Gas Furnace Carbon Monoxide Safety in Monmouth County NJ

A gas furnace puts carbon monoxide into your house when exhaust that should go up the flue ends up in the air you breathe instead. The EPA's list of household carbon monoxide sources covers the ways that happens: leaking chimneys and furnaces, back-drafting from furnaces and gas water heaters, and combustion devices whose flue is improperly sized, blocked, disconnected or leaking. That is three failure points: the heat exchanger, the vent, and the air the burner has to work with. Most homeowners only ever hear about the first one.

The three ways it gets into your air

The heat exchanger is a metal chamber inside the furnace. The burner flame heats it, the air from your ducts flows around the outside of it, and the exhaust stays sealed inside and leaves through the flue. That separation is the entire safety design. A crack or a rust hole lets exhaust cross over into the air going to your bedrooms.

The flue is the pipe or chimney liner that carries exhaust outside. EPA ties flue defects to the appliance itself, listing worn or poorly maintained combustion devices whose flue is improperly sized, blocked, or disconnected and leaking. A neglected furnace and a bad vent usually turn out to be the same story, which is why the vent gets checked on the same visit as the burner rather than on its own.

Combustion air is the third one, and it is the one nobody looks at. A burner needs air to burn cleanly. If the furnace sits in a tight closet or basement room and cannot draw enough, it pulls air down the nearest vent instead. That is back-drafting, and EPA lists it for furnaces, gas water heaters, wood stoves and fireplaces. Share one small room between a furnace and a gas water heater and the furnace can starve the water heater, pushing its exhaust into the basement.

The symptom pattern that separates this from the flu

Carbon monoxide is colorless, odorless and tasteless. You will not smell it. What you can notice is a pattern, and EPA publishes the exact questions an emergency room will ask you:

• Do the symptoms happen only in the house?
• Do they fade or go away when you leave, and come back when you return?
• Is anyone else in the household feeling the same thing?
• Did everyone's symptoms start around the same time?

Headaches, dizziness, confusion, nausea and shortness of breath are all on EPA's list. So is the giveaway: flu-like symptoms that clear up after you leave home. If you are answering yes to those questions, EPA's instruction is to get fresh air immediately, open doors and windows, turn the fuel-burning appliances off and leave the house. Its other instruction is to not ignore symptoms, particularly if more than one person is feeling them.

What a normal reading actually is

This is the part almost nobody gives you a number for. EPA puts average carbon monoxide levels in homes without gas stoves at 0.5 to 5 parts per million. Near a properly adjusted gas stove, 5 to 15 ppm is common. Near a poorly adjusted one, 30 ppm or higher.

So the ordinary scale is single digits. A steady reading well above that in a room with a gas appliance is worth a phone call. Be careful with bigger numbers you find online: the 50 ppm figure on EPA's page is an OSHA occupational limit for workers across an 8 hour shift, not a target for a house.

On alarms, EPA is more cautious than most contractors are. It calls a detector a backup and not a replacement for keeping the appliance in good shape, and notes that in lab testing some units failed to alarm even at very high levels. Buy UL certified and follow the manufacturer's placement instructions.

Six things you can check yourself this week

None of these need tools, and none of them require opening the furnace cabinet.

• Watch the flame for a full minute. Through the sight glass, a healthy gas flame is mostly blue, maybe with a small yellow tip, and it holds steady. Mostly yellow, lazy, or rolling out toward you is a call, not a wait-and-see.
• Look for black. Soot streaks or scorching at the flue collar, at the cabinet seams, or where the pipe enters the chimney. A flue scorched visibly black is a sign it may not be drafting right, and that is a fire risk sitting on top of a carbon monoxide one.
• Follow the flue with your eyes, joint by joint. Count the joints between the furnace and the chimney. Every one should be tight and pinned, the pipe should run uphill toward the vent with no sags, and there should be no rust holes and no foil tape doing a structural job.
• Count what shares the vent. A furnace and a gas water heater often tie into one chimney. Note whether they are in the same small room, and whether that room has a louvered door or an air opening into the rest of the basement.
• Check the outside end. Find where the flue or the white high-efficiency PVC pipes exit the house. They need to be clear of leaves, nests, dryer lint and snow.
• Read the instructions that came with your alarms. EPA's advice on carbon monoxide detectors is to follow the manufacturer's instructions for placement, use and maintenance. Replacement timing is part of that, so check the back of each alarm for a date and check what the instructions say about it.

Why the vent is the weak link in older Freehold homes

About 77 percent of households in the 07728 ZIP heat with natural gas, so this is the common setup here, not a rare one. What varies is the age of whatever the furnace is vented into.

In Freehold Borough, more than 40 percent of homes were built between 1940 and 1969 and roughly 30 percent before 1939. The oldest of those were built for hydronic or steam heat, a boiler with radiators, originally burning coal or oil, and many were converted to natural gas later. A masonry chimney built for a coal boiler is not automatically the right size for what got installed decades afterward, and EPA names an improperly sized flue as a carbon monoxide source in its own right.

In Freehold Township, the 1960s developments such as Stonehurst and Monmouth Heights are ranches, raised ranches and split-levels, mostly with basements. That is where the equipment usually lives, so that is where to look. If your furnace and your water heater share that room, you have the shared-air setup described above, and the question becomes whether the room has a real combustion air opening. Basements matter twice over here: Monmouth County is EPA Radon Zone 1, so basement air sealing and combustion air have to be planned together.

Freehold sits in climate zone 4A with a winter design temperature of roughly 13 degrees. That is the cold your heating system is sized against, so the venting needs to be right before the season starts, not during it.

What a real combustion check measures

How often to have this done is its own question, and our guide on how often a furnace needs service answers it. EPA's version is short: have fuel-burning appliances inspected by a trained professional at the beginning of every heating season, and make sure the flues and chimneys are connected, in good condition and not blocked.

What matters just as much is that the visit produces numbers. A combustion analyzer in the flue reads carbon monoxide in the exhaust in parts per million. A draft reading confirms the exhaust is going up and out. Gas pressure gets measured at the manifold instead of guessed at. The heat exchanger gets inspected for cracks and corrosion, which is a different job from glancing at it. A spillage check at the water heater shows whether the two appliances are fighting for air. Ask for those readings. A heating system check-up that hands you numbers you can compare next year is worth more than one that ends with the word fine.

On a job in Freehold, the furnace had been installed right next to the water heater and was pulling air from around it, which raised the risk of back-drafting the water heater. A blower door test on that house read about 3,100 CFM50 on roughly 2,600 square feet, which is not ideal but nowhere near as leaky as some houses we test.

New equipment is not automatically safe equipment either. On a new-construction job in Millburn, we were brought in for an independent check before the walls closed in. Both furnaces were sealed-combustion units that require a dedicated fresh air intake, and neither one had it installed. The installing contractor's answer was that they do it that way all the time.

When to call, and when to just leave

If an alarm sounds and anyone has symptoms, get everyone out of the house immediately and seek medical attention. EPA's wording is to go to an emergency room and tell the physician you suspect carbon monoxide poisoning, which a blood test done soon after exposure can often confirm. If nobody has symptoms, EPA's order is: ventilate with fresh air, shut off the furnace, water heater, range and anything else burning fuel, and have a qualified technician check the appliances and chimneys before anything goes back on.

Short of an alarm, soot, a rolling yellow flame, a rusted or separated flue joint, or that come-and-go headache pattern each earn a same-week visit, and furnace repair is where that starts. A cracked heat exchanger is one of the few furnace problems that usually ends in replacement rather than repair, and our guide on whether an old furnace can be repaired walks through how that call gets made.

FAQ

Can a gas furnace leak carbon monoxide without any smell?
Yes. EPA describes carbon monoxide as odorless, colorless and toxic, and warns that because you cannot see, taste or smell it, it can affect you before you know it is there. Smell is not a warning system.

How do I tell carbon monoxide from a winter bug?
Go by the pattern, not the symptom. EPA's test is whether the symptoms happen only at home, fade when you leave and return when you come back, and whether more than one person in the house has them at the same time.

Does a cracked heat exchanger always mean a new furnace?
Usually. The part sits deep in the cabinet, and on an older unit the labor to reach it rarely makes sense against the cost of replacing the furnace. Either way, confirm the crack with a camera and combustion readings first.

If it has been more than a heating season since anyone put a combustion analyzer on your furnace, or an alarm went off and you never got a real answer why, get in touch and we will come test it. Call (848) 288-1133 and we will get you on the schedule.