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230v Thermostat - Electronics wiz help required
ringram:
Heating systems are typically 230V. The actual voltage may vary slightly.
If this is a "HEATING" thermostat, it won't work for cooling the cabinet. If you have it set for 20C, and the ambient temperature is higher, the contact will be open. (because there is no call for heat). If the ambient temperature falls below the set point, the contacts will close (calling for heat).
You want a thermostat for cooling. So, as the cabinet temperature rises, the thermostats contacts will close, which will turn on the fan, and cool the cabinet.
Fozzy The Bear:
--- Quote from: ringram on April 07, 2008, 07:50:48 am ---If this is a "HEATING" thermostat, it won't work for cooling the cabinet. If you have it set for 20C, and the ambient temperature is higher, the contact will be open. (because there is no call for heat). If the ambient temperature falls below the set point, the contacts will close (calling for heat).
--- End quote ---
Easily fixed...... You just put a relay on the output.... So when the contact closes on the thermostat it fires the relay and opens a set of normally closed contacts.....you connect your fan via these NC switched connections on the relay. So that the fan runs until the temperature drops to the level set by the thermostat.
Best Regards,
Julian (Fozzy The Bear)
ex_directory:
--- Quote from: ringram on April 07, 2008, 07:50:48 am ---Heating systems are typically 230V. The actual voltage may vary slightly.
--- End quote ---
Everything in the UK is 230v.
When this was given to me it was already connected up to the fan, suggesting it should work as temp rises otherwise what would the electrician who put it together be using it for (unless it was to suck in warm air !!).
The data sheet at the top also suggests it should work as temp rises so am hoping it is just the dial that is confusing. Time to get the hair dryer out I fear.
ex_directory:
Found a pic of the thermostat.
DaOld Man:
--- Quote ---Let's say the room temp is 20'c, i have the dial set at 60'c (max). At this point the fan is off, when I then turn the dial down, at about 10'c the fan starts. If I turn it back up again it will shut off. So obviously the dial reading 0'c to 60'c is not referring to the room temp?
--- End quote ---
Thats ok. For simplicity's sake, lets say the temp settings on the thermostat dial are between 1 and 10.
On a cooling system, lets say you want the temp to be 5, so you set the thermostat on 5.
If you turn the thermostat down to 2, then you are saying you want the temp now to be 2, so the fan comes on.
When the temp gets down to 2, the fan will cut off.
Now lets say the thermostat is placed on 5 again, and the temp is 6, so the fan is running because the temp is above the setting.
If you turn the thermostat up to 7, the thermostat now wants a temp of 7, so it turns the fan off.
The fan will stay off until the temp reaches 7. Above 7 the fan will come on again.
So you are correct about the dial reading. it is not referring to the actual temp, but what you want the temp to be.
You need a thermometer to tell you the actual temp. Also, the fan will turn on and off at around the setting, it will be a little above the set mark and a little below the set mark. This is where the hysteresis comes in, but I wouldnt worry about that.