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glock20
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# Posted: 8 Apr 2012 17:16
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Hi folks,
I'm currently building a cabin and are struggling with water heater options. I'm off grid and was initially leaning towards one of the Bosch on demand units that require no power. My research has taught me that on demand units are fussy about consistant water preasure and flow. I'll be pumping from a water tank so I don't know if this is a problem or not. Another option is a manufactured home water heater because it uses outside combustion air which is required for propane. Any suggestions would be greatly appreciated.
Thanks
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optimistic
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# Posted: 8 Apr 2012 18:02
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Hi glock20,
I do not know if you own a generator but if you do, and it's rated at over 2000w (better if it's closer to 3000w), then you can use this kind of water heater:
http://www.homedepot.com/Plumbing-Water-Heaters-Point-Of-Use/h_d1/N-5yc1vZbqo7/R-1001 37155/h_d2/ProductDisplay?catalogId=10053&langId=-1&storeId=10051
It is 20gal but they also carry 10gal. An average short shower, with low pressure shower head, will use around 5 gal. So if, for example, you and the wife want to take a shower over the weekend when you are in the cabin then you can do with the 10gal. I would opt for the 20gal so when you have guests you will have plenty of water for 4 ppl to shower. It takes between 30-40min to heat up so it isn't a big deal to start the generator for it, heat the water, turn off the generator, and that's it...
Also, I'm not 100% sure about this, but while you run your generator you might be able to run off the excess electricity from the generator to the batteries of your off grid system to be really efficient... I might be wrong though.
good luck!
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rayyy
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# Posted: 9 Apr 2012 17:04
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I'll tell you what,I love my Eccotemp L-5 .It's just a cheap little on demand hot water heater.You have to supply it with propane and pumped water.I have mine hooked up to a 12 volt DC rv pump and it does fine.You are only burning gas when you use it.No need to keep 20 gallons of water hot all the time 24 hours a day..And it really is nice hot water to use in just a second.To me that is so much more efficient than a standard hot water tank.
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razmichael
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# Posted: 9 Apr 2012 18:08
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Agree with Rayyy - I have a 12v RV pump providing pressure to both a cold and hot faucet. The hot runs through the L-5. The pump comes on automatically when either faucet is turned a bit due to a built in micro switch. You can also use the pressure switch in the pump with or without a pressure tank but I selected the switch (reasons discussed in a previous thread). Batteries in the L-5 last a long time (only needed to ignite the propane) but hooked mine into the 12 volt system (reduced to 6 volts).
I have also used a Zodi for many years - not nearly as automatic as the L-5 but small, portable and effective. Th L-5 is suited to use in a more semi-permanent installation (just avoid freezing.
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kenacp
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# Posted: 9 Apr 2012 19:00
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I have the 20gal water heater from Home Depot and IMO it takes too long to heat up. I am thinking the Eccotemp L-5 (or the next one up) might be the better option for off grid. Pretty cheap on e-bay.
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optimistic
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# Posted: 9 Apr 2012 20:16
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Kenacp - how long does it take to heat up?
In regard to this comment: "No need to keep 20 gallons of water hot all the time 24 hours a day"
In case I wasn't clear, you won't keep it on 24hr but only turn it on when you need to take a shower and turn off when you have enough hot water to shower. If you want to make you life easier you can buy those 5 dollar timers that so ti will turn on and off by itself at certain hours or even use those timers that you click and then it runs for a set time which will allow you to click and forget when you want to take a shower.
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rayyy
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# Posted: 10 Apr 2012 06:17
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No-no optimistic,the heater automaticaly shuts off when you turn the faucet off.There is no storeing hot water involved.The second you turn the hot water faucet on,the heater detects the water flowing threw the line and autmatically ignites the burner which heats the water up right then and there.It's warm at the shower head befor you get there.When you are done showering and turn the faucet off the heater detects no more water flow and shuts off the burner automatically.The flame igniter is powered by D-batteries in the heater.You can also ajust the tempiture and the pressure of the water by 2 knobs right on the front of the heater.Once again,your not heating water up in a tank.
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optimistic
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# Posted: 10 Apr 2012 12:53
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Rayyy.... You have completely misunderstood me. Not sure why. Perhaps a closer reading on your part will suffice?
You are confusing two types of systems - on demand and tank heaters and you are commenting as if I am the one who mixes them.
When you wrote that there is "No need to keep 20 gallons of water hot all the time 24 hours a day".
Obviously, you were referring to a tank heater.
I then responded to this in my second post: "you won't keep it on 24hr but only turn it on when you need to take a shower and turn off when you have enough hot water to shower." Again, referring to a TANK HEATER.
You then replied as if I made this comment in regard to an ON DEMAND system stating that "the heater automaticaly shuts off when you turn the faucet off.There is no storeing hot water involved."
You are talking about an on demand while I, and kenacp for that matter, are talking about a tank heater.
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rayyy
Member
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# Posted: 10 Apr 2012 16:31
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Sorry,Your right optimistic,I understand what you mean.
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optimistic
Member
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# Posted: 10 Apr 2012 17:13
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No problem brother. I hope I didn't come off as an ass... 
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yankeesouth
Member
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# Posted: 10 Apr 2012 20:24
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rayyy and raz.....
I have a question about the zodi and eccotemp. I read some reviews and if I recall I thought I remember reading they will only heat say 45 degree water up to around 65-70 degrees at the shower head. Do you find that to be the case??? I was thinking about getting of those systems as well but decided on a tank because I was afraid the water wouldn't get hot enough. In the winter there is a possibility of pumping 35-38 degree water into the system. How cold is the water you pump into your system and how warm does it actually get? Wife and kids like it hotter than just warm. I am not saying it has to be steaming hot but will really cold water come out fairly hot not just warm? Does that make sense?
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razmichael
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# Posted: 11 Apr 2012 07:11
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I suspect those figures are fairly close for the Zodi (single tank system). I love my Zodi but it is not a real on-demand system. You need to start the pump then start the propane (and adjust the gas). When finished you need to turn off the propane before turning off the pump. I rarely use it directly but (as the mnanual suggests for cold water) recycle the water in the container until it becomes as hot as I want, then turn off the propane and just use the pump. The zodi is perfect for what it is designed for - portable, simple, robust. It is not idiot proof and not designed for use where people want to turn a tap and get hot water.
The eccotemp L5 is a true on-demand system and, depending on how you install it, can provide hot water simply by turning on a tap. The L5 is the smallest portable type system. The documentation on the website for the L5 states 'The L5 will offer a 35 to 40 degree rise at 1.3 gallons per minute'. I think you can also reduce the flow thus increase the temperature rise. My source water is not overly cold so I have not had any issues with temperature. If your source water is very cold you may need to look at the L10 or another larger system. Given that on-demand systems are installed in residential houses, it all depends on how much you want to spend, power availability etc. I suppose you could also plumb a pre-heat tank system but at a certain point it becomes more complicated than value added.
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rayyy
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# Posted: 11 Apr 2012 17:56
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My water sorce is never cold either.The stats say the eccotemp L-5 heats water up to 80 degrees to 120 degrees.Maybe that 80 degree low end is based on 36 or 40 degree water flowing into it.It's true too,you can slow up the flow so the water is passing through the heater more slowly allowing it time to pick up more heat.What's so amazing to me is that it is just so quick.That water is hot in just a couple of seconds.
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glock20
Member
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# Posted: 11 Apr 2012 20:46
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Thanks everyone....great comebacks. I appreciate the help.
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MO Cabin
Member
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# Posted: 17 Apr 2012 22:03
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Would it be possible to change the shower head in an eco temp to a low flow option like this one http://www.showerheadstore.com/lowpressure.html and just have a gravity feed system?
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MtnDon
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# Posted: 17 Apr 2012 22:24 - Edited by: MtnDon
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Could work. One thing to know is that all the shower heads that have mechanisms that introduce air into the water flow feel cooler than a water stream without the air injection. That may mean needing to run more hot water than otherwise in order to feel comfortable.
FYI, 0.43 psi per one foot of water head.
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razmichael
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# Posted: 18 Apr 2012 07:18
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The eccotemp L5 and L10 need a good 20 PSI to work so gravity fed would need a head of over 46 feet minimum? The shower head will not have much influence on this - just makes better use of limited pressure for a shower (and colder as MtnDon states).
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rayyy
Member
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# Posted: 21 Apr 2012 11:01
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razmichael is right,you do need continuous water pressure for the heater to work right.You can buy a sureflo 12 volt RV pump from J.C.Whitney reasonably priced but youll need a 12 volt power supply.It is self primming and has a built in pressure shut off switch.Messing with to low of water pressure can be dangerous.That water get's mighty hot.I found that out when I ran my tank dry and the water passing through the heater got some air slugs in it which shot the temp up to spirting steam out with slugs of scalding hot water.
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