A little off topic...but off grid.. Low pressure tankless hot water heater

couchsachragacouchsachraga ✭✭Solar Expert Posts: 78 ✭✭
The system set up at my place is working so well my neighbor has asked help setting up something similar... but I'm at a bit of a loss the best way to go about it (I have plenty of ideas).

The problem he has is not a lot of sun; just enough to charge a small setup for a few lights (he's happy with this). If what I outline below does not work I'll look in to a booster pump and tank, but that will add a lot of complication and expense.

The goal is to add hot water (thus making his wife and kids happier, and more likely to want to join him there for a more extended time).

The tankless (propane fired) hot water heater I use needs at least 25 psi to operate.

I've noticed the EZ Tankless and Eccotemp units claim they can work on less (EZ Tankless rates 15-20 psi, but notes it can fire down to 2.9psi).

Is anyone using these, or other units in a low pressure situation, and how are they working?

I plan on measuring the actual pressure this weekend (ram pump to a storage tank on top of a hill that then gravity feeds to his cabin), but I'm guessing it will be 8-10 psi max.

Any experiences, including thoughts on the units listed above (even at higher pressures) would be greatly appreciated!

Comments

  • CariboocootCariboocoot ✭✭ Banned Posts: 17,615 ✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    There was just a discussion about tankless heaters and the Ecotemp was mentioned in it: http://forum.solar-electric.com/showthread.php?24150-Propane-Tankless-Water-Heater-Reviews&highlight=tankless
  • PlowmanPlowman ✭✭✭✭✭ Solar Expert Posts: 203 ✭✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    I have an Eccotemp L5. Listed pressure is 20-80 PSI. Doubt you'd be able to run it off <10 PSI.

    I have it plumbed into my RV, so I use it with a 12V pump and ~40 gal tank. Don't know what my water pressure is, but it's high enough to make the Eccotemp work fine.

    My RV's pump draws ~4.5 amps @ 12V, but because it doesn't run all that much, the draw from the batteries is not significant.

    The Eccotemp and similar tankless water heaters need to be vented outside. I have mine outside the RV with a piece of corrugated metal over it to keep it dry. I plan on building a full enclosure around it before the rains return this fall.
  • jonrjonr ✭✭✭✭ Solar Expert Posts: 1,307 ✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    If you want to avoid using electricity, then you might have the ram pump fill and pressurize a pressure tank. I have one big enough to take a complete shower with no pump.

    I am available for custom hardware/firmware development

  • couchsachragacouchsachraga ✭✭ Solar Expert Posts: 78 ✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    Interesting you mention a ram pump - that is how we get water up to his cabin at all. I checked the pressure that night... 14psi. I tried moving the cistern up the hill, but the longer pipe meant quite a bit less flow (doubled the length of pipe). In the end we put the cistern (35 gallon barrel) 20' up a hemlock on the top of the hill. Quite amusing seeing it strapped up there, but 22psi is the result.

    I went with the EZ Tankless 202, which claimed to work at 15 psi online... and says 35 psi in the enclosed literature.... It works, but not at full flow (the unit has valves for both water and gas). We turned the water down a bit for it to work, and the gas down all the way (so it wouldn't get too hot). An interesting note is it DOES work with full flow... out the unit directly, or even out a short pipe. But the kitchen faucet constricts the flow enough it doesn't work unless the water is turned down inside the unit. It took a bit of trial and error to figure that one out.

    My friend (and especially his wife and kids) are thrilled to not only have water in the sink (a rarity), but hot water too (a first in the 50 years or so that cabin has been there!)

    Thank you too, for the link - someone in my search I missed that. I was able to read it at a friends house, but didn't log in. Up where my place is and his cabin there is no landline nor cell service, and it is too mountainous for satellite... so no internet. Not always a bad thing!
  • SurfpathSurfpath ✭✭✭ Solar Expert Posts: 393 ✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater
    The tankless (propane fired) hot water heater I use needs at least 25 psi to operate.

    I've noticed the EZ Tankless and Eccotemp units claim they can work on less (EZ Tankless rates 15-20 psi, but notes it can fire down to 2.9psi).

    Is anyone using these, or other units in a low pressure situation, and how are they working?

    Any experiences, including thoughts on the units listed above (even at higher pressures) would be greatly appreciated!

    I have been using an Eccotemp L5 for the past 2.25 years on 21 PSI (+ or - a couple PSI). It will run one shower and has an automatic cut off after about 9-12 minutes (for some reason this cut off kicks in slightly sooner every month:confused:).

    The main thing you'll read about these units is that they are prone to flameout (I have mine mounted outside in a vented enclosure that prevents this). They also need to be temperature adjusted on the unit (you cannot adjust the temperature at the shower valve). At my lower PSI it is scalding when the knob is on (ROUGHLY) "4" out of 10. If you have hard water it may need periodic cleaning with a descaler such as vinegar (so I have heard, not my experience).

    For the first 14 months it worked great - no problems, but now it is a little temperamental. It doesn't seem to like low LPG tank pressure (I sometimes have to change my tank over to the kitchen or BBQ tank when it is only <20% full). Some days it just doesn't want to come on for whatever reason and I have to wait with the water running for 4+ minutes for it to kick in. Sometimes I need to go outside and fiddle with the gas & pressure knobs on the unit to get it to flame on.

    Bird's have tried to nest in it and I occasionally find dead lizards underneath. I should probably open it up and give it a clean:roll:.

    You get the drift: After a while it may challenge folks who are used to on-grid or on-demand hot water.

    We are being patient with it, but if my wife was not so easy going we would have replaced it 8 months ago. It is powered by 2 D cell batteries (I love this), It only cost $100.

    In sum I feel I have gotten out my money's worth but it is by no means perfect.

    If you have a whole house filter you may want to increase filter size to 10 microns+. This can also increase pressure. But overall, I think 20PSI should be no problem.
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
  • PlowmanPlowman ✭✭✭✭✭ Solar Expert Posts: 203 ✭✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    Thanks for posting about how the Eccotemp has fared over time, Surfpath. I didn't know it had an automatic cutoff, I guess I take short showers.

    I've found my Eccotemp L5 doesn't work reliably when the kitchen faucet is open just a little bit. I get hot water (eventually), but the temperature varies from scalding to lukewarm, and often it will cut off entirely. I think if I added an accumulator tank it might help, I don't think the Eccotemp likes the pulsation of the RV's water pump.

    I adjusted the unit so it would be right for taking a shower, when the water valves are wide open. It works pretty good for that, but I've noticed that once my water tanks heated up in the hot weather, the temperature of the water the Eccotemp was putting out became scalding in the shower. I can usually find a happy medium by slightly cracking the cold water valve. I expected this, it's not a big deal.

    Last time I adjusted it I had to exit the shower wet and run outside naked a few times. Rather not have to do that on a regular basis :)
  • inetdoginetdog ✭✭✭✭ Solar Expert Posts: 3,123 ✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater
    Surfpath wrote: »
    I have been using an Eccotemp L5 for the past 2.25 years on 21 PSI (+ or - a couple PSI). It will run one shower and has an automatic cut off after about 9-12 minutes (for some reason this cut off kicks in slightly sooner every month:confused:).

    Scale building up inside the heat exchanger??? Have you tried de-scaling it?
    SMA SB 3000, old BP panels.
  • SurfpathSurfpath ✭✭✭ Solar Expert Posts: 393 ✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater
    inetdog wrote: »
    Scale building up inside the heat exchanger??? Have you tried de-scaling it?

    Perhaps. I will descale as well when I do the cleaning. Good idea.

    It's really great when it is on a roll (has the right pressure, the knobs are at that magical position, no birds are nesting inside, etc).
    Sometimes this is for months.

    No need to run outside naked to fiddle about, right?

    Plowman: Off topic but curious: Do you have a fridge in your set up (run it on the genny?)
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
  • PlowmanPlowman ✭✭✭✭✭ Solar Expert Posts: 203 ✭✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater
    Surfpath wrote: »
    Plowman: Off topic but curious: Do you have a fridge in your set up (run it on the genny?)
    I have a 2-way RV fridge, run on propane. Requires a small amount of 12V to power the controller (draws max of 0.3 amps, often nothing at all). I also keep a chest freezer in a friend's barn nearby (run on grid power).

    Do you have a good sense for how long the D batteries last in the Eccotemp when using it daily? Have you ever tried AA inserts? I'd like to find a rechargeable way to run the igniter and don't want to invest in D battery chargers.
  • SurfpathSurfpath ✭✭✭ Solar Expert Posts: 393 ✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater
    Plowman wrote: »
    I have a 2-way RV fridge, run on propane. Requires a small amount of 12V to power the controller (draws max of 0.3 amps, often nothing at all). I also keep a chest freezer in a friend's barn nearby (run on grid power).

    Do you have a good sense for how long the D batteries last in the Eccotemp when using it daily? Have you ever tried AA inserts? I'd like to find a rechargeable way to run the igniter and don't want to invest in D battery chargers.

    Good question. I just thought about that a few days ago. I find the D batteries (alkalines) last a fairly long time though. Perhaps 9-10 months per pair (using 1-2 ignitions a day). I once used "C" type AA inserts to light the unit up, and it worked (just line up the terminals & you are good to go).

    On a related issue: Our L5 unit is plumbed into our house hot water line outside the shower on the external concrete block wall. For the last 2 years we have left the unit on (ie the on/off switch left on, and the propane regulator left on). It's a convenience thing. After taking a nice shower you dont really want to walk in the dirt around to the back of the house in your towel to turn off everything. Conversely, when you come home at night from a hard day you don't wish to fumble in the dark out back to turn it on.

    We have experienced no problems, but occasionally when the -cold water- garden hose is put on full blast you will hear noises coming from the unit (2-3 seconds of water going through the unit, and one or two ignition ticks, then silence). I think turning on the cold sends a certain amount of (initial?) pressure through the hot line (and the unit). It has never ignited, even with the garden hose left on. But it has made me pause. Your thoughts?
    Outback Flexpower 1 (FM80, VFX3048E-230v, Mate, FlexNetDC) 2,730watts of "Grid-type" PV, 370 AmpHrs Trojan RE-B's, Honda 2000 watt genny, 100% off grid.
  • PlowmanPlowman ✭✭✭✭✭ Solar Expert Posts: 203 ✭✭✭✭✭
    Re: A little off topic...but off grid.. Low pressure tankless hot water heater

    I plumbed my Eccotemp into my RV, using the lines from the old leaky water heater. It clicks regularly when the kitchen sink's cold water valve is opened. Not sure why. It keeps clicking as long as I have any valve open, hot or cold, maybe because of the surge of my RV pump. The constant clicking makes me a bit concerned about battery life.

    I've been using mine for all my daily hot water for about ~3 months. I've never turned it off, I'd actually forgotten it had an off switch and had to go outside and look for it :)

    I have some Sanyo Eneloop D sized inserts for AA batts. I tried them in the Eccotemp when I first got it, but they didn't fit very well so I bought some alkaline Ds, which have lasted 3 months without issue. When they die I'll try the AA inserts again and make whatever modifications are required to make them fit. I regularly use AAs for other stuff and have a pretty good stock of rechargeables. Plus I don't like the idea of disposable small batteries.
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