Thread: Air Conditioning

I'm sorry but your version of the drop in current flow to you AC doesn't follow the rules of physics.

The AC is powered by a compressor which runs at a relatively constant load and therefore fixed current. The coolling is achieved by dumping the heat in the gas at the exchanger and cleaning it will not reduce the current but it will reduce the length of time that it runs for to achieve the desired temperature drop. This will save you money with a shorter duty cycle.

Cleaning the heat exchanger will in fact increase the air flow and that will increase the current draw but this will result in faster cooling.

Your conclusion that cleaning the heat exchanger will save you money is correct albeit for the wrong reason.

The cause of the current drop in the wiring is a mystery but it is definitely not due to cleaning the coil.

Originally Posted by Bohdan

I'm sorry but your version of the drop in current flow to you AC doesn't follow the rules of physics.

Unless it is one of the inverter systems where the motor runs more or less constantly but with varied speed...

Originally Posted by Bohdan

I'm sorry but your version of the drop in current flow to you AC doesn't follow the rules of physics.

The AC is powered by a compressor which runs at a relatively constant load and therefore fixed current. The coolling is achieved by dumping the heat in the gas at the exchanger and cleaning it will not reduce the current but it will reduce the length of time that it runs for to achieve the desired temperature drop. This will save you money with a shorter duty cycle.

Cleaning the heat exchanger will in fact increase the air flow and that will increase the current draw but this will result in faster cooling.

Your conclusion that cleaning the heat exchanger will save you money is correct albeit for the wrong reason.

The cause of the current drop in the wiring is a mystery but it is definitely not due to cleaning the coil.

I'm sure you're correct. I can only report what I saw.

My theory is that by more efficiently removing the heat. the compressor was reducing less gas to a liquid state.

I guess we file this one under another great mystery of life.

Originally Posted by Bohdan

I'm sorry but your version of the drop in current flow to you AC doesn't follow the rules of physics.

The AC is powered by a compressor which runs at a relatively constant load and therefore fixed current. The coolling is achieved by dumping the heat in the gas at the exchanger and cleaning it will not reduce the current but it will reduce the length of time that it runs for to achieve the desired temperature drop. This will save you money with a shorter duty cycle.

Cleaning the heat exchanger will in fact increase the air flow and that will increase the current draw but this will result in faster cooling.

Your conclusion that cleaning the heat exchanger will save you money is correct albeit for the wrong reason.

The cause of the current drop in the wiring is a mystery but it is definitely not due to cleaning the coil.

I dont think this is quite right, but I will fess up here and say that I am falling back on common core engineering stuff from uni.

A dirty condenser means a higher temp difference. higher temp difference means increase gas pressure, increase pressure means motor works harder.

Might I also add, I though this is why aircon compressors are always supposed to be located where they get good airflow as it increases efficiency.

Originally Posted by Bohdan

I'm sorry but your version of the drop in current flow to you AC doesn't follow the rules of physics.

The AC is powered by a compressor which runs at a relatively constant load and therefore fixed current.

Sorry Bohdan; but your source of information regarding how compression refrigeration systems operate is incorrect. The motor load is governed by the gas pressure required to condense the gas into a liquid, this pressure is directly related to the temperature of the cooling medium across the condenser and its efficiency. From memory the standard designed temperature differential for a fan cooled condenser is about 14 degrees K, if it is dirty that differential effectively rises meaning that the gas pressure has to rise higher to reach the vapour condensing point. Obviously this load will also increase as the ambient air temperature rises.

Having a clean condenser reduces the running load of the motor by lowering the compressor discharge pressure, additionally the whole process becomes more efficient as the liquid refrigerant is now at a lower temperature before it enters the expansion phase in the evaporator.

Rrich's advice and the reasoning behind it is sound; one addition I would add is to use a PH-neutral surfactant coil cleaner. This is available from most engineering suppliers such as Blackwoods, or dedicated refrigeration suppliers like Actrol.

Lastly; this also applies to refrigerators. The older style convection coils at the back need to be kept clean and have adequate airflow, more modern fridges use fans but again the air intakes must be kept clean.

I've been told by a friend who teaches AC that cleaning the coils with water is something that should be done regularly. The other day the cat got a bird and some of the down ended up in our mini-split coils.