Running Water heater on inverter

[Freelander]

My water heater is a propane only unit. So I bought a 400watt 'HotRod' to convert it to electric. I also installed a 1500 watt inverter to run some things that need 110 to run.

I also have 400 watts of solar and 300 amps of lithium batteries.

Starting yesterday I am running an experiment by running my water heater off the inverter. I can make enough electric to power everything I need, so I am trying to find ways to save on propane usage.

This is the kit I bought.
https://www.amazon.com/gp/product/B002SSIBSA/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[bullfrog]

Let us know if that works. For years we have used a under sink 10 gallon 120 volt electric water heater designed for garages while plugged into grid power.

 

[justanothermaroon]

I use that plugged into my Bluetti. Works fine. I don't leave it on all the time, of course.

 

[Freelander]

Most 110 v water heaters use a 1500 watt element, this add-on unit is only 400 watt it takes a while but it will heat it up.

So far my solar/battery system is handling it just fine.

 

[Freelander]

Well it ran the battery down to far, so its back on shore power.

 

[bullfrog]

Creating heat with electricity requires a lot of panel and storage. We used a “hot rod” (120 volt heating element that replaced the drain plug) when we still had a motorhome with an RV hot water tank and it only worked well while plugged in to a generator or shore power. Thanks for letting us know!

 

[JDub]

I really like my propane on demand heaters. I have a small one for the road and a bigger one on my deck. They work well and provide more than enough hot water for showers and washing dishes - I use a rechargeable pump for water pressure. Don't use too much propane either. Trying to run an electrical heating element off solar seems less then efficient IMHO...

Cheers.

 

[tx2sturgis]

Found this late...yeah that wont work unless you have a boat-load of excess solar and battery capacity.

 

[jimindenver]

I used a Hott rod in my 6 gal water heater since 2016. I had enough solar to run it during the day without draining my battery. It took two hours to heat cold water up to the 140 degrees I had it set to and about a hour to be warm enough to shower. I was not able to leave it on 24/7 until I got 400 Ah of lithium battery.

I recently upgraded the water heater to a dual heat with both propane and a 1440 watt heating element. It uses more power running but takes only 40 minutes to fully heat the tank. I also recently upgraded from 1185 watts of solar to 1935 watts so I can cover it during the peak of the day. It takes roughly the same amount of power out of the batteries to keep it warm over night as it does to heat it up in the morning.

I have customers with as little as 600 watts of solar and 400 Ah of lithium run their electric water heater early and allowing the solar to replace the power the rest of the day.

 

[afblangley]

I am working on addressing the same issue. My plumbing system is extremely simple: 7 gal Jerry can connected to a battery powered faucet. It has worked flawlessly over the past 9 months, but it would be nice to have hot water for washing hands, doing dishes, etc.

I don’t want to store hot water, I want it produced when needed. I don’t have propane in my van, but I do have a decent size power station. Operating under the principal of keeping systems as simple as possible, I bought an instantaneous hot water faucet. I think using this will be like my microwave: a high power draw for very brief periods of time, thus ultimately modest power consumption.

https://www.homedepot.com/p/ATMOR-1...er-Heater-Faucet-Plug-In-AT-2TAP-HD/315005220

 

[bullfrog]

The reviews look like it draws so much power the internal wiring eventually melts and a low pressure water source would make that happen sooner I would think. Good luck! Let us know how it works! Over many years people have been trying to make an all solar camper which would be really nice if it was possible and practical, Most heat producing appliances just have too high a power demand and the space and weight demands of the solar system becomes to big to deal with for most.

 

[Frood]

I have to say that I'm really getting a lot out of this thread... But from reading what everybody is saying it is looking more and more like a Joolca is going to be the right choice for me since I can heat up only the water I need with the pump that it uses... (Bob did a review on it once, and it looked pretty good).

 

[tx2sturgis]

So there ya go. Between 600 watts to around 2000 watts of solar panels, and something like 400 ah of battery capacity.

Give or take, about $2000 to maybe $5000 worth of hardware to save a few dollars worth of propane per week.

Yeah, if you already have all that capacity and make use of it in other ways, (cooking, A/C etc) then sure, it will work but buying and installing all of that JUST to have a warm shower every other day is not really practical.

 

[Freelander]

I thought I would try it and see what happened. I'm getting back into Boondocking mode. I plan to leave Houston on the 2nd of May and head north.

 

[jimindenver]

Every time I discuss what I can do with my solar system I hear that I spent a lot of money just to be able to save a few bucks in gas or propane. While I did design the original system of 750 watts to provide enough power to run a 5000 Btu window shaker during the peak of the day without draining the batteries, I knew that I would not be running that A/C all the time. So I found other things that I needed that would run off of the same amount of power.

The Hott rod uses roughly the same amount of power. Propane water heaters use more than a few penny's worth of propane.

The small burner on my electric stove uses 470 watts, Not as big as a savings but still better than nothing if you already have the power.

I have two small heaters and a electric blanket. A 250 watt ceramic for only when I use the bathroom on cold mornings, a 400 watt oil filled that helps keep the furnace off on cold, sunny days and the blanket lets me keep the heat down at night.

There are a host of other things it provides me for. The microwave is a given. A toaster is a wonderful thing as is my electric Moka pot. (coffee) Add in the fans, freezer, tools, computers, hotspots, TV, etc

The real upside is that by not only keeping my batteries properly charged I am not cycling them as I run these things for the better part. Cycling is how the batteries wear out and my bank was 11 years old before one of the batteries gave out.

The last thing that I don't think people take into consideration is that not only do I save money on the gas or propane it takes to run things, I save gas and time going to town to buy more gas and propane. In some places the run to town can be a lengthy one.

The one thing that I do not tend to run off of electric that I could is the electric side of my propane fridge. It takes very little propane compared to even one run of the hot water heater, Electrically it takes as much power as running the little A/C all day. In that case it is better to burn the propane and use the electricity for better things.

 

[tx2sturgis]

Jim, your system is exceptional. But the OP has 400 watts of maximum total solar input, with little to no 'excess capacity' to divert to trying to heat 6 gallons of water even a few times a week.

When I recommend that his system is not really suited for year-round solar water heating, that is applicable to the OP. If someone else has a system with 4 or 5 times that much solar input, then the answer is of course, different.

Having said that, in the summer time when the ambient water temp in that hot water tank is already sitting at 80 degrees or so, and the OP will have some excess solar input over and above the basic needs, then it might 'possibly' be able to warm the water up 20 degrees or so during the mid-day time frame and still 'possibly' maintain full battery bank voltage.

I prefer to heat water directly, either with a solar camp-shower bag, or the flame of a stove or propane water heater. On the other hand, with a small to mid-sized solar array, indirectly heating water with solar PV panels, solar charge controller, battery storage and then energy retrieval, leaves a lot to be desired, unless you have a LOT of excess capacity.

 

[Freelander]

I tried this to see if I could it more than anything else.

 

[tx2sturgis]

BTW you can buy 12v heater elements, this will boost conversion efficiency a bit. On the other hand, there will be no automatic cut-off when the battery gets low.

 

[dustytrailhead]

I have considered heating up 3 quarts of water on the induction cooktop and mixing it with cold water in my 2.5 gal. Nemo. I’m just not sure if that would be satisfying, 3 qts. boiling water diluted in 7 qts. cold. I don’t “need” hot water to wash anything else except my body. Showering with the Nemo is a half day project. I set the Nemo out in the sun out of the wind, wait at least 3 hours and, voila! (ha-ha), you have 80+° water. Then there’s the setup of the shower tent…I use the Nemo as a last resort.
I went solar for cooking and don’t use propane, so the only fuel I use is gasoline to heat the van and to power its engine. Webasto makes a water heater, but that is diesel. I would need to buy a diesel van. But, diesel and gasoline are readily available. Propane is not. I won’t waste time hunting propane for something that provides so little value to me.

 

[bullfrog]

Propane isn’t that hard to find in the Southwest. Most truck stops, hardware stores and dealer suppliers will fill tanks or exchange tanks. Swan’s trucks make deliveries to most of the Southwest and use propane. Any area that caters to the RV crowd will have several propane dealers. Most likely any fuel stop will have or know where to get propane.