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Couple Questions - Hunt Stoddard - 07-30-2018
I'm working for a woman who has a professionally installed, off-grid PV system of moderate size. Outback inverter. She was told that she couldn't use a standard water pump from Home Depot. Instead she's running an RV pump off a 12V battery charged by a maintainer plugged into the inverter. (???) Does any of that make sense?
Second question: She would like to have a fridge with an ice-maker but doesn't have a UV purifier. She would like potable ice cubes. Is there a way to feed an ice-maker through a reverse osmosis filter, or another way to rig the ice-maker without using a UV purifier. She's concerned about cost and power consumption.
Thanks for any suggestions.
RE: Couple Questions - kalakoa - 07-30-2018
told that she couldn't use a standard water pump from Home Depot. Instead she's running an RV pump off a 12V battery
There are actually compelling reasons to use an RV water pump (with a DC-DC converter) instead of a big AC pump -- inrush on a 1HP motor is pretty brutal for a smaller Outback system.
Note that the little RV water pumps are also available for 120VAC, at which voltage they burn about 1A. Under $100 on Amazon.
Is there a way to feed an ice-maker through a reverse osmosis filter
I've been planning a separate potable water tank (with pump, separate plumbing) which could be filled with jugs from the spigot or a purifier system which can make "batches" of potable water (eg, don't leave it running 24x7, just a couple of hours here and there as needed).
RE: Couple Questions - Seeb - 07-30-2018
Bag ice in a chest freezer probably cheaper in long run. Also helps freezer coast longer
RE: Couple Questions - terracore - 07-30-2018
"Second question: She would like to have a fridge with an ice-maker but doesn't have a UV purifier. She would like potable ice cubes. Is there a way to feed an ice-maker through a reverse osmosis filter, or another way to rig the ice-maker without using a UV purifier. She's concerned about cost and power consumption."
There was a post on here previously about somebody who found a cheap pump that feeds the ice-maker from a standard $8.00 5 gallon walmart jug filled with free county water. Sorry I don't recall specifics, maybe it was a cheap RV style shureflow variety that only kicks on when the fridge is thirsty.
ETA: "She was told that she couldn't use a standard water pump from Home Depot. Instead she's running an RV pump off a 12V battery charged by a maintainer plugged into the inverter. (???) Does any of that make sense?:
I have a 4,000 watt (8,000 peak) MSW inverter that can't start our Grundfos pump. a 3,000 watt Generac generator can BARELY start it, and only if it's running in peak condition, warmed up, etc. Our 7,000 watt generator starts it without the pump complaining, but the generator sounds like a horse kicked it when the pump cycles.
So I'm not surprised by her setup.
ETA 2.0: My Samlex PSW inverter owner's manual recommends running an incandescent light off the inverter before starting a large inductive (like a water pump) load or else it will trigger protective circuits inside the inverter. Her Outback may not have this limitation, I only read about this strategy myself a few days ago. Reading about inductive versus resistant loads and how it affects inverters only made my head hurt, but combining the two in some cases can overcome the technological limitations of some inverters. Maybe this helps (running the light helps prevent the inverter from sensing a fake problem with lagging voltage):
"Inductive loads: Resist changes in current and as such, when you measure the current, it lags (is behind) the voltage. Electromagnetic fields are the key to inductive loads, and as such all motors (fans, pumps, etc), solenoids, and relays are inductive in nature. Inductance is measured in Henrys."
RE: Couple Questions - MarkP - 07-30-2018
For years I ran off an APC SmartUPS300. It was good for 2,700 watts 120vac, pure sine wave. It put out excellent quality power but was very sensitive. It had very little surge capacity. I never ran a domestic water pump off of it although I did run a small wastewater pump system of the kind that you would put under a bar sink in the basement to pump the drain water up to the regular sewer system. It worked fine. I actually had more than one of these UPSs and my friend is using one. He does start a regular water pump with his. It works OK.
I myself have a Dankoff 48vdc vane pump that works great. I had the smaller RV pumps before but they just did not have the output that the Dankoff pump does. I would not hesitate to run a 120vac pump off my current system but am nevertheless glad that I have the 48vdc pump. I do have a small 12vdc pump powered by a 48vdc to 12vdc converter to supply my RO water faucet. The RO water is produced from the larger pump and stored in a 55 gal drum from which it is pumped by the small 12vdc pump, which only runs when the RO watr faucet is turned on. There is a pressure switch built into that pump. It also has a bypass to allow variable flow without the pump constantly cycling.
RE: Couple Questions - Hunt Stoddard - 07-30-2018
I haven't yet looked at the specs of her Outback inverter, or even what it's rated at. However, I have been running all manner of power tools, compressors, even a fairly large Bosch hammer off of it without any hesitancy or trouble at all. These are pretty big inductive loads, which is why I'm a bit mystified by why the guy said a small 120 vac water pump wouldn't work.
RE: Couple Questions - Seeb - 07-30-2018
You can get a pump to meet the spec’s, try Grainger. The pumps at Home Depot are the cheapest crap.
RE: Couple Questions - MarkP - 07-31-2018
How does the ice maker know to turn the water off (how does it know that the ice tray is full)? You could just rig up to flow by gravity from a blue water cube. If the ice maker is smart, it will keep the water on long enough to get full. You won't be troubled by how long that takes because it happens automatically. If dumb, you will get tiny ice cubes since the low pressure will cause slow filling, but it should still work.
Obviously the higher the better but I bet you could put the water tote on top of the refrigerator and that would be high enough. A shelf outside up under the eaves would be higher and also safer in case of leaks.
I got 48vdc to 12vdc converters on Ebay for around $10 each. They seem to work OK. I used to have a 12 volt battery with battery charger. The battery alone was $100. The converter is a way better solution.
RE: Couple Questions - kalakoa - 07-31-2018
The converter is a way better solution.
Especially when located near the pump, so the long run is high-voltage.
That said ... the 110V version of the "little RV pump" is much simpler.
https://www.amazon.com/SHURflo-Industrial-Pump-Model-2088-594-154/dp/B0001FAA5Y/
(There are multiple listings for this product; I ended up with the one that charges $8 shipping.)
As for "not enough pressure", gang two together, it's still cheap, and the power draw is easily handled by anything but the smallest inverter...
RE: Couple Questions - Hunt Stoddard - 07-31-2018
quote:
Originally posted by MarkP
How does the ice maker know to turn the water off (how does it know that the ice tray is full)? You could just rig up to flow by gravity from a blue water cube. If the ice maker is smart, it will keep the water on long enough to get full. You won't be troubled by how long that takes because it happens automatically. If dumb, you will get tiny ice cubes since the low pressure will cause slow filling, but it should still work.
Obviously the higher the better but I bet you could put the water tote on top of the refrigerator and that would be high enough. A shelf outside up under the eaves would be higher and also safer in case of leaks.
I thought about something like this, but I'm not sure how well it will work. Some ice makers are very simple; they just keep churning out ice until you turn them off. How they know when to stop filling the tray with water I'm not sure. Others are probably computerized with all the bells and whistles. She hasn't actually bought the fridge yet. I would imaging with a scheme like this, simpler is better.