propane water heater

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blueskies
blueskies Registered Users Posts: 54 ✭✭
in Solar Beginners Corner #1
Hi all,
I have a well insulated "cabin" / cargo trailer with solar panels on the roof and everywhere else I can put them.   Although they have proven to take care of all electrical needs - including a window air conditioner - i have determined I will have to rely on propane for hot water.  I suppose I can cut holes for ventilation of a propane water heater.  I only need to take a shower every day and maybe shave.  I have a kitchen sink and hot water would be nice for that too but cold water and soap might be o.k..  I am looking for recommendations for an efficient and reliable water heater.  Unfortunately, I have determined that using my solar set up for hot water is not currently possible.  All suggestions are welcome and thank you for all your advise.
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #2
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    A propane water heater as used in RV/trailers would be my recommendation.  It would be mounted to a wall (inside) with no stack venting needed.  Go have a look at an RV place or on line.  They are available in propane/electric too.   It could be a bit of a dump load when you have enough solar available.  

    Only 5-6 gallons, but that suffices in my trailer, you never run out of hot water, and can switch on or off as needed.  10 minutes warms it up completely, so I never leave it on constantly.  Good for small capacity/size restrictions and small useage.  I have a Takagi instant water heater for home use, but that's waay more than it sounds like you need.
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  • NANOcontrol
    NANOcontrol Registered Users Posts: 262 ✭✭✭
    #3
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    It depends how you define "possible".  I used to heat with propane, waiting around for it to heat up, the expense and never ready when you want it. It is nice waking up in the morning and having hot water at the sink. .   Now I heat with PV solar and sold my propane heater.  You can't begin to realize how much excess power your solar system wastes each day.  If you have all the panels that will fill your roof, there is more than enough.  These nice little point of use 6 gallon water heaters are nice.  They only take a KWH of energy a day to get them up to get a full 60F increase.  Any reasonable system has that much extra.  I have a 6 and a 9 in series for the house (I run a dishwasher) and a 40 gallon in the garage just for the washer. I divert excess right from the panels into the 120V element be it as low as 5W or 500W. Those little bits add up all day.I didn't have to add extra panels.

    Here is where "possible" comes in. This.isn't pre packaged and I don't see why not. It is quite cheap to do and it is amazing how well it works.  It is an uphill struggle to educate the solar world to this and untill then the demand for these products won't be there.

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  • blueskies
    blueskies Registered Users Posts: 54 ✭✭
    #4
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    i am sure you are correct and plan to move that way.  in the mean time i plan to use this:
    https://www.youtube.com/watch?v=srqpldS_H_0
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  • littleharbor2
    littleharbor2 Solar Expert Posts: 2,048 ✭✭✭✭✭
    edited August 2020 #5
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    I have had very good luck with the inexpensive propane tankless water heaters. Some creative plumbing will allow you to mount the tankless outside the RV and remove when needed. This one pictured is like the first one I bought and still works to this day 15 years later. I have two larger ones now in Baja which, again, work great.

    2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old  but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric,  460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.

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  • wellbuilt
    wellbuilt Solar Expert Posts: 763 ✭✭✭✭
    #6
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    I use a tankless like above , it’s screwed on the wall in the bath room and makes hot water . 
     120$ a few years ago . 
     We had a small pump sucking water from a 5 gallon bucket  when you run out of water your shower is over , I had some soapy little girls running around for a few weeks befor they learned 
    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
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  • InCogKneeToe
    InCogKneeToe Registered Users Posts: 73 ✭✭
    #7
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    Yep, Tankless here too. Instant On, slick as snot.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,461 admin
    #8
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    If you use (and have) an RV tanked water heater, turn on (pilot/burner on) to heat the ~5 gallons of water, and turn it off again--Then you are not going to save much propane vs a tankless heater (tankless save lots of energy by not "keeping" the water hot 23 hours per day, just to use hot water for 1 hour).

    So, if you have an RV hot water tank and it works well--Probably just keep it. If you don't a tankless may be good for you (there are min/max water flow rates--You need to make sure your water system can meet the minimum flow rate to activate the tankless heater burner).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Ralph Day
    Ralph Day Solar Expert Posts: 1,019 ✭✭✭✭
    #9
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    The modern rv water heaters (and fridges, stoves and furnaces) have pizo-electric ignition sources instead of pilots nowadays.  Much preferred to lighting pilots that have a tendancy to warm your living space and/or blow out at inconvenient times.
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  • Graham Parkinson
    Graham Parkinson Registered Users Posts: 160 ✭✭✭
    #10
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    Don't know if they make one in an RV size, but the Bosch flash heaters with no pilot light are great (water turbine powered ignition: turn on a tap, turbine spins up, generates power to spark ignition) - no holding down button, snapping on piezo starter, counting until safety warms up ...  However they do require about 30 psi to operate.

    Offgrid in cloudy PNW

    MacGyver'ed museum collection of panels, castoff batteries and generators - ready for state of art system install .... parade of surviving and dead generators: H650, Ryobi 900, Briggs and Scrap Iron 2000, H2200, H3000, Kubota 3500, Kubota 4500, Onan 7500

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