Tsup and Tz are temperature in C. I think you are confusing these 2 equations:

Q = Mdot * Cp * (Tsup - Tz)

and

Tz), and
Q = Mdot * (Hsup - Hz)

Tsup and Tz are temperature in C. I think you are confusing these 2 equations:

Q = Mdot * Cp * (Tsup - Tz), and
Q = - Mdot * (Hsup - Hz)

Tsup and Tz are temperature in C. I think you are confusing these 2 equations:

Q = Mdot * Cp * (Tsup - Tz), and
Q - Mdot * (Hsup - Hz)