tankless water heater off gird

solarhillssolarhills Registered Users Posts: 7
I need a new tankless heater and was wondering if anyone had experience with AC powered units. I'm concerned with waking up my inverter which is generally in sleep mode. I was considering a Bosch non-electric but wouild like to use a heater that uses direct vent. I would appreciate any help.

Charles

Comments

  • mike95490mike95490 Solar Expert Posts: 8,169 ✭✭✭✭✭
    Re: tankless water heater off gird

    So are you asking about AC powered heaters, or direct vent Gas ?

    Do the gas units require AC to light up ? An inverter in sleep mode, will only intermittently "ping" the AC loads to see if something wants full power. Your gas ignition system will need to draw AC above the detection set-point, to trigger the inverter.

    What if the inverter thinks the load has gone away, will the gas still flow, or does it shut off with power failure ?

    not any answers, but questions to figure out what you are asking
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  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    I have used the Takagi TK Jr with great success ON GRID. I know that if the power is off and the water flows, the gas WON'T FLOW. As for running it on an inverter and getting it to wake up, I would guess there would be no problem, but you might contact Takagi, or Bosch or Rinnai or Paloma tech support with your question.

    I still use the Paloma Legacy series off grid. These units are being phased out because they have standing pilots and are a bit less efficient, but they are bullet proof. If you turn the pilot off they are quite efficient.

    Tony
  • MangasMangas Solar Expert Posts: 547 ✭✭✭✭
    Re: tankless water heater off gird

    In the old ranch house off grid, I had an Aquastar propane unit with standing pilot which worked very well.
    Ranch Off Grid System & Custom Home: 2 x pair stacked Schneider XW 5548+ Plus inverters (4), 2 x Schneider MPPT 80-600 Charge Controllers, 2 Xanbus AGS Generator Start and Air Extraction System Controllers, 64 Trojan L16 REB 6v 375 AH Flooded Cel Batteries w/Water Miser Caps, 44 x 185 Sharp Solar Panels, Cummins Onan RS20 KW Propane Water Cooled Genset, ICF House Construction, all appliances, Central A/C, 2 x High Efficiency Variable Speed three ton Central A/C 220v compressors, 2 x Propane furnaces, 2 x Variable Speed Air Handlers, 2 x HD WiFi HVAC Zoned System Controllers
  • westbranchwestbranch Solar Expert Posts: 5,127 ✭✭✭✭
    Re: tankless water heater off gird

    I don't know the brand (none to be seen) but my (pilot light-less) camper HW heater (5 gal) controller that runs off DC, so there must be a supplier out there somewhere. perhaps check with an RV vendor/repair place...

    HTH
    Eric
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
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    West Chilcotin, BC, Canada
  • nigtomdawnigtomdaw Solar Expert Posts: 705 ✭✭
    Re: tankless water heater off gird

    Most of the standalone tankerless water heaters in Europe are Dc (battery powered) Piezo ignition systems. Even the new Solar Compatable Bosch (Junkers in Spain) units are battery piezo ignition .
  • Chuck46Chuck46 Solar Expert Posts: 95
    Re: tankless water heater off gird

    Ive used a Bosch for 2 years now. No piolt has pizeo ignition and works well for my self and my wife.

    Chuck
  • solarhillssolarhills Registered Users Posts: 7
    Re: tankless water heater off gird

    Thanks for the input all. A point of claification. I'm thinking of getting one or the power direct vent units to avoid a large vertical vent , get the advantage of outdside air intake, and obtain a larger capacity unit. I'm aware of the micro turbine Bosch that needs no power, but it doesn't direct vent and is small in capacity.

    Thanks again,

    Charles
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    Charles,

    As I said, I think the Takagi TkJr, direct vent SHOULD work with with an inverter in sleep mode, check with Tech support. A simple alternative would be to wire a 120vac light next to the point of use, turn the light on to trigger the inverter out of sleep then run the water. I know that the Takagi vent fan runs for a bit after you turn the water off, so it should keep the inverter out of sleep mode it you turn the water on and off for dishes for example.

    Beware that most direct vent water heater vent systems are very expensive, as opposed to simple "B" vent for the older design types, (Paloma legacy series, bosch aquastar, etc). If you only have to direct vent out the wall and need a elbow and a hood it is not too bad, but if you need multiple feet of pipe it gets pricey real quick.

    Tonyt
  • rickeolisrickeolis Solar Expert Posts: 110 ✭✭✭✭
    Re: tankless water heater off gird

    Consider this setup too:
    I have a Bosch 1600h that uses a pilot and I run it off a medium sized propane tank that sits near it. It works for the whole house just fine (2 adults, 4 kids) and compliments our off-grid living very well.

    -Rick-
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: tankless water heater off gird
    icarus wrote: »
    I have used the Takagi TK Jr with great success ON GRID.


    Tony,

    Have you ever used your kill-a-watt meter on the Takagi? I'm looking for a tankless system for an off-grid application that will eventually be preheated by solar. I'm willing to add some load to the inverter in order to get the output based temp control, but 60W seems excessive depending on how long it uses said 60W.

    Thoughts?

    Thanks!
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    No,, but I can make a call and have a result in a few days! Of course it will depend on how often the water gets run.

    Tony
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: tankless water heater off gird

    Tony,

    I hate to have you go through the trouble, but I sure would like to know the standby and running draw. :blush:
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    One day, with 2 people, very light day of usage= 0.11kwh,,, or 110wh. The Takagin draws ~4 watts on standby.

    Second day,, also very light,, total of .25 kwh

    Fourth day,,, .43kwh after 91 hours,

    Looking like about ~.12kwh day. Pretty light load however.

    I'll up date this post in a few days.

    T
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: tankless water heater off gird

    Thanks! I'll be looking for it.
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    So here is the update,

    .69kwh after 6 days. Seems like between .1-.2 per day would be a good average. Add a family of 4 with lots of showers, lots of laundry, and I think you should double it. 100-200 wh/day is not an insignificant draw on a small system. As I have said before, we use ~4-600 wh/day TOTAL average, that would be more than a 20% increase. I guess what you gain by losing the pilot light and the combustion fan,, you have to give give back in whs.

    Hope this helps.

    Tony
  • bentherebenthere Solar Expert Posts: 113 ✭✭✭
    Re: tankless water heater off gird

    Thanks Tony!

    I'd be okay with a pilot. What I want is adjustment based on output temperature.

    You do solar water preheating also, don't you? Do you just manually adjust the burner on your ph6?
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    At present,,, I do not do solar pre-heat on the PH6. I have significant freeze issues that, and the parasitic energy required of a circ. system makes it problematic. I should do a batch preheat in the summer, because that would be simple to do, but in point of fact, we only use hot water in the summer for dishes. Outdoor wood fired hot tub, and the lake keep us clean. Laundry is on a different summer water system,,, sort of complicated now that I think about it!

    In the summer, the water (lake) temperature rises to 60-70f. Then we dial down the burner on the Ph6. Even in the winter we don't have to burn it full bore to get it hot enough.

    Supposedly, the PH12 models will self temper, but I don't think they do it very well. I think the best way is to make sure that every critical faucet is two handled, so that you can micx the hot and cold as needed. I have a single handle on the kitchen sink, and wish I didn't. In the shower,, it is an absolute must.

    On the other hand, the Takagi works great, and tempers automatically. We have a rental house in Maine that we use now and again for ourselves. We have a Takagi and it is magic!

    I also have built a couple of simple pre-heat solar systems in the Pacific NW and have used Takagis. Water inlet of 90f and the burner just purrs, water inlet at 50 and it roars. At 115 and it doesn't even turn on. Magic!

    Shout if you have other questions,

    Tony
  • icarusicarus Solar Expert Posts: 5,108 ✭✭✭✭
    Re: tankless water heater off gird

    Ben,

    Here is a link to the PH12M,,, modulating heater. I don't know exactly how it works,, and I know that these are out of production,, but some are still available.

    http://www.tanklesswaterheaters.com/palomaph12m.html

    I wouldn't worry about the out of production aspect,,, these have been made for so long,, spares will be available for decades to come. The only real spare that can't be fabricated easily from some other is the water control diaphram.


    T


    Tony
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