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Topic: Water Heater (Read 7 times) previous topic - next topic

zhozer

Thank you for the answers.
I'd say I'm not a completely newbie, I know something about it.

@Techylah
I like your idea.
I will buy a LCD, so I can see the temperature. I pretend in the future make some modifications, but first I need to build a simple water heater to know more about it.

Do you think I can vary the tension applied to that heater with a potentiometer? To get a better tea, e.g. if I want some green tea, I'd would prefer to heat it slower.
Also, do you think I could touch that heater in a metal plate like a cooker, and use the plate to heat the kettle? I think with that arrangement I would make better teas since has some controversy about the ways electric heaters are made.


Techylah

#16
May 22, 2012, 01:08 am Last Edit: May 22, 2012, 01:17 am by Techylah Reason: 1
Quote
do you think I could touch that heater in a metal plate like a cooker

No.  I think that is ill-advised.  It is made to be immersed, which provides a solid, low thermal resistance connection to the heat absorbing object, the water.  It would probably overheat and burn-up in flames if not immersed.

Instead, use any regular electric teapot.  The electric and mechanical connections to the heating element are done.

Your device can look like a stainless steel spoon that you leave in the pot.  Of course it has digits on top and a wire going to your Arduino to bring it to and maintain the temperature you want by cycling power to it via a relay.

I don't know much about tea, but if it is like coffee, heating time doesn't matter.
It is only the final temperature that will affect flavor.  I think the better flavors come out at lower temperatures; the bitter components take longer and require higher temperature.
If this is so with tea, making tea at lower temperature but longer steep time, would be better and worth the effort.

You'd still want to reach the lower temp as soon as possible, so the relay is best.
Besides dealing with SCRs and other high voltage, high current "dimming" circuits is tricky.

Your Arduino could also handle the steep time with finesse.
You put your "magic spoon" into any size electric pot, plug the pot into your switched power outlet, and press Start.
You get to watch the water get up to temp as soon as possible, (a settable 85 deg C), give you a "Bong" to add your tea,
and then another "BingBong" x minutes later when it's done!  Then it maintains that temperature.

With your pot, potentiometer, that is, you can set the default temperature and steep times.

Chagrin


there was a good reason i advised the use of peltier junctions for this project as  the highest voltage  one may come in contact with  is dependent on the  junction used  but will  nearly always be below 60 volts dc

You know what happens when you drive an "AC" heating element with DC? ;)

PeterH


You know what happens when you drive an "AC" heating element with DC? ;)


It gets hot?
I only provide help via the forum - please do not contact me for private consultancy.

radman

Quote
controversy about the ways electric heaters are made


There is no controversy, just a warning that electricity is dangerous. Normally control circuits are separate and well insulated from power circuits, once you start introducing water there is a risk that people can come in contact with the effects of high voltages or currents.

You say you are not a complete newbie but it seems clear that english is our second language so just take care about safety.

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