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TranquilMan
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# Posted: 9 Nov 2016 10:39pm
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I need some suggestions for improving my hot water system. I finally have my wash house finished and everything works great – almost that is - so I’m looking for a little advice for changes to get it right next year.
We are off-grid so rely on solar power. My objective is to keep things simple and minimize our use of water and power. After 23 years we have upgraded by building a separate building (8’x10’) close to the cabin that contains a compost toilet, sink, shower, small propane freezer and a storage cabinet.
We draw water from a lake and for the past 23 years have had a gravity feed water supply. It consists 375 L tank that I fill with a ½ HP electric utility pump powered by my Honda 2500 generator when empty on a slight hill and 8 ft. high tower. A water line from the tank to the kitchen sink is all we had or needed for the past 20 years. We heated our water on a propane stove in a 10L pot. We have an outdoor shower which is great as long as the bugs aren’t bad, isn’t raining or too cold.
Last summer, with completion of the new wash house, I installed a 12 VDC Shurflo pump to supply water to the cabin kitchen sink, wash house sink and indoor shower. The pump intake line is ½†with a coarse screen at the inlet on the lake bottom (~12’ deep). The lift from water level to the pump is about 4 ft. I have a finer mesh filter on the pump intake. On the discharge side I have a pressure gauge and a 5 gallon pressure tank. The discharge line to the cabin is 5/8†and 125 ft. in length. The head from the pump to the highest device is about 20 ft. I installed a pressure gauge at the top end as well. The pump has a shutoff set at 45 psi. I lose about 12 psi with the lift. The pump delivers 10 L/min (2.6 GPM US) at the cabin. So far so good. I was thrilled at this point to have water on demand driven by the sun.
The next step was to install an on-demand water heater. After reading a lot of the blogs last winter, I bought an EccoTemp L5. I’ll now share the pros and cons of my system and ask for advice on how to improve it.
In July, I ran a test before plumbing the heater in. I set the heater up in the yard, connected to water and ran it full out for 10 min to test the pump, the battery, flow rate and temperature. It ran perfect. The flow and temperature were perfect for a shower.
In early August, I ran a longer 16 minute load test to check out the battery that runs the pump. Perfect, steady 8.0 L/min (2.1 GPM US) through a shower head with no voltage drop in the battery.
The next step was to plumb in the heater to give hot water to the kitchen sink, wash house sink and shower. I installed a pressure gauge and in-line filter ahead of the heater. It was now late August. It worked perfect! My wife loves the new shower. I still use the old outdoor one.
Now for the cons.
1. If she is in the shower and I run the kitchen tap, the flow to the heater can drop off below the minimum required for the heater and the heater cuts out. This is a slight inconvenience but we can live with that by communicating our shower use.
2. My wife likes a shower at about 40o C (104 F) and I like 43o C (109 F). We were happy with the results from the July and August tests for washing and showering but we like the water hotter for doing dishes. Still better than before.
3. In September the lake temperatures drop and so does the hot water temperature. Because I lose about 12 psi on the lift, and if I drop the flow rate to get the temperature up then the heater sometimes cuts out. Not nice if you are in the shower all soaped up.
4. Our cabin use is seasonal so it may mean that this heater will under-perform in May, September and October when the water temperatures are colder..
Anyhow, I love to hear form other experiences. I may have to go with a different heater and relegate this one to my outdoor shower that is at a lower head location.
Tranquil Man
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razmichael
Member
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# Posted: 10 Nov 2016 12:13pm
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You have done a lot of good experimentation! My system is kinda like this - I pump water from the lake to a rain barrel using a gas pump when needed. This feeds thru a strainer and 12V pump (can't recal the model but suggested but I got it as a package with my L5). Output splits with cold going to a "manifold" while the second split goes through the L5 and then to a "manifold". The manifolds are just 4 way brass hose manifolds. I do not use a pressure tank, although the pump does have a pressure switch built in. Currently I only feed a shower and one sink and all faucets have micro switches so, turn on a faucet and the pump comes on.
I think, as you note, that having more than one tap running will be limited with a small pump and the size of the L5 - especially true if you also have a cold tap on at all since all taps share the same limited pressure. You can try adjusting the pressure cut-out for the L5 as per these instructions Pressure Adjustment which might give you more range.
If you really want more hot water output you certainly have some other options but hard to tell what would work best and be the most cost effective. To increase the water available to the L5 you might be able to add a second pump and to boost the output to the L5 - might work although you would need to make sure the primary pump could keep up. Perhaps a larger main pump and use the current one between the pressure tank and the L5 - the built in pressure switch would only kick in when a hot water tap was open.
As far as temperature rise in colder weather I did consider two options - firstly add a second tank (insulted) and plumb it so you can circulate the water back into it from the L5 as a pre-heat (just a hot water tank but heated from the L5 when needed to pre-heat the water). This would obviously require manually preparing it once in a while depending on the size of the tank and the use. Another option would be to use a DIY solar water heating to pre-heat the water. Fun to do (I did something like this a few years ago for my Horses water trough) and surprising how much you could pre warm the water for no energy cost. There are a whole lot of DIY projects (some good, some not so good) at Solar Water Heater. Might be cheaper and easier to just add a second heater? You could keep the first one in-line set low to conserve fuel and let it pre-heat for the second.
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Atlincabin
Member
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# Posted: 10 Nov 2016 12:46pm
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Our cabin has a broadly similar system. We draw water from a spring, which is then gravity-fed about a km to our cabin with about 12 psi at the cabin. Incoming water goes through a sediment filter and then a ceramic filter (probably not needed but just in case). The flow is way too slow after going through the filters to do much with, but it is sufficient to trickle into a 30-gallon poly tank we have in the loft area of the cabin. We use a small float-type valve to automatically shut of incoming water when the tank is full (think toilet tank float). From there, we have a shurflo pump to pressurize the house and a similar (EZTankless 110) on-demand heater. The advantage of this system is that the water is always preheated to approximately room temperature or a bit higher (since it is in the loft). Even in cold weather, our heater is plenty sufficient to boost water temperature high enough to not want your hands in it.
Might or might not be useful in your situation.
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TranquilMan
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# Posted: 10 Nov 2016 01:25pm
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Thanks so much Atlincabin and razmichael. These comments are very helpful. I'll add a few pictures and details that may help tease out more ideas and hopefully a few more responses. I am wishing now that I had installed the water pump and heater to the cabin before designing and building the wash house to "test drive" the system first. Hopefully this bit of advice will help others. One final comment is that in our remote, off-grid location our goal has always been to seek out energy efficient, environmentally friendly solutions that are elegant, simplistic and cost effective to achieving a tranquil lifestyle. We are in an "unincorporated area" and so by keeping our water use to a minimum are allowed an outhouse and grey water pit so no septic field or holding tank required. We added a composting toilet a couple of years ago which has been a great addition. Anyway, more later.
Tranquil Man
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