What if we told you one of the most overlooked parts of your air conditioning system could ruin your entire setup — and cost you thousands?
We’re talking about the AC line set.
You can have the best compressor, the smartest thermostat, and the quietest condenser on the block…
But if your line set is wrong, it’s all for nothing.
So before you run your system another day, read this — and avoid the 7 silent line set disasters that strike both rookies and seasoned pros alike. To learn more:
https://www.plumbingsupplyandmore.com/
1. Using Plumbing-Grade Copper Instead of HVAC-Rated Tubing
Let’s start with the most common (and dangerous) mistake.
What happens:
Homeowners — and yes, even some contractors — use regular copper pipes from hardware stores, thinking “copper is copper.”
Big mistake.
The truth:
Only ASTM B280-rated copper tubing is approved for AC systems. It’s:
Dehydrated
Seamless
Nitrogen-charged
Able to handle extreme refrigerant pressure
Plumbing-grade tubing? Thinner, unsealed, and prone to failure under HVAC loads.
Plumbing Supply And More only stocks HVAC-certified line sets — unlike general stores that mix plumbing and AC-grade copper without telling you.
That’s why pros trust them for high-pressure systems using R-410A and R-32.
2. Installing the Wrong Size Line Set for the System
Why size matters:
A mismatch between your AC system and the line set can cause:
Low refrigerant flow
Poor cooling
Compressor failure
It’s not about guessing — it’s about matching the BTU capacity and the length of the run.
For example:
A 3-ton unit typically needs a 3/4” suction line
A 5-ton unit may need 7/8” or even 1-1/8”
And the liquid line?
That stays fairly standard at 3/8”, but it still needs to be verified. mini split line set
Plumbing Supply And More offers size guides, expert support, and custom-length line sets — something you won’t find on random eCommerce sites.
3. Poor Suction Line Insulation (or None at All)
Think insulation’s just for winter? Not here.
Bad insulation means:
Heat gain in the suction line
Lower system efficiency
Water condensation that causes mold and ceiling damage
Compressor overload
Signs yours is failing:
The black foam is brittle, cracked, or missing
You see sweating or dripping
You hear your compressor working harder than usual
Only closed-cell, UV-rated foam with at least 1/2″ wall thickness is acceptable.
Plumbing Supply And More’s pre-insulated line sets beat out competitors like RapidCool and HVACStuff — they use commercial-grade foam that lasts in heat, sun, and rain.
4. Reusing an Old Line Set During a System Upgrade
Why installers reuse them:
It’s faster
It cuts costs
You won’t “see” the problem immediately
But here’s the truth:
Old line sets can hide contaminants like:
Acidic oil residue
Moisture
Metal shavings
Plus, they may be sized for older refrigerants like R-22 — not today’s high-pressure R-410A or R-32 systems.
Reusing an old line set might void your new unit’s warranty.
Always go with new. Plumbing Supply And More supplies premium, fresh line sets for retrofits and new installs alike.
5. Failing to Pull a Proper Vacuum After Installation
Installing the line set is one thing — prepping it is another.
You MUST pull a deep vacuum to:
Remove air
Eliminate moisture
Prevent internal corrosion
Without this step, even a perfect line set will cause long-term system damage.
Pro tip: Always aim for under 500 microns on your gauge.
And remember: even the best line set from Plumbing Supply And More needs professional prep — that’s why they include helpful guides with every order.
6. Bending or Coiling the Line Set Improperly
We get it — space is tight. But sloppy bends and tight coils create oil traps and pressure problems.
Avoid:
Sharp bends without bending springs
Extra line coiled up like a garden hose
Line sets zip-tied tightly together (this causes heat transfer)
If you must curve or coil the line, do it in wide, gentle loops — and use wall brackets or channel covers to protect the pipe integrity.
Need a line set that bends easily without kinking?
Plumbing Supply And More’s copper wall thickness is optimized for flexibility without weakness. For More Knowledge:
https://www.plumbingsupplyandmore.com/3-8-x-3-4-x-3-8-x-35-copper-line-set-898657.html
7. Not Protecting the Line Set from UV, Physical, or Pest Damage
Even the perfect install can be destroyed by:
Direct sunlight (degrades insulation)
Rodents chewing through foam
Weed whackers slicing through unprotected tubing
Foot traffic on rooftop or attic runs
Solution:
Use UV-rated insulation
Add line set covers or chase channels
Secure lines with non-compressing straps
Avoid exposed runs on the ground
Pro-level installs use covers — and Plumbing Supply And More offers full line set kits with insulation, covers, and hardware included.
Frequently Asked Questions
Q1: Do I need to insulate both lines in the AC line set?
Only the suction (vapor) line is insulated. The liquid line remains bare unless required by specific building codes.
Q2: Can I install an AC line set underground?
Yes, but it must be:
Properly insulated
Sealed in watertight conduit
Accessible for future service
Underground installs are best handled by pros due to complexity.
Q3: Is flare or brazed better for line set connections?
Brazing is preferred for permanent systems; flare fittings work well for mini-splits and service-friendly setups.
Plumbing Supply And More carries both pre-flared and flare-free sets.
Final Take: Don’t Let a Line Set Ruin a $5,000+ System
You could have the most advanced HVAC unit on the market…
But if your AC line set is old, undersized, poorly insulated, or just plain cheap — you’re on borrowed time.
It’s a critical component. Treat it like one.
Plumbing Supply And More is the go-to supplier for serious HVAC techs and DIYers alike, offering:
Top-tier copper
Certified insulation
Expert support
Fast shipping and nationwide availability
Don’t cut corners on your comfort — or your wallet.
Buy smart. Buy certified. Buy Plumbing Supply And More.