I am from Wuqing, Tianjin. I didn't receive a notice to pay the heating bill last year, but now I have received a letter from a lawyer to pay the bill. Is this reasonable?

It depends on whether the heating stop agreement you signed clearly stipulates the heating stop period. If the period of stopping heating is not clear, it will be regarded as stopping heating until you reapply for heating. In this case, it is your own fault that the heating company heats your home without your application, so you don't have to pay the heating fee. To answer your question, I just registered, hehe.