pump so far.  The reason I went for it was that I could run it on 30 -- 90 VDC or standard AC.  I've only run it on 120VAC so far; but, wanted the options for battery use as am totally off-grid here with 2.5 KW solar, and a backup propane-fired generator.

At least we could get water with batteries-only.

Bought it from Panhandle Sales in Oklahoma.  They were priced about $1400.00 at that time - the least pricey of anyone.  Careful, though: I was told shipping about $15.00; they tried to charge me $50.00, which I called-them on.  My pump was direct shipped from Grundfos warehouse to me (absolutely no "handling" by them); and I checked the shipping with UPS after arrival.  Actual shipping at that time was about $12.50 for that specific shipment.  They reluctantly refunded my difference; and, told me they were taking me off their "preferred customer" list.

Beware of this type of issue when buying off the web.

Regards,   JLB

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #26 on: February 01, 2012, 08:39:48 PM »
Hi Eric,

The key to draining that vertical line is using a "stop and waste valve", a special valve that will drain the line "downstream", that is, the side of the valve that is toward the pressure tank, back underground when it is turned off (1/4 turn like a ball valve).  This type of valve  functions very much the same way a frost free hydrant functions, if you've seen those.  Anyway, hope it all works out for you.

JLB, way to go on the generator (propane), it never turns to varnish or biofouls.

Damian


bergmanj

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Re: Dankoff Solar Force Piston Pump
« Reply #27 on: February 02, 2012, 08:05:33 AM »
Damian,

Homestead is as much propane as possible (no gas refrig, though) for efficdiency reasons  -  using fuel at the heat need is by far more fuel-efficient than any electric, including utility: Utility is relatively "cheap" only because they are able to buy coal at ~$22.00 / ton right from the mine; the generating process is typically only about 33% efficient (~7 -- 14% by the time it gets to the wall outlet).

Went with "spark-ignited" generator prime-mover to enable me to use woodgas in the event of severe propane (and other fuel) shortages.  Would really like to fuel that way all the time, but woodgas can be really bad on an engine if not properly cleaned and neutralized.

Grundfos pump works really good, so far.

Regards,   JLB

thirteen

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Re: Dankoff Solar Force Piston Pump
« Reply #28 on: February 03, 2012, 02:33:09 AM »
I have a Shurflo that has been running off and on for 7 years 12V. It pumps while we are up there when we use the water. It sits during the winter months but it has worked whhen ever we needed water. I pump right from the creek. 7 ft up and 30 ft to the system in the house. Probably 65 hrs a year. Never a probleme. Hopefully I will be up there full time this May or June. It will be tested good by the end of November. I will have a gravity flow system for my water and the plans are to use it for a boost pump for thhe on -demand water heater.  I will be using Berkey Water filter fo rmy domestic drinking water.
MntMnROY 13

damian

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Re: Dankoff Solar Force Piston Pump
« Reply #29 on: February 03, 2012, 06:37:43 PM »
Hi Thirteen,

Yes, I've seen those shurflos work well in the type of low head situations you are describing or as pressure boosters.

Damian

Striider

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Re: Dankoff Solar Force Piston Pump
« Reply #30 on: February 06, 2012, 03:33:31 AM »
Thanks again for all the help so far guys.  I will get back to you when I have the well drilled.  Should be receiving my permit back any day now...then I can schedule the drill.  Perhaps I will start my own topic, as I seem to have hijacked this one a little bit :)

thirteen

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Re: Dankoff Solar Force Piston Pump
« Reply #31 on: February 06, 2012, 04:09:15 AM »
Damian
This is used as a pump directly from the creek right now. But when my domestic water tank is in it will be around 40 foot above the house but it has to cross the creek, the road, and the lawn about 60 ft of horizontel line then up about 3 ft all gravity fed. This is where my pump will be located. It will be used for the on-demand water heater only. It requires a certain amount of flow/preasure to run properly.  Everything else will be gravity feed. My garden will be watered direct from the creek with gravityflow line stuck in the creek bed. I happen to be lucky and have several springs on my property.
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SteveCH

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Re: Dankoff Solar Force Piston Pump
« Reply #32 on: February 06, 2012, 11:46:15 AM »
Striider, what you are thinking about is what we've been living with for many yr. Except that our cistern is about level with the house and not for gravity feed. By the way, this is in Colorado at 8500 ft. We live here full time, so the problem of leaving the house to possibly freeze [and with it the water lines inside] isn't a factor.

Our cistern is above ground, built from cinder block on a concrete pad. I insulated the walls with 4" foam panels, then those are faced with stone for looks and UV protection and etc. The top is also insulated. However, even so, there have been a few winters during which we had the supply line to the house freeze for a few days. I tried heat tape and insulation for the ten ft. run and it would still freeze up. If you bury a cistern and have underground lines below frost level, you would likely be ok except for the very unusual deep freeze you might get once a decade or so.

The cistern itself has never frozen. 2200 gallon volume.

We pump water uphill from our well, which is 100 ft. lower elevation than the cistern. The line from the well is only a few inches deep in the ground, as the ground is mostly rock and the topsoil, such as it is, is only a few inches deep. So, I must drain that line completely after adding water to the cistern. I have a set of valve down at the well head with a drain line tee'd into the supply line to do this, plus a curb-stop valve or whatever they are called about 8 feet down set into a bed of gravel to drain the last few feet of that line.

We have the Grunfos SQF running off our 120 volt house inverter. I turn the pump on manually when we want to add water to the cistern. Which I only do during sunny spells, since our electrical source is PV.

For the house pressure, we pump water from the cistern up about 4 ft or so elevation into the house and the pressure tank. We use a Dankoff Flowlight pump for this, 12 v., and it is automatic via a pressure switch.

In your case, as no doubt you realize, no matter what system you install, you must plumb it so that you can drain everything, including the pressure tank. Since sometimes your building might freeze.... Of course, your pressure pump, if you decide to go that route, must also be drained.
« Last Edit: February 06, 2012, 11:49:05 AM by SteveCH »