immersion heater low voltage

elheffe

hi
does anyone know of a site that offers 120volt immersion element heater. being looking for a long time and keeps getting muck websites. any help would be greatly appreciated.
thanks

2011

if all else fails, why not uses a standard 3 kW 230V immersion ? It will work as though it is a 1.5 kW element when connected to 120VAC. I know it will take longer to heat up, but you could just leave it on for longer (but the water might to get as hot as you want it to).

liveandnetural

will make you whatever you want
http://www.elemex.ie/index.html

Bruthal

2011 wrote: »

if all else fails, why not uses a standard 3 kW 230V immersion ? It will work as though it is a 1.5 kW element when connected to 120VAC. I know it will take longer to heat up, but you could just leave it on for longer (but the water might to get as hot as you want it to).

It will actually only be around 750 watts connected to half the 230v supply.

2011

Bruthal wrote: »

It will actually only be around 750 watts connected to half the 230v supply.

My bad, you are correct.

Bruthal

2011 wrote: »

My bad, you are correct.

I wonder what the application is.

elheffe

thanks all for the replies, great help. I am doing a project, using batteries to power an immersion. was thinking 120 volt system as i would like a big enough element. 12volt 65AH batteries 10 in series. liveandneutral cheers for the link never heard of them before so will check them out.

Bruthal

You could use 2011,s suggestion anyway., for the 750 watt output. Or 2 x 3kw 230v elements in parallel for 1.5kw output.

brightspark

Out of curiousity, how are you recharging the batteries?

Looks like you will get about 7.8kWh (65*10*12) from your batteries before they completely discharge. (just over 2 1/2 hours at 3kW).

Don't forget different batteries have different characteristics regarding the max current you can draw, and how rapidly the cells discharge at various discharge currents.

So it may be necessary to reduce the element wattage to suit the battery characteristics.

Bruthal

brightspark wrote: »

Out of curiousity, how are you recharging the batteries?

Looks like you will get about 7.8kWh (65*10*12) from your batteries before they completely discharge. (just over 2 1/2 hours at 3kW).

Don't forget different batteries have different characteristics regarding the max current you can draw, and how rapidly the cells discharge at various discharge currents.

So it may be necessary to reduce the element wattage to suit the battery characteristics.

If its car batteries used, they won't last long when discharged by more than 20 percent, in terms of charge cycles. Even deep discharge ones probably only have 50% useful capacity of the rated amount. Regular discharging beyond that will reduce the expected battery lifetime of charge cycles.

elheffe

the batteries I was going to use was sonnenschein 12v 56AH. gel type as they don't need to be vented I believe. have to rethink it as I would be looking at 10 batteries in series of two parallel strings, twenty in total. crazy price. probably will have to drop the size of element and reduce the system voltage from 120 volt to some a bit more realistic to be honest. its a learning curve. recharging batteries via a wind turbine. alternative energy aint cheap....... thanks for the replies.

Bruthal

It won't matter what voltage you reduce to, to get a given wattage for a certain time will still require the same amount of batteries.

10s 2p giving 120v would give 6.72kwh's per string, and so 13.44kwh's for the 2p (parallel)


But all 20 in parallel giving 12v will also have 13.44kwh's capacity, in theory anyway if batteries could be fully depleted.

So dropping the wattage would be the main factor, which happens anyway when you reduce the voltage to the same element. Half the voltage to a given element, and you half the current, and so quarter the wattage.

brightspark

Why not heat the water directly from the turbine?

Bruthal

brightspark wrote: »

Why not heat the water directly from the turbine?

It would seem sensible alright, although if the water was being heated for an hour a day, a smaller turbine can gradually charge batteries over the 24 hours, and batteries then supply the high demand for the short duration.

A well insulated cylinder and a smaller turbine can just gradually heat the water all day probably.

elheffe

heating directly from the turbine on such a big element creates a big resistance. the turbine wont rotate due to the high resistance attached. would this be a correct assumption. that's why I was choosing to power element by batteries.

Bruthal

elheffe wrote: »

heating directly from the turbine on such a big element creates a big resistance. the turbine wont rotate due to the high resistance attached. would this be a correct assumption. that's why I was choosing to power element by batteries.

Well the lower the resistance of the element, the harder it is to turn the turbine.

Like I was saying above, a small turbine can charge the batteries over 24 hours, and the batteries can release that energy quicker for a short period.

A lower wattage element would do the same thing, by heating the water slowly, once the heated vessel is well insulated.

2011

You could design it so that the load would come on gradually as the speed of the turbine increases with PWM and a speed sensor. If I was doing this I too would try to get rid of the requirement for batteries.