When sub-zero weather is encountered, what limits the efficiency of a runaround heat recovery system?
a) higher viscosity of the fluid increases pump power demand
b) the temperature differential between inlet and exhaust isn't sufficient
c) fluid flow through the coils must be throttled during cold weather therefore heat recovery is minimal
d) in sub-zero temperatures, heat is not recoverable
e) frost build-up on the recovery coil restricts airflow over the coil
Answer: E