Water heating without charge controller or batteries

[BarracudaBob]

Just asking…. Why if the power is no where near enough to overheat anything would one need a thermostat… let’s say you only wanted a moderate boost in temp ( for what ever reason ) ,,?

Why not just let the panel(s) just produce all they can and then let it cool a bit over night and start again the next day….

I have wondered this too but never dug in deep enough to find out the detail..

Experiment and find the amount of panels needed to reach a pre determined temp in perfect sun conditions with the right size heater element for the water volume and then let it roll …simple rig… maybe adjust the number of panel seasonally …

It’s Gona turn off anyway every afternoon… if it maxes out at ,(let’s say 130F,) why regulate it .. it’s nowhere near dangerous

I can think of a few uses for moderately hot water in a shop …

I’m sure I’m missing somthings, but what…!
J.

When a switch opens DC it want to arc longer than a AC would. Mechanically they usually switch faster and contact travel farther away. Look what inverters are doing. They switch DC high current all the time. I can be done just don't use a AC device for DC. There are also ways to do it what a "snubber" capacitor to take the surge. For safety use a fuse and some sort of thermostat.

Here is another link to components: https://www.hurricanewindpower.com/dc-water-heating/
Amazon also sells DC water heater elements. I guess it is a thing.. I also watch a couple that use a solar dump voltage controled relay. When the batteries reach a certain voltage they dump the solar into the water heater. This way you can use the same panels for two different purposes.

 

[JRH]

When a switch opens DC it want to arc longer than a AC would. Mechanically they usually switch faster and contact travel farther away. Look what inverters are doing. They switch DC high current all the time. I can be done just don't use a AC device for DC. There are also ways to do it what a "snubber" capacitor to take the surge. For safey use a fuse and some sort of thermostat.

Here is another link to components: https://www.hurricanewindpower.com/dc-water-heating/

Hmmmm , not sure if I wrote it wrong or you misunderstood my question.… in my scenario there is no switch’s or inverters or anything but some panels wired for the need - 2 wires - a heating element - a tank .

That’s all…

yes I would probably wire in a dc fast action switch just to disconnect if need be…

If it never got over the desired temp running wide open all sunny day , why would I need a thermostats at all…

This is a total off grid distant barn concept where there is no other power available, that’s why I’m asking… why would I regulate somthing that is happy doing what it does 6-7;hours a day..be it 100 degrees orv140; degrees it would be very usable..

 

[BarracudaBob]

Hmmmm , not sure if I wrote it wrong or you misunderstood my question.… in my scenario there is no switch’s or inverters or anything but some panels wired for the need - 2 wires - a heating element - a tank .

That’s all…

yes I would probably wire in a dc fast action switch just to disconnect if need be…

If it never got over the desired temp running wide open all sunny day , why would I need a thermostats at all…

This is a total off grid distant barn concept where there is no other power available, that’s why I’m asking… why would I regulate somthing that is happy doing what it does 6-7;hours a day..be it 100 degrees orv140; degrees it would be very usable..

It was a new cool subject for me to look into. I didn't know it was a 'thing' but now I do. Just sharing some though.

 

[Gold Country Russ]

Just asking…. Why if the power is no where near enough to overheat anything would one need a thermostat… let’s say you only wanted a moderate boost in temp ( for what ever reason ) ,,?

Why not just let the panel(s) just produce all they can and then let it cool a bit over night and start again the next day….

I have wondered this too but never dug in deep enough to find out the detail..

Experiment and find the amount of panels needed to reach a pre determined temp in perfect sun conditions with the right size heater element for the water volume and then let it roll …simple rig… maybe adjust the number of panel seasonally …

It’s Gona turn off anyway every afternoon… if it maxes out at ,(let’s say 130F,) why regulate it .. it’s nowhere near dangerous

I can think of a few uses for moderately hot water in a shop …

I’m sure I’m missing somthings, but what…!
J.

With no demands you may make steam, melt plastic piping, suffer steam or hot water burns or with the failure or lack of a T&P valve have an explosion. Overheated water heaters were the MythBusters favorite episodes, very impressive and even more dangerous.
Search on YouTube for MythBusters exploding water heater episode.

 

[BarracudaBob]

With no demands you may make steam, melt plastic piping, suffer steam or hot water burns or with the failure or lack of a T&P valve have an explosion. Overheated water heaters were the MythBusters favorite episodes, very impressive and even more dangerous.

I love that episode

 

[JRH]

With no demands you may make steam, melt plastic piping, suffer steam or hot water burns or with the failure or lack of a T&P valve have an explosion. Overheated water heaters were the MythBusters favorite episodes, very impressive and even more dangerous

 

[BarracudaBob]

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.

 

[JRH]

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.

…

 

[Gold Country Russ]

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.

 

[kmin]

in my scenario there is no switch’s or inverters or anything but some panels wired for the need - 2 wires - a heating element - a tank .

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.

 

[JRH]

In case, that energy was wasted anyway, it could be acceptable result.

Ahhh, simplicity …in a positive light…..thank you..

 

[DPC]

AC water heater thermostats will melt, weld, or catch fire on DC power. Don't do it.

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]

No you don't. As mentioned normal AC relays are rated up to 24-30V DC.

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]

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.

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..

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.

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…

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.

Some things in life are simple … just simple…

Safety comes first, regardless. It can be simple and safe.

 

[Gold Country Russ]

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.

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.

 

[grebaba]

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

 

[Doggydogworld]

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

The $10 camp showers at Walmart hold a bit less.

 

[JRH]

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.

 

[JRH]

Gee, what a wonderful comment… thank you…… …….have a nice day…

J.

 

[kmin]

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.

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.