Andrew Leigh
19-10-2009, 09:29 PM
Hi all, my first post.
Have been doing lots of work on my caravan fridge. Have got the venting right, added a thermally controlled fan and finally a close tolerance electronic thermostat.
I know find out that the thermostat is not working out the way I thought it would. It would appear as if the heating and cooling cycle of the absorbtion fridge is such that once the element is switched on it takes a time for the ammonia to heat and therefore there is a rise in fridge temperature whilst this is happening. This is creating fluctuations that make the fridge less accurate than what I would like.
There appear to the novice a couple of ways around this;
1.) I thought of having a permanent heat source keeping the ammonia safely below boiling point. This will be done through PWM control keeping the voltage lower than full mains. Then having the thermostat kick in to do the top up buy applying full voltage to the element. This should greatly reduce the response time.
2.) As the controller is 100 times more accurate and better able to control was to increase the heater wattage.
Is this possible, is it dangerous, am i barking up the wrong tree?
Cheers
Andrew
Have been doing lots of work on my caravan fridge. Have got the venting right, added a thermally controlled fan and finally a close tolerance electronic thermostat.
I know find out that the thermostat is not working out the way I thought it would. It would appear as if the heating and cooling cycle of the absorbtion fridge is such that once the element is switched on it takes a time for the ammonia to heat and therefore there is a rise in fridge temperature whilst this is happening. This is creating fluctuations that make the fridge less accurate than what I would like.
There appear to the novice a couple of ways around this;
1.) I thought of having a permanent heat source keeping the ammonia safely below boiling point. This will be done through PWM control keeping the voltage lower than full mains. Then having the thermostat kick in to do the top up buy applying full voltage to the element. This should greatly reduce the response time.
2.) As the controller is 100 times more accurate and better able to control was to increase the heater wattage.
Is this possible, is it dangerous, am i barking up the wrong tree?
Cheers
Andrew