school project to build up a little water heater

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  #1  
Old 03-02-14, 05:08 PM
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school project to build up a little water heater

Hello guys, I'm new to the site. I have a project to build a water heater than can heat up to one liter of water and keep it at 48 degree Celsius constant.

Any ideas how I can achieve that? I want to use a little stove burner and some thermostats and I need to figure out how I can wire it.

Thank you for your help.

Regards,

Thomas
 
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Old 03-02-14, 05:21 PM
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Welcome to the forums.

While we think about the project ...... what grade is this project for ?
 
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Old 03-02-14, 05:43 PM
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I won't do your engineering for you, but will throw out an idea or two to make you think. Since this is a class project and the teacher expects results you need to do the work yourself.

Now for a hint you need a thermostat that is "normally closed" and opens on heat rise. It will need to be in contact with the water that is to be heated and will need to be waterproofed in some way. That is your problem to solve. Next you need a heat source that can be controlled by the thermostat, eg. an electric hotplate. Now combine all this with a container and a reliable thermometer and you are in business. Might add insulation to container to hold heat in.
Here is a hint for a thermostat;
Amico 5 x KSD301 40C 104F Normal Close Thermostat Temperature Control Switch - Amazon.com

Good luck and do have FUN!
RR
 
  #4  
Old 03-06-14, 12:56 PM
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Hello guys,

thank you for the hints. I'm grade 10. The project is about how to keep water at a constant temperature because water loses temperature very quickly due to contact with the air.

The teacher told us to ask electricians and to go to forums like this one where more knowledgeable people can help us.

But I don't understand how to wire the thermostat. Isolation is a good idea. I will put sand or clay between the small and the big container. The water will be in the small container.
 
  #5  
Old 03-06-14, 03:39 PM
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Wiring thermostat.
You will need a two terminal thermostat. One terminal will connect to LINE Black the other terminal will connect to LOAD Black. It will be a temperature controlled switch for the black wire.
LINE White connects to LOAD White.
GREEN connects to GREEN or to metal frame of heater and/or tank to provide shock protection. This will plug into a GFCI receptacle.
Now I hope a resident ‘Sparky’ will jump in and correct/add to my statements. If they could furnish an easy to understand drawing it would help.
Your basic process is the closed thermostat will supply power to heating apparatus causing it to heat. When the thermostat (in contact with water) reaches cut-off temperature it will open its contacts stopping power to heating apparatus. When water cools to cut-in temperature it will close contacts supplying power to heater. This is an endless cycle repeating as needed.
Have fun!
RR
 
  #6  
Old 03-06-14, 06:35 PM
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Imho...

Thermostats in electric water heaters are usually external and NOT in contact with the water in any way. They depend on a heat transfer through the wall of the tank. This is a lot safer when working with electricity.

Also if you can not have access to a GFCI outlet for your project, think along the lines of those GFCI plugs that are on most hair dryers. They function the same way. If there is a difference between the current flow in either line, they shut off. This works without a third prong or ground and is just as safe.

Gerry
 
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Old 03-07-14, 01:59 AM
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The project is about how to keep water at a constant temperature because water loses temperature very quickly due to contact with the air.
Absolutely FALSE! The water loses temperature because it is warmer than the surroundings. Heat ALWAYS travels from a point of higher temperature to a point of lower temperature. It can do so in one, or more often, in all of three ways. Convection, conduction and radiation. Only the convection has anything to do with a gaseous intermediary medium.

If your teacher disagrees then he/she needs to do a bit of study of the laws of thermodynamics.
 
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Old 03-07-14, 09:14 AM
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Is school providing the thermostats or do you need to specify what you want?
If they are providing the hardware then we need to know what it is.
 
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Old 03-08-14, 10:58 PM
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Is school providing the thermostats or do you need to specify what you want?
If they are providing the hardware then we need to know what it is.
No, we have to do EVERYTHING by ourselves. All we were taught was basic wiring ( battery, lamp , wires and switch). So We are not familiar in the project with complex wiring. Any suggestions or detailed scheme would be appreciated.

Absolutely FALSE! The water loses temperature because it is warmer than the surroundings. Heat ALWAYS travels from a point of higher temperature to a point of lower temperature. It can do so in one, or more often, in all of three ways. Convection, conduction and radiation. Only the convection has anything to do with a gaseous intermediary medium.

If your teacher disagrees then he/she needs to do a bit of study of the laws of thermodynamics.
Thank you for the correction. I don't know about thermodynamics yet. I will let our teacher know. Maybe it was my false interpretation.

Wiring thermostat.
You will need a two terminal thermostat. One terminal will connect to LINE Black the other terminal will connect to LOAD Black. It will be a temperature controlled switch for the black wire.
LINE White connects to LOAD White.
GREEN connects to GREEN or to metal frame of heater and/or tank to provide shock protection. This will plug into a GFCI receptacle.
Now I hope a resident ‘Sparky’ will jump in and correct/add to my statements. If they could furnish an easy to understand drawing it would help.
Your basic process is the closed thermostat will supply power to heating apparatus causing it to heat. When the thermostat (in contact with water) reaches cut-off temperature it will open its contacts stopping power to heating apparatus. When water cools to cut-in temperature it will close contacts supplying power to heater. This is an endless cycle repeating as needed.
Have fun!
RR
Thank you for this explanation. If you can help me with a simple diagram it would be very simple for me.

Thank you a lot guys. I will get there.
 
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Old 03-09-14, 12:17 AM
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What about using a fish aquarium heater with built in thermostat?
 
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Old 03-09-14, 06:47 PM
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What about using a fish aquarium heater with built in thermostat?
We thought about this idea but we couldn't find aquarium heater that can reach 50 degree Celsius nor the one that comes with thermostat. If you know any, please share them with me.

Thank you a lot.
 
  #12  
Old 03-09-14, 07:09 PM
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How about a rethink?
Ever hear of an 'Immersion Heater"? Google that and look at the ones for heating a cup of water for coffee or tea. They will boil water in small amount of time.
Found some immersion thermostats, but they are industrial and quite pricey.
Maybe this will jog your thought processes.

RR
 
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Old 03-09-14, 08:12 PM
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  #14  
Old 03-10-14, 02:13 AM
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Red face Age

My son has a similar project for school and he's 13 years old (Biol profile class). Should I allow him to work on his own, or maybe ask someone for supervision? Not sure how dangerous connecting the thermal parts would be. Thanks
 
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