HVAC Tools and Techniques Notes
Oxy-Acetylene Gear and On-Van Essentials
Carrying case on the oxy-acetylene rig and future coverage: soldering and brazing will be covered next; an oxy-acetylene rig is kept for demonstrations.
Small air conditioning set (MC bottle): the oxygen bottle is called a 20 because it holds 20 cubic feet of oxygen; MC bottle refers to a compact cylinder used in field setups.
Typical usage: a small van setup with compact bottles and multiple small containers inside for field work.
Inspection and documentation tools for field work
Essential field tool: inspection mirror for accessing tight spaces and reading model/serial numbers.
In the past, flashlights and inspection mirrors were used to read model/serial numbers; current best practice is to photograph nameplates with a phone to present parts users with accurate unit identification.
Action item: take pictures of nameplates for parts lookup and service records.
Tubing cutters and IMPS set
IMPS is a small tubing cutter set sold as a compact kit for on-site use.
IMPS vs larger sets: IMPS provides small wheels best for copper tubing; larger wheels exist for steel copper; some wheels are designed for copper, some for steel.
Common usage: most cutters are copper-focused; you can get cut pieces in tight spaces without a big handle protruding and hitting obstacles.
Brand recommendations: Rigid is often cited as a top name brand for plumbing tools; this is highly regarded in HVAC/plumbing tasks.
Cutter sizes: multiple sizes exist, commonly around 3 inches to 5 inches; expect at least two sets (a small set like IMPS and a regular service set).
Flare block and yoke (assembly overview)
Flare block and yoke come as two pieces that work together to form a 45° flare.
Historical context: flares were widely used in the 1950s–1980s in refrigeration; later years saw less flare usage, but mini-splits have renewed the need for flare connections.
This assembly is essential for copper flare connections; the flare block has a 45° bevel on one side and a single half-inch (the backside) flare point.
The half-inch copper flare is paired with the different-sized hole on the flare block; the arrangement allows the yoke to lock and rotate.
Visual detail: one side of the block has the 45° bevel; the backside side handles the half-inch flare.
Quality note: the bevel quality matters; a good bezel is preferred over a rolled edge which doesn’t produce a good flare.
The reason for the half-inch on one side: the yoke must rotate and lock in place; if all flares were on the same side, rotation/locking would be hindered.
Flare preparation and material handling
Material: soft drawn copper is common; bending it can cause splits if rushed.
Height rule of thumb for copper in flare block: between the thickness of a nickel and a quarter; roughly about .
For larger copper pieces (e.g., half-inch, three-quarter inch), the required nickel height is larger, closer to a quarter inch.
Practice note: tighten the yoke handle (using the wing nut) to lock the copper in place during flare forming.
Deburring and prep: check that the copper is properly prepared; if not, lips may form which can cause leaks; deburr and file to remove sharp edges.
Quick test of a flare: run your fingernail along the inside of the flare to feel for a lip; a smooth surface indicates a proper flare. If a lip is present, the flare would leak.
Tooling talk: some students may rely on pocket knives to clean up minor burrs after forming; deburring tools and files offer a more controlled finish.
Practical flare-making tips and cautions
Be mindful of over-tightening during flare formation; back off slightly, then tighten a bit more until it bottoms out.
If the flare lip forms, you must remove the flare and redo it with proper prep.
If you forget to place the flare nut before forming the flare, you must cut the flare off and start over with the flare nut installed.
Be aware of different flare styles (not all are 45° in all automotive contexts) and the need to identify which type is appropriate for the system.
Automotive and HVAC distinctions: automotive swaging (swedging) tools extend metal to match a female fitting; there are many swedge tools with different designs; avoid low-quality multi-tools that resemble a Christmas tree in appearance.
Swaged joints and bezel quality: ensure the tool creates a clean deformation and not a rolled edge; a well-made flare is critical for leak-free joints.
Tubing and piping: copper, aluminum, and plastics
Copper tubing usage: soft drawn copper is increasingly common, but it’s pricier; copper is easy to bend, flare, and cut with appropriate tools.
OD vs ID: all refrigeration piping uses outside diameter (OD) measurements; plumbers often refer to copper by ID; HVAC typically uses OD naming (e.g., 7/8 inch copper is often called 7/8 in OD but plumbers might say 3/4 in ID).
Common sizes: three-eighths inch copper is typically the liquid line; larger sizes exist for gas, refrigerant lines, and service connections.
Hard drawn copper vs soft drawn copper: hard drawn copper is less bendable; it is treated via annealing after extrusion and cooling to restore some ductility; rolled or quenched copper with varnish/wood finish can reduce lifetime due to heat expansion.
Ends and nitrogen: hard drawn copper sticks often arrive sealed at ends with caps and nitrogen to prevent moisture ingress; ends should be capped to prevent moisture absorption.
Moisture and moisture-related issues: moisture in copper piping leads to acid formation (e.g., hydrochloric and hydrofluoric acids) over time; moisture is a key contributor to compressor failures via corrosion and debris.
Storage note: moisture-sensitive ends must be capped when stored, particularly on 50 ft rolls; keep ends capped to prevent moisture ingress; moisture uptake is hygroscopic behavior of parcel contents.
Plumbing copper vs HVAC copper: plumbers’ copper is generally not nitrogen-dehydrated and not intended for HVAC systems; HVAC copper is often sold as soft drawn, nitrogen-filled, and dehydrated for refrigeration use.
Market context: soft drawn copper rolls can be 50 ft long; seven-eighths copper is particularly expensive (price up to around $$700 per 50 ft roll) in recent times; 50 ft rolls come with ends capped and nitrogen filled to maintain dryness; some rolls also come in shorter lengths (25 ft) to reflect price changes.
OD vs ID in polyethylene and other piping: newer HVAC and geothermal uses polyethylene (PE) piping, particularly for loops and ground exchanges; polyethylene piping is often used with glycol and requires different joining methods (heat fusion, etc.).
Polyethylene in geothermal: PE piping is used for geothermal loops (e.g., 600 ft down and back up) and glassing the system with glycol;