The first mystery to me was this Instant Low Wattage button. Basically it just keeps the wattage in low range only no matter what, making the AC cool the room in longer time.
The Low Wattage button of Sharp Inverters is basically a power consumption limiter. There are three settings for the 1.5 Ton Sharp AH-XP18MV:
H --> High (Unlimited)
L1 --> Level1 (Limited to 1 kW power consumption)
L2 --> Level2 (Limited to 0.8 kW power consumption)
The power consumption display on the IDU will change each time this Instant Low Wattage button is pressed. It will blink "H" or "L1" or "L2" for the 1st second, and then blink "1.0" kW for L1 and "0.8" kW for L2 in the 2nd second respectively. It will then continue to display the power consumed by the air conditioner in real time.
The question arises as of why they included this feature and what is the benefit of limiting the power input which will ultimately lead to reduced cooling capacity during initial startup. Its like running a 1.5 Ton Inverter on anemic dose of 1 kW power at L1 where it basically operates at 1.15 Ton. So if one always keeps it at L1 why spend the extra money on a 1.5 Ton and not get a 1.1 Ton Inverter air conditioner which will max out at 1.2 Ton while saving an initial cost of INR 10K. The reason I believe is that a 1.1 Ton Inverter operating at its maximum operating capacity or even rated capacity can never match the cooling efficiency (EER) of a 1.5 Ton Inverter operating at limited power so that it runs like a 1.15 Ton. Let us review the work cycle of an air conditioner in laymans terms to get a full picture.
Air conditioners follow a simple rule where they absorb heat from air situated inside the room in question and reject that heat to the outside atmosphere. For split ACs when the cross-flow fan situated inside IDU starts to rotate it sucks air from above the IDU passing it through the cold evaporator unit situated inside which is finally blown out from below where the louvers are situated to guide the cool airstream. While passing through the evaporators the residence time the air spends causes heat transfer from indoor air to the evaporator via convection. This heat absorbed is then carried by the refrigerant gas via dedicated copper pipes to the ODU situated outdoor and are finally ejected to the outdoor atmosphere via convection. The component that does this very important job is known as the condenser unit or heat exchanger. An outdoor fan is provided to aid the heat exchange by expulsing the air through the condenser fins.
The overall efficiency of an air conditioner is highly dependent on how efficiently these heat exchange of the both indoor and outdoor takes place. A 1.5 Ton Inverter will always have a much bigger evaporator and condenser unit than a 1.1 Ton. So if both are operated at identical tonnage of say 1.1 Ton cooling capacity, the 1.5 Ton will absorb heat much faster (due to bigger evaporator) from indoor and expulse heat to outdoor at a much higher rate (due to bigger condenser). So cooling efficiency aka EER climbs up for the 1.5 Ton Inverter while operating at reduced 1.1 Ton cooling capacity and it consumes less power than a 1.1 Ton Inverter air conditioner operating at its rated capacity.
Also the IDU of a 1.5 Ton Inverter air conditioner have a much bigger skew fan which results in higher indoor airflow leading to a further feeling of cooling in human beings. The Sharp 1.1 Ton Inverter has a max indoor airflow of 10.9 CMM while their 1.5 Ton does a max of 16.8 CMM. With the 1.5 Ton capable to produce 54% more indoor airflow the room cools faster and humidity falls rapidly which produces the rapid sensation of cooling in human beings. And even now if you keep it at a high indoor temperature of 29 C the people inside the room (120 sqft) will feel comfortable due to the high airflow rate. For the same room a 1.1 Ton Inverter AC needs to run at 27 C to produce the same amount of comfort level due to its reduced airflow capacity thus increasing the compressor load thus consuming more power.
So the L1 level is like operating the air conditioner at the desired tonnage or cooling capacity which is going to return better average efficiency wrt normal intended use. An analogy will be driving a car at reduced speeds
[Reduced Cooling Capacity] so that its gives better mileage
[Lower Average Power Consumption] while not being so slow that it takes ages to reach the destination
[Set Temperature]. Of course driving at maximum speeds
[Maximum Cooling Capacity] the person could have reached the destination faster
[Set Temperature] but mileage would have definitely suffered
[Higher Average Power Consumption].
Hope this helps.
