question about replacing 110 V pump with 12V pump (Long )

[strider3700]

  I live on grid but far enough from town that I experience power outages semi regularly in winter  and they are down long enough that it becomes an issue.  I was entirely dependant on electric for heat and to keep my water flowing so after one very very cold day last winter where I couldn't flush the toilet I've decided to make some changes.

The heat is simple.  I like wood stoves, that project is underway and should be fine.

The water on the other hand is something I've been thinking about a lot.

My system currently is  the following

A spring collecting in a surface pond

Gravity feed into my "shop" where it goes into a 200 gallon tank

the 200 gallon tank has what looks like a toilet ball valve floating in it to prevent overfilling.  I get good pressure at that valve.

It also  has ozone bubbled into it to kill things.

coming out of the bottom is a T that connects the 200 gallon tank to both the line into the filters and into a 3000 gallon tank outside.  I believe that the water in this outside tank isn't really moving much because of the T.

There is a 1 HP hottub pump running on high 24/7 to keep the water circulating in the 200 gallon tank and I'm assuming it's hoped that the outside tank will circulate as well.  It costs me about$30/month in electricity.

After the T you  get a charcoal filter and then a water softener that I've turned off, and then into a pressure tank with a on demand pump to keep it at house hold pressure.

So now that you know what I have  here are my plans on changes.

I'm going to move the 3000 gallon tank to be up a bit on the hill.   Water will come from the spring to it and it will have a similar valve as the 200 gallon tank.  from the 3000 gallon it will gravity feed to the 200 gallon.

I will replace the 1hp hottub pump with a small 12V circulation pump. Something that moves 3-5 gallons/minute and it will just circulate the 200 gallon tank.  

Here's the part that I'm unsure of,  I want to run the 12V pump off of grid power 99% of the time but be able to move to battery during outages.   The little 12V circulation pumps can be run off of solar panels of less then 50 watts in many cases so I was thinking of wiring it to an old computer powersupply.  They are 300 Watts and have a 12V output.  Then I can run from the wall via that supply.   When power goes out I will go out and change the connection over to 12V from a battery.

If this works then I'll change the on demand pressure pump to be a 12V as well and do the same thing and increase the battery bank at that time.    

My hopes is this will give me some form of backup for limited periods  and will greatly reduce my electric bill.  This winters project/hobby is going to be trying my hand at a windmill,   If it's effective I'll set it up to charge the batteries.  In the mean time I'll just put a battery charger on them monthly to keep them topped up.

Sorry for a long first post,  just trying to provide details.

Any Thoughts?

Jamie

[drdongle]

Your change to feeding the 3K tank then the 200 is exactly what I would do. I'd also eliminate the large pump for circulation, that was definitely overkill. You could use a dual pump system ( one 120 VAC, a second 12 VDC)or you could simply punt the circulation pump during power outages as long as the temp in the shop is high enough to prevent freezing.

Be aware that computer power supplies need to have the +5 volt supply loaded to work properly ( that is the red/ black wires), a 5 Ohm, 10 or 15 watt resistor would do that.

[strider3700]

Thanks for the info,  I didn't know about the power supply needing a load on the 5V to run.

Does anyone have suggestions on 12V pumps appropriate for the circulation pump?  I'll take recommended brands as well,   There are tons of these things out there but I'm not sure which to go with.

[drdongle]

Seems to me that a 12VDC Recreational Vehical water pump would do the job, they run about $70 US, Northern Tool, and Granger have them. You can also get them with a built in switch that turns on the pump when you open a valve. I'm not sure what kind of lift power they have, it might not work if you have a 2 story house.

[ghurd]

Have you looked at Dankoff pumps?

G-

[nothing to lose]

Have you thought about just changing the motor on your existing pump?

I've ran acrossed several that the pump is just a bolt on attachment to a motor shaft, if yours is it may be easy to just swap motors. Use any AC or DC motor you find laying around that will work.

If your going to change to small pumps, have you thought about running off a UPS backup? I mean if you have to charge batteries from the grid anyways. Get one rated high enough to power the pumps, 110Vac. When power fails you shouldn't have to switch anything, power comes back on batteries recharge. Add more large batteries as needed.

I have ran a UPS off 24Vdc, 2 115amp hr 12V deep cycles just fine. I think that one was rated 800watts, forgot for sure though.

I am thinking if you do this and are primarily grid powered it may be better than batteries and constant charging. Latter when you get the wind gennies runnning then pull the wall plug for the UPS and run from batteries only and charge those from the windmill. If you use Ups larger than the small pumps require then you could also have lights etc.. on the same backup system.

12Vdc pump would probably be best if you had 12Vdc power source, but if yours is the grid 99% of the time then I think a UPS and 110V pumps would have less loss perhaps than charging batteries all the time. Lots of cheap low volume 110V pumps available. Maybe a cheap pump for those decorator ponds would work good for circulating water.

[strider3700]

The pump/motor on the current pump appear to be almost impossible to seperate,  it's all in one outside case anyways.

I'd much prefer a 12V system to a 110V system.  I stand a chance at generating my own 12V  but 110 is more difficult.  I'm trying to be as self sufficient as possible,   it's just a quirk in my nature that worst comes to worst I'm able to do as much as possible myself.

[Experimental]

   Hello Jamie,

     What you want to do, is actually, very simple..

    I have a remote cabin, with no power, except what I create, and for several years, have been running off a 65 watt solar panel and batteries !!

    I recently added a wind generator -- but, back to your water supply !!

    Above my cabin, I have a 1350 gallon water tank, that gives me about 2 PSI water flow by gravity alone -- but I have a 12 volt Shurflo pump that supplys 2.8 gallons a minute and shuts off, automatically at 45 PSI -- comes on again, when a valve is opened and draws a max, of 7 amps --

     This has been quite addaquate, but when takeing a shower, pressure drops a little, if another valve is opened, but not much !!

     I would not recommend using this pump for your circulator, as I don,t think it is a constant duty type -- But, I wonder if you need a circulator, constantly !!??

     I would think you would only need to circulate water, once or twice a day, and would put that on a timer -- even if this is a part of a purification unit !!

     My tank, sits, often for several weeks or months, and I have had no problem with water purity -- as i filter it before it goes into the tank, and again as it comes out ..

     In a home, where it is used constantly, i wouldn,t think that circulator was necessary-- unless, this is a cistern, and not filled from a well !!

     At any rate, as Ghurd pointed out -- look in the Granger and Northern tool catalogs -- or just drop by a RV supply store -- but, compare prices, and another thought, is Ebay -- As I bought one pump thru them !!

     Let us know how it goes, Bill H......

   

[Flying Z]

Wal-Mart has 12v bilge pumps for about $20. Like previous poster said, put on a timer, maybe on 30 off 60 or something like that. I am thinking about getting one for my hydroponics system. I really like the idea of the UPS, hadn't thought of that.

[ghurd]

The cut-off head on them is about 9 feet, and drops fast as the battery gets lower.

The brushes will wear out about every 3 months with 24/7 use.

But it would make a fine 12V backup circulator when the grid is down less than 1% of the time.

The Attwood V625 uses about 1 amp with a very low max head, great for a low pressure backup circulator.  They move a LOT of water with only 1A in the right situation.

G-

[strider3700]

Just thought I'd throw in an update.  I tracked down a little 110 V constant duty pond pump from a local hydroponics place.  It flows 500gph and only draws 43 watts.

  I had to do some plumbing work to get it to swap out the old monster. Anyways the tank is no longer hottub like.  It's still got a good swirl and the ozone is bubbling away in there.  

The only real thing I notice is my shop now smells very very strongly of ozone.  I'm assuming that the old pump either forced the ozone into the water some how  or else the swirling trapped it in.   The vent into the roof definitely isn't drawing enough of the smell out anyways and I need to actively vent the room to stop from keeling over in there.  A new shop is underconstruction and I will be setting up active venting in there to help fix this issue.   I'm also going to be getting my water tested later this week to verify that it is still safe and my changes haven't affected water quality