Can I Install Salvaged Ductwork in My House?

LESLIE: Mary in Missouri, you’ve got The Money Pit. How can we help you today?

MARY: My husband and I are trying to install central air in our home. It’s a ranch-style and we bought the central-air unit and the ductwork from a building that had been torn down. And I wondered if we could simply attach the ductwork – and when we’ve cut the holes in the wall and the ceiling for the vents, I wondered if we could just go ahead and attach the ductwork that was there from the previous building or if we had to redo all the ductwork – I mean all the vent piping.

TOM: I guess the answer is maybe. And the reason is because the duct design is going to be dependent on the building. And it depends on the size of the building and the distance that the air has to travel. And if it’s not done right, what will happen is you’ll either create a situation where you have either too much or too little heating or cooling. And most likely, you’ll have too little. And if that happens, you end up wasting, actually, a lot of energy, because the system has to run a lot more to try to make the building comfortable.

So, I would suggest to you that in so far as the duct design is concerned, you really need to have somebody that is experienced in designing these systems lay it out for you. It’s definitely not a do-it-yourself project; it’s not the kind of thing that you can tackle, even if you’re very industrious first time out, because you might get it wrong.

It depends a lot on the size of your building, how many windows are in your building, where the building faces. There’s a heat-loss calculation that’s done and then based on that, you determine how much warm or cold air you have to get to each room. So you can’t necessarily sort of just completely copy what was done in an older house unless it happens to be an identical house.

So this is a point where it’s good that you got the equipment inexpensively, you got the ductwork inexpensively. You do need to spend a little bit of money on getting it laid out properly, Mary, or you just won’t be comfortable. Does that make sense?

MARY: Yeah, that was what I wanted to check, because we’re pretty self-sufficient but I had a feeling this might be more than we could tackle.