Water heating without charge controller or batteries
- Thread starter Rikki
- Start date
BarracudaBob
Harvesting free photons from clean fusion
I replaced my water heater a few years ago. I regret not getting a high efficiency heat pump design. Especially now that I could have run it on solar AND cool the room where my batteries are. We are in a miserable heat wave in Florida right now. I had to put a fan in that room to keep them in the mid 80's.
Goodness gracious… stop complicating this 
……
it’s a damn 55 gallon barrel with a loose lid…. It is not a water heating tank… there will be no steam, there is no valving, there is no plastic piping to melt….
It’s a cauldron of warm water that’s heated ….it has a 3.5 GPM Shureflow pump picking up water when I need to use it through a pick up port…near the bottom…
It’s meant to generate enough warmish water to spray cow shit off the floor…or some shovels …boots …etc.etc etc..
It’s not a new Victron unit I’m thinking about bringing into mass..production…
All I was asking was why would i regulate somthing for safty when there is no danger of hot water exploding or doing anything anything…
Some things in life are simple … just simple…
J.
…
……it’s a damn 55 gallon barrel with a loose lid…. It is not a water heating tank… there will be no steam, there is no valving, there is no plastic piping to melt….
It’s a cauldron of warm water that’s heated ….it has a 3.5 GPM Shureflow pump picking up water when I need to use it through a pick up port…near the bottom…
It’s meant to generate enough warmish water to spray cow shit off the floor…or some shovels …boots …etc.etc etc..
It’s not a new Victron unit I’m thinking about bringing into mass..production…
All I was asking was why would i regulate somthing for safty when there is no danger of hot water exploding or doing anything anything…
Some things in life are simple … just simple…
J.
…
Gold Country Russ
New Member
I didn't know it was a barrel. However, I certainly don't want anybody to convert an AC water heater to DC without understanding that the thermostats will not work and that a suitable high amp DC contactor or relay must be used to stop, start, and control temperature. Whenever I see a similar post, I will check to make sure they know the hazards.
With a random heating element it would not work, for a reason I wrote in post #14.
Matching your heating element carefully with your panel it would kind of work, but not getting out the full potential of your panel.
In case, that energy was wasted anyway, it could be acceptable result.
Ahhh, simplicity …in a positive light…..thank you..
DPC
Solar Enthusiast
No it won't.
Those things are ratted to switch 3000 watts at 240 volts.
Those contacts will not be harmed by 12 or 24 volt DC switching 300 watts.
but I would be inclined to heat water directly with the sun through a home brew copper heat ex changer and pex pipes well insulated.
Search Aliexpress for 12 volt ball valves and pumps as required.
Zwy
Emperor Of Solar
Do it and let me know how it works out for you long term.
Only takes once to make the potential rocket ship. Enjoy the ride.
Zwy
Emperor Of Solar
Goodness gracious… stop complicating this
it’s a damn 55 gallon barrel with a loose lid…. It is not a water heating tank… there will be no steam, there is no valving, there is no plastic piping to melt….
Loose lid and 55 gallon barrel with no insulation- good luck with holding heat. You might as well go pee against the wind, it would be about as useful.
Water evaporates and takes heat with it. Raise the temp of water and the rate of evaporation increases. Without a sealed insulated lid, good luck.
Paint the barrel black, let it sit in the sun. It will work much better. I guess I'm just an old guy that learned a few things along the way.
Or use the electric power to run a pump that circulates water thru a 50 foot black hose to and from the tank. I have a water tank on the work truck with a short hose. I use it washing my hands and cleaning heat exchangers. The water in the hose is always nice if the sun is out.
The issue is there is not anything safety related in place if an electric hot water heater is used. If there isn't any hot water use over several days, the tank temp will increase each day as hot water heaters do not lose heat very fast. There has to not only be a system in place to control temp but also pressure. As temp rises, pressure will increase until a point of criticality is hit.
I already stated what I thought about using a 55 gallon uninsulated open lid barrel.
Safety comes first, regardless. It can be simple and safe.
Gold Country Russ
New Member
The thermostats have short throw AC contacts that have no arc quench, on DC when the contacts open, they can continuously arc, and you won't ever know it until too late. You will need something like a Littelfuse DCN high voltage DC contactor. To effectively use an AC water heater on DC may involve a string of 3 or more panels with voltage well over 100. Note that most arc welding is at about 24 volts.
Last edited:
grebaba
New Member
In Nam the army had canvas showers.
They were black colored and installed on a framework to hold them up.
I would guess they held 250-500 gallons.
With only the sun to heat them they worked great, however I don't know how good they would work at 10 below.
Greg
They were black colored and installed on a framework to hold them up.
I would guess they held 250-500 gallons.
With only the sun to heat them they worked great, however I don't know how good they would work at 10 below.
Greg
Doggydogworld
Solar Enthusiast
- Joined
- Aug 29, 2022
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- 365
The $10 camp showers at Walmart hold a bit less.
Loose lid and 55 gallon barrel with no insulation- good luck with holding heat. You might as well go pee against the wind, it would be about as useful.
Water evaporates and takes heat with it. Raise the temp of water and the rate of evaporation increases. Without a sealed insulated lid, good luck.
Paint the barrel black, let it sit in the sun. It will work much better. I guess I'm just an old guy that learned a few things along the way.
Or use the electric power to run a pump that circulates water thru a 50 foot black hose to and from the tank. I have a water tank on the work truck with a short hose. I use it washing my hands and cleaning heat exchangers. The water in the hose is always nice if the sun is out.
The issue is there is not anything safety related in place if an electric hot water heater is used. If there isn't any hot water use over several days, the tank temp will increase each day as hot water heaters do not lose heat very fast. There has to not only be a system in place to control temp but also pressure. As temp rises, pressure will increase until a point of criticality is hit.
I already stated what I thought about using a 55 gallon uninsulated open lid barrel.
Safety comes first, regardless. It can be simple and safe.
…….have a nice day…I was writing about relay, not thermostat. If a relay is rated for 250VAC / 30VDC, either I can use it for <30VDC, or I can't use it even for <250VAC.
Even a thermostat at AC is going to fail after switching x times. That's why you can't setup a water boiler without pressure valve, better even two of them.
efficientPV
Solar Addict
- Joined
- Sep 24, 2019
- Messages
- 1,449
Everyone should be aware that when the contact opens, the switch sees the open circuit voltage of the panels. That is why the MW&S thermostats blow up when used on 24V panels. With low voltage elements, you can lose half the power just getting to the heating element. With all this interest in simplicity, I don't see why people don't just use knife switches to charge batteries.
Important point to remember!
Not just for thermostats, but for everything related to solar setups. Everything has to be rated to open circuit voltage.
DPC
Solar Enthusiast
I bet you a pound of bacon your wrong and have never done anything like this....
You might need a DC rated contactor if this was an inductive load but its not.
A 300 watt electric element at 24 volt is far more realistic and practical, will have horrible recovery time but will keep warm up a 45 gallons of water.
Better its there to compliment a solar water heater or alternative heat source
If the sun doesnt shine.
A jacket heater will warm water too.
( not this one, its a rust bucket but you get the idea )
Gold Country Russ
New Member
Years ago, Missouri Wind & Solar really was pushing DC conversions of water heaters. They offered a DC rated contactor specifically for the application and enough data to prove exactly why the AC contacts were unsafe and would fail. They convinced me. That part and its supporting documents are long gone, I suspect over legal issues. They still sell DC heater elements but nothing else.
Later this year I will be converting a slightly used electric water heater to preheat water w/either 116V 1.2kw or 155V 1.6kw PV before feeding into the existing propane water heater. If I choose to use the existing thermostatic contacts it will be with 24vdc control voltage for a DC high voltage contactor similar to a Littelfuse DCH series or equal. This will be the only PV DC I allow in my house, and I will make certain it is 100% safe.
Later this year I will be converting a slightly used electric water heater to preheat water w/either 116V 1.2kw or 155V 1.6kw PV before feeding into the existing propane water heater. If I choose to use the existing thermostatic contacts it will be with 24vdc control voltage for a DC high voltage contactor similar to a Littelfuse DCH series or equal. This will be the only PV DC I allow in my house, and I will make certain it is 100% safe.
I agree 100% with you, with those voltages at DC you don't have other options. But in case of 12/24VDC situation is different.
Anyway, all relays and thermostats and contactors, AC and DC can fail. Many different ways and different outputs. In coil failure usually open, in contact failure often closed. AC relay or thermostat can fail closed by welding it's contacts, not so uncommon. So the youtube boiler rocket is ready to launch...
In case of continuous Dc arching inside a relay, I would expect the relay body melting and putting your house in fire before your boiler explodes.
Safety pressure valves are always needed, AC or DC or solar thermal.
DPC
Solar Enthusiast
If it bothers you us the thermostat in the tank to run a DC rated relay.
Little fuse bought a Canadian company that used to make special relays I use a lot.
Closed up everything is Saskatoon where the relays were made and moved to the USA where they employ god knows who from god knows where to make an American Analog of the same part.
call them for tech support and they will tell you its a magic relay that does everything.
I don't begrudge Murf for selling out.
But he could tell you what the really really did. ( and I knew him back in the day a very smart engineer )
Little fuse will tell you what they think it could do if you buy it...
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