hello all,
First of all thank u, for all ur valuable suggestions its very kind of u all,but u guys are not getting the point that i have already written, i only want two frequencies (one for increment and one for decrement sensing).the suggestions given by u all describe some or the other protocol for e.g RC5 or something like that.

Isin't there any way to just distinguish a UP key pressed is one frequency and DN key pressed is the other frequency.Which would increment or decrement the power delivered to heater.

According to one of my collegues suggestion i could use a simple 555 timer to TX one frequency for UP key and other frequency for DN key.This frequency would be given to INT0 pin, sensing which i could start a timer and the count that would be there for next interrupt would be taken into one register and compared with a pre defined count calibrated for UP or DN key.if the count in register and that timer register TH or TL are equal it would decide which key is pressed if the count is not equal it would decard saying that it was just a transient or noise.

Is this method feasible pls suggest .

Though i have tried to explain all the things i want to pls try to visualise my application and then suggest a solution, its good to know that all u people are great masters in knowing all such technical jargon on IR transmission, but what i feel is considering the simplicity of the application suggest a solution which would be viable and cheap,rather than complex and difficult to implement.

with this i remain thankful to u all and pls suggest a solution as soon as possible.