thermostat w/ DC output

[markietan]

i wanna make a thermostat w/ DC output such that the output will be around 7 - 12V depending on the temperature of the water

how do I go about doing that?

reason being my chiller is using lots of electricity and i want to add fan to help the cooling process. am thinking of mounting 2 or 3 12mm computer DC axial fan on pvc pipes across the top of the tank

i currently have a thermostat but it outputs AC for my chiller. ideally i would like a separate thermostat to vary the DC fan speed....

if anyone has done this before, can tell me how much such a thermostat will cost? i'm only a poor student.....

thanks for reading

[BarraCudaTM]

i wanna make a thermostat w/ DC output such that the output will be around 7 - 12V depending on the temperature of the water

how do I go about doing that?

reason being my chiller is using lots of electricity and i want to add fan to help the cooling process. am thinking of mounting 2 or 3 12mm computer DC axial fan on pvc pipes across the top of the tank

i currently have a thermostat but it outputs AC for my chiller. ideally i would like a separate thermostat to vary the DC fan speed....

if anyone has done this before, can tell me how much such a thermostat will cost? i'm only a poor student.....

thanks for reading

You can use a thermistor which is a special type of resistor what will change its resistance depending on temperature, you can use NTC or PTC. However, the most practical method is to connect 240V fans to the thermostat output.

[nchin]

What about using a transformer to convert AC to DC?

Like this: -

Thermostat --> AC --> DC

[markietan]

What about using a transformer to convert AC to DC?

Like this: -

Thermostat --> AC --> DC

hi thanks for replying.

mm... in that way i cannot vary the DC voltage, thus varying the fan speed...

i believe the temp controller for my chiller now is doing "Thermostat -> AC" now

actually i found a DC fan that has a variable output built in...

http://www.marinedepot.com/ps_ViewItem.aspx?idproduct=IC5113

but why so expensive one.... haha

[sotongnabe]

Hi Bro

My 2 cents.

It is the easiest to control AC then DC. Furthermore you want to control the voltage, the thermostat can cost a bomb.

If you control AC FAN, then it should be either ON or OFF. Easy....

[nchin]

hi thanks for replying.

mm... in that way i cannot vary the DC voltage, thus varying the fan speed...

i believe the temp controller for my chiller now is doing "Thermostat -> AC" now

actually i found a DC fan that has a variable output built in...

http://www.marinedepot.com/ps_ViewItem.aspx?idproduct=IC5113

but why so expensive one.... haha

What happens if these small computer fans, which are supposed to help the chiller, are not powerful enough? Are you going to add BIG fan to help the smaller fans? No offence

Your original idea is to save electricity, think of options other than adding few more fans. Example, by reducing the number of chiller "start-stop" cycle.s How often does your chiller kick in? The more frequent it is, the more electricity consumption. Also, how long the chiller takes during the kick-in phase, the longer it takes the more electricity. Is the chiller air-filter blocked? etc, etc...