Silent But Deadly: Mike’s Homeowner Guide to Carbon Monoxide Safety with 5-Ton Gas Furnaces

👋 Intro from Mike

Hey there, I’m Mike Sanders. I’ve been around long enough to remember when folks used to run furnaces without detectors, without code compliance, and sometimes—without any clue what carbon monoxide was. 😬

These days, we’ve got better tools, smarter systems, and stronger safety standards, but CO (that’s short for carbon monoxide) is still the most silent danger in HVAC.

If you’ve got one of those big 5-ton R-32 AC and gas furnace combos, you’re probably heating and cooling a good-sized home. That means combustion, ductwork, exhaust vents, and air quality are all on the line—and you better believe CO safety is part of that conversation.

Let’s break down what CO is, why it matters, and how to make sure your HVAC setup doesn’t put your household at risk.

 

💀 What Is Carbon Monoxide and Why Should You Care?

Carbon monoxide is an odorless, colorless gas that comes from incomplete combustion. That means:

• Natural gas doesn’t burn all the way

• Venting isn’t working

• Or the heat exchanger’s cracked

CO binds to your red blood cells faster than oxygen. That means, even in low amounts, it starves your body of oxygen—and that can cause dizziness, confusion, unconsciousness, or worse.

The CDC has a great breakdown on CO poisoning symptoms and emergency responses. If you’ve got gas appliances in your home, especially a high-BTU furnace like the ones in 5-ton systems, you need to know how to protect yourself.

 

🔥 How Gas Furnaces Produce Carbon Monoxide

Your gas furnace burns natural gas (or LP propane) to create heat. That combustion should be complete, meaning the only byproducts are carbon dioxide (CO₂) and water vapor. But when:

• The burner gets dirty

• The flame sensor fails

• The vent is blocked

• Or there’s a crack in the heat exchanger

...incomplete combustion occurs, and CO gets created instead of CO₂.

Even a top-rated model like the Goodman GR9T961005CN, paired with a 5-ton R-32 condenser like the GLXS4BA6010, still depends on a safe venting setup and annual maintenance to stay clean-burning.

 

🏡 CO Danger Zones in 5-Ton Furnace Installations

Larger systems mean larger fuel loads and longer duct runs, which makes safety even more important. Keep an eye on:

1. The Heat Exchanger

The heart of the furnace—where combustion gases transfer heat without mixing with indoor air. Cracks here = big trouble. Use a combustion analyzer or call in a pro annually to check.

2. Exhaust Venting

Venting should be pitched upward, clear of blockages, and made of the right material (usually PVC or stainless steel). Double-check the flue pipes if you’ve ever had work done—bad installs are a common risk.

The NFPA provides guidelines on combustion air and venting safety for fuel-burning appliances.

3. Backdrafting Risks

If you’ve got an oversized kitchen hood, wood-burning stove, or even a too-tight attic seal, negative pressure can pull exhaust gases back into the home. This is known as backdrafting, and it’s a leading cause of indoor CO exposure.

You can use a smoke test (matchstick near the vent hood) to check airflow direction when the furnace runs.

 

📟 CO Detectors: Your First Line of Defense

Here’s the deal: even the best furnace setup can go sideways. That’s why carbon monoxide detectors are mandatory in most building codes—and smart for every home.

Place detectors:

• Near every bedroom

• On every level of the house

• At least 15 feet from the furnace

Consumer Reports has a trusted guide to choosing reliable CO detectors. Brands like Kidde, First Alert, and Nest Protect are highly rated.

Don’t forget: detectors expire after 7–10 years. Check the date on the back and test monthly.

 

🧰 Real-World Installation Tips for CO Safety in 5-Ton Systems

✅ Use a Licensed Installer

I’m all for DIY when it’s safe, but with gas and combustion, it pays to have a pro handle:

• Gas pressure regulation

• Venting calculations

• Furnace startup checks

• CO test with a combustion analyzer

✅ Check for Local Codes

Many areas require:

• Mechanical permits

• Combustion air requirements

• Annual CO inspections (especially for rentals)

Your local building department website can tell you what applies to your county.

✅ Match Furnace Size to Home Load

A 5-ton AC doesn’t automatically mean you need a 100K BTU furnace. Oversized units short-cycle, underheat your home, and run inefficiently—leading to incomplete combustion.

Use loadcalc.net or hire a tech to run a Manual J and S.

 

🛑 Warning Signs of Carbon Monoxide Trouble

Know these red flags. If you see them, shut down the system immediately and call a licensed HVAC pro:

🚩 Furnace flame turns yellow
🚩 Soot or burn marks around the vent
🚩 Rust on the flue pipe or heat exchanger
🚩 Frequent tripped CO alarms
🚩 Condensation inside windows (from excessive combustion moisture)
🚩 Family members feeling dizzy, nauseous, or confused—especially at night

Also, never ignore a chirping detector or one that reads above 35 ppm. That’s the threshold the EPA recognizes as a cause for concern.

 

🧠 Mike’s CO Safety Maintenance Checklist

Here’s a handy homeowner schedule for keeping your 5-ton gas furnace safe:

📅 Every Month:

• Replace your air filter

• Check detector batteries

📅 Every 6 Months:

• Inspect flue pipe for blockages, corrosion, and sagging

• Wipe down burner and blower compartment

📅 Annually:

• Have a licensed tech do a CO test

• Inspect heat exchanger for cracks

• Clean burner jets

• Test draft inducer motor

Pro tip: Ask your tech to document CO ppm readings after the test—that way you’ve got a baseline for future checks.

 

🧩 How R-32 Fits Into This

While R-32 refrigerant doesn’t produce CO (it’s on the AC side), the systems that pair with gas furnaces—like Goodman’s R-32 units—require tight coordination between heating and cooling components. Poor airflow, mismatched ducting, or leaky returns can affect combustion quality.

It’s another reason why sizing and ventilation matter so much, especially in high-output 5-ton configurations. Want to know more about why R-32 is the smarter refrigerant? Check out this overview from Daikin.

 

👋 Wrap Up from Mike

Look, I know CO safety doesn’t sound as exciting as talking about cooling BTUs or shiny smart thermostats, but it’s the foundation of a safe, healthy HVAC system.

You’ve invested in a serious setup—a 5-ton R-32 combo isn’t just powerful, it’s a sign you care about comfort and efficiency. Just don’t let safety be the thing you skimp on.

Install your furnace right, test it yearly, and keep those detectors fresh. Trust me, it’s way cheaper than a trip to the ER.

Got questions? I’m here. Got a system to upgrade? Head over to the 5-ton R-32 collection at The Furnace Outlet. They’ve got solid deals, fast shipping, and none of the big-box confusion.

Want some more electrical tips for your 5-ton R-32 combo? Visit this guide: Is Your Electrical Panel Ready for a 5-Ton R-32 System? Let's Break It Down.

Until next time—keep your air clean, your detector chirping (just once a month, please), and your family safe.
—Mike 👨🔧