Tinner's Toolbox

  • How to Read HVAC Drawings on a Commercial Jobsite

    When I was installing, I thought we should get priority. Our duct was big, it was rigid, and everybody else’s pipe could bend around it. That was my honest opinion for years. Now I sit on the other side of the table. I work for a general contractor and I read the same drawings from…

  • Shop Drawings vs Construction Drawings, and Which One Wins

    A shop drawing came back with a stamp on it. The field does not match. Somebody is about to eat the cost of that and it is worth knowing in advance who. These are two different documents doing two different jobs, and mixing them up is one of the more expensive mistakes available to a…

  • How to Read HVAC Duct Plans from Mechanical Drawings

    A first year hands you a plan sheet and asks where the duct is. It is a fair question. The sheet is covered in lines, and most of them are not yours. This is how to find your work on a mechanical plan, follow it from the equipment to the last register, and read what…

  • Hanging Duct From Steel Joists: Through, Under and Around

    Hanging duct from steel joists starts with a rule that decides everything after it. You do not cut the joist. Not the chords, not the web, not a little bit off the corner to make a piece fit. The joist is fixed. The duct is the thing that changes. Once you accept that, the whole…

  • Hanging Duct in Floor Joists: Trunk, Take-Offs and Round

    Hanging HVAC duct in floor joists is most of what a basement job is. The trunk goes up under the joists, the take-offs come off the top of it into the bays, and the round pipe runs to the boots. Any work in the basement has one goal — leave as much headroom as possible.…

  • The Drawings Behind Your Ductwork, and Who Owns Them When They Are Wrong

    An install team is an install team. They are trained to install duct, hang it straight, read the drawings and hit the connection points the drawings call for. They have no responsibility to design anything. Which raises the question nobody answers: when the duct will not fit the space, or the air does not come…

  • Duct Hanger Strap: What Gauge, How to Bend It, and How Many Screws

    The spacing question gets all the attention. How far apart do the hangers go is what everybody asks and what everybody writes about. Almost nobody answers the other half: what is the strap itself. What gauge, how long you cut it, how you get a bend in it standing on a ladder, and how many…

  • How to Hang Round Duct With Strap: Wrap, Pinch, Screw

    Rectangular duct sits on a strap. Round duct gets wrapped by one. That one difference changes everything downstream — how long you cut the strap, where the hang point has to land, how many screws go in, and what you do when the run comes out crooked. This is the hands on part. For how…

  • Hanging Duct By Yourself: What Holds It Up

    I will answer the question, and then I will tell you what I actually think. You can hang duct by yourself. I have done it. For small duct, take-offs and short branch runs it is often easier alone than with somebody standing there waiting on you. But I do not recommend it, and the reason…

  • Drives Won’t Go On? The Duct Was Cut Out of Square

    Why won’t the drives go on? Because the flat sheet was cut out of square before it was ever bent. The joint is tight on one side and open on the other, so the drive cannot span the wide side. It is a shop problem that you are finding in the field, and it started…