What is the average cost to replace old flex duct work in a house with a total of 8 vents with new flex. Our son-in-law does A/C work and did it for nothing but we want to pay him a fair price since he won't tell us. So what would be a fair price on this type of work.
Thank you.

What is the average cost to replace old flex duct work in a house with a total of 8 vents with new flex. Our son-in-law does A/C work and did it for nothing but we want to pay him a fair price since he won't tell us. So what would be a fair price on this type of work.
Thank you.

1,500 to 2000 including material