Smell gas or feel ill? Leave first
If you smell gas, or anyone in the house has a headache, nausea or dizziness near the heater, do not troubleshoot. Get everyone out, pets included, and do it before you read another line. We dispatch 24/7, but the order below matters more than any phone call to us.
- Leave the building right away and do not flip light switches, use a lighter or unplug anything on the way out.
- From a safe distance outside, call 911.
- Next, call PG&E and report the smell or the suspected leak.
- Only after the fire department and the gas utility have cleared the house, call a licensed plumber to find the cause.
Do not go back in to shut off the gas yourself. If the gas gets shut off, PG&E has to be called to turn it back on.
What an exhaust leak actually is
A gas storage heater burns gas in a chamber under the tank. The hot combustion gases rise through a center flue tube, into a draft hood on top, and then up a vent pipe that carries them outdoors. An exhaust leak is any break in that path, or any condition that makes the gases come back down into the room. This is called backdrafting.
Do not confuse it with a gas leak. A gas leak is unburned fuel escaping from a pipe, valve or fitting, and it smells like rotten eggs. Exhaust is burned gas, and the carbon monoxide in it has no smell at all. That is why the physical signs on the heater matter.
Flue looks wrong or the draft hood is hot? Call (855) 575-2890 from outside the house and ask for a licensed plumber to inspect the heater.
Call (855) 575-2890Physical signs of a leaking flue
You can look for most of these from a safe, ventilated distance with the heater running normally. Do not touch hot metal.
Warning signs at the heater
- Black soot streaks or staining on the draft hood, the top of the tank or the wall behind it.
- Rust flakes or white mineral crust around the vent pipe joints, which means moisture is condensing in the flue.
- A draft hood that is hot to the hand within a few minutes of the burner starting, when it should stay only warm.
- Scorch marks or melted paint above the burner access panel at the bottom of the tank.
- A yellow, floppy or lazy burner flame instead of a steady blue one with small points.
- Vent pipe sections that have sagged, separated at a seam or lost their sheet metal screws.
- Persistent condensation or a stuffy, burnt smell in the closet or garage where the heater sits.
Why the exhaust ends up in the room
Most backdrafts come from one of a few causes. The vent pipe may have slipped apart after years of heating and cooling. The vent may run too flat, since exhaust needs a steady upward pitch to rise. A bird nest or rust scale can partly block the vent where it exits the roof.
Air supply is the other common culprit. A heater in a closed closet or a tight laundry room may not get enough combustion air. A strong bathroom fan or a dryer in the same space can pull exhaust back down the flue.
Smell, symptom or stain: how urgent is it?
Use this as a quick sort. When two or more rows apply to you, treat it as the more serious row.
| What you notice | What it likely means | What to do |
|---|---|---|
| Rotten egg smell anywhere near the heater | Fuel leak at a pipe, valve or burner | Leave, call 911, then PG&E, then a plumber |
| Headache or nausea while the heater runs | Possible carbon monoxide from backdrafting | Get outside into fresh air and call 911 |
| Soot streaks on the hood or tank top | Exhaust spilling out at the draft hood | Turn the heater to pilot or off, call a plumber |
| Rust or water stains on vent joints | Condensation in a cool or undersized vent | Schedule a vent inspection within days |
| Loose or sagging vent pipe | Joint separated, exhaust leaking at seam | Do not run the heater until it is reconnected |
A carbon monoxide alarm is a backup, not a diagnosis. Test the batteries and replace any alarm that is past the date printed on its back.
How a plumber tests for backdrafting
A licensed plumber will start by looking at the vent path, the draft hood and the burner. A draft test measures whether exhaust is actually rising. Many pros watch a match, a mirror or a small smoke pencil near the draft hood opening while the burner runs. A combustion analyzer reads the carbon monoxide in the flue gas directly.
From there, repairs are often small. Reconnecting and re-screwing vent sections, correcting the pitch, clearing a blocked cap or adding combustion air can solve the problem. If the flue tube inside the tank is rusted through or the tank is leaking at the bottom, the heater is usually near the end of its life.
Repair or replace the heater?
Repair makes sense when the heater is otherwise sound and the fault is in the vent, the draft hood or the air supply. Our water heater repair visits often end there. If the tank shows rust at the base, water dripping onto the burner or heavy scorching, replacing it is the safer decision.
A replacement is also the moment to fix the vent properly. A new unit hooked to an old, sagging vent inherits the same leak. Ask the plumber to size the vent to the new heater and to confirm the combustion air. Our water heater replacement work covers that, and the price is given clearly before work starts.
Los Gatos rules for gas heater work
PG&E's advice for a gas smell is to leave immediately, avoid anything that could spark, call 911 from a safe distance, and then call PG&E. That is the same order we give you above, and the call to a plumber comes after it, not before.
Replacing a water heater with the same type in the same place needs a Town of Los Gatos permit, and the application can be made online. If the unit changes type or moves, the quick application does not apply and a regular building permit is needed, so ask your plumber which one fits your job.
The Town's bracing handout also asks for at least two earthquake straps, one in the upper third and one in the lower third of the tank. Each strap goes into a wall stud with a screw at least a quarter inch in diameter, driven at least half an inch into the wood, with a washer. Look at your heater's straps while you are checking the vent.
Heater in the hills or Monte Sereno
Heaters in garages or utility closets away from living space, as in many homes in the Lexington Hills area, can leak exhaust unnoticed. Put a working carbon monoxide alarm in the nearest hallway.
The 24/7 line dispatches plumbers around the clock to Monte Sereno and the rest of the area. If you are unsure whether what you smell is gas, call it in as gas. The utility would rather check a false alarm than miss a real leak.
Gas water heater exhaust questions from Los Gatos homeowners
Yes. If the flue or vent is broken, blocked or backdrafting, carbon monoxide can enter the room. It has no smell, so a working CO alarm and a visual check of the vent matter.
Leave immediately, avoid anything that could spark, call 911 from a safe distance, then call PG&E. Call a plumber only after the house is cleared. Do not turn the gas back on yourself, since PG&E must restore service after a shutoff.
It can be. Soot means the burner is burning dirty or exhaust is spilling out at the draft hood. Turn the heater down to pilot or off and have a licensed plumber inspect it before you run it again.
Reattaching a separated section with sheet metal screws is a modest job for a handy owner, but only if the pipe and joints are sound. If you see rust, soot or poor pitch, have a plumber check the draft before using the heater.
Yes. Our dispatch runs 24/7. For a gas smell, leave and call 911 and PG&E first, then call (855) 575-2890 for a licensed plumber once the house is safe.
A same-type, same-location swap uses the Town's online permit application, and a change of type or location needs a regular building permit. Ask your plumber to confirm which applies before the work starts.