Posts: 2,654
Threads: 42
Joined: Sep 2006
I'll certainly defer to whatever MarkP said because half of it or better was over my head. I will pointlessly add that my older generator would set off the alarm on my computer UPS when I tried to use it and my newer smaller TroyBilt doesn't. Also, I didn't realize this was about a tankless system, which I guess explains the larger HP on the pump. I'm not familiar with tankless systems or the advantages of them other than obviously needing no tanks.
Pua`a
S. FL
Big Islander to be.
Pua`a
S. FL
Big Islander to be.
Posts: 7,734
Threads: 686
Joined: Jun 2011
Computer UPS systems spit out modified sine waves just like any other cheap inverter or generator and they are designed to power a box full of microchips. Is the microchip really the issue?
Posts: 14,116
Threads: 424
Joined: Aug 2012
I'll see your splitting hairs and raise you a technical term: "power factor". A pure sine power source (grid, conventional generator) has a power factor of about 1.0; modified-sine inverters may have a PF of as little as 0.55.
The "missing" power is most obvious with any kind of motor or heating element; these may draw slightly more amperage to compensate for the lower PF.
A "quality" switching power supply (the one in your computer) will not be affected much by the lower PF, but cheaper electronics (notably the ballast in a chinese compact-flourescent bulb) will operate less efficiently.
I use native DC for everything I possibly can, the simplicity and efficiency is worth the effort. One source:
http://12voltonly.com/
Posts: 1,839
Threads: 48
Joined: May 2007
quote:
Originally posted by Royall
Well, I got the tank, food grade liner, cover and cover support, pump, and filters in a package deal. This model Grundfos doesn't require an air bladder tank. So far I've been very happy with it.
Royall
Hale O Na Mea Pa`ani
Sure you are happy with it, until the power goes out. I was suggesting a back-up pump. Considering that you do not use a pressure tank in your system perhaps you could just get a 12 volt on-demand pump for power outages. Plumb it into your system as a by-pass and hook it into the 12v side of your generator when the power is out.
Royall, Do you have outages often, or for extended times?
Dan
Posts: 1,679
Threads: 203
Joined: Dec 2005
Dan, don't have that many "long" outages but they happen. Not so worried about drinking water(hell that's what beer is for) but makes it a bit easier to flush the toilet! The cost of tying in small pump, say 1/2hp with a 1gal pressure tank would probably do the trick. Be cheaper than getting another genset. Maybe find a used RV pump on eBay.
Royall
Hale O Na Mea Pa`ani
Posts: 1,839
Threads: 48
Joined: May 2007
Royall,
The propane store next to Pahoa hardware had the 12v demand (tankless)pumps for under $100. Will run for days off of a car battery or the 12v outlet on your generator.
Dan
Posts: 9
Threads: 1
Joined: Sep 2012
@Kalakoa I have to echo a bit of what you say here, that using as much DC powered devices, or utilizing the DC type currents can be allot less hassle due to most being 12v. Lower voltage = safer. Got to remember the main reason for using AC was to send the power over great distance. The voltage issues are in basic terms, the force at which the power is sent through the line(s). Its a bit complicated to run on/off grid with DC, but it can be done, and in time pays for itself really fast. Ever noticed that damn near "ever" small electronic device has a DC input?
Got off topic sorry, it might be better to get your system set up for a DC pump, they are cheap, as well as Energy Star rated Fridge's stoves, washers and dryers. Last thing, no one should down play the value of requiring a correct sine wave. One of the reason's they say you should use a "pure sine wave" is that the inductive load of the motor will have a greater harmonic distortion with the square type modified sine wave and be less effective and "louder". Oh and maybe the reason your pump wont run on your Honda is the inrush current is to high. That tends to pop those breakers quickly. Good luck, and DC power FTW [
]
Posts: 14,116
Threads: 424
Joined: Aug 2012
Amazon has small DC pumps for about $50, free shipping. Granted, 2.9gpm isn't much, but remember your showerhead has a 2.5gpm flow restrictor...
Posts: 46
Threads: 3
Joined: Nov 2011
Posts: 2,014
Threads: 46
Joined: Jun 2003
Reminds me I went thru 3 12vdc pumps before replacing with a 110 type. Brushes on one, never figured out the 2nd, just replaced temporarily with the third until I could upgrade. This was in a full time situation, not backup. Strangely, that last one is still being used by a friend (over 3 years)
David
Ninole Resident
Please visit vacation.ninolehawaii.com
Ninole Resident
