Amount of Carbon Monoxide & Other Noxious Gasses From Condensing Furnace Question

PGB1

Hi All,

The neighbor next door had what I think is a condensing furnace installed. The reason I believe it is condensing is because the vent is PVC through the basement wall. (I don't know much of anyting about such furnaces & boilers.)

The wall with the vent is on the side of their house which is about 10 feet from the side of our house.

The question I have is how much noxious gas is left when the furnace discharges from the pipe? The reason I ask is that the vent is about 12 feet from our patio and the windows on it and about 10 feet from 2 windows on the side of the house that we often open in heating season.

I noticed today that I can feel the air moving from the patio. When the furnace noise stopped, so did the air movement, so I am assuming the exhaust what I felt. Our concern is more of our dog breathing something noxious. (Not too keen on the noise, either.)

Thanks for your advice,

Paul

Jamie Hall

Well now. That depends a lot on how well the burners are adjusted and maintained. The two gasses of concern are Carbon Monoxide and various oxides of Nitrogen. If the burners are correctly adjusted and maintained, Carbon Monoxide will be at or nearly zero — not enough to worry about. The Nitrogen Oxides will be low, but not zero — and you will smell them as a rather distinct acrid smell. Hard to describe, but once you have smelled it, you will know it. At any reasonable concentration they too are not a problem to health.

If the burners are poorly adjusted, the Carbon Monoxide can rise rather high.

Now. Before becoming alarmed. Even a remarkably poorly adjusted boiler will not reach the Carbon Monoxide levels from a gas grill or a gas stove, never mind a charcoal grill. The nitrogen oxide levels will be on the order of the levels of a moderately busy street, but lower than a freeway or a major urban street.

PGB1

Thank You Jamie Hall for your helpful explanation. I very much appreciate your sharing of knowledge.

Paul

pecmsg

3’ is normal code to any opening. 10’ is more then enough

PGB1

pecmsg: "3’ is normal code to any opening. 10’ is more then enough"

Boy did they miss!

The exhaust is about 12" directly under a window, that coincendentally is open right now. It's also horizontally well within 3 feet of another window. (Not my house.)

neilc

that's some patio

PGB1

Aint' my patio.

Mad Dog_2

Are you growing your own? Ha ha..

Mad Dog

jesmed1

I installed our Jotul Lillehammer direct vent gas stove. It's the smallest one they make, just 18,000 BTU/hr input. But the vent clearance requirements from operable windows are surprisingly small. The instructions allow for the vent to be within 9" of an operable window (or door).

I would have preferred to install the vent farther from a window, but the installation was in our sun porch which has many windows, so it was impossible to get more than 12" away from any window opening. I did the mechanicals myself and had a local plumber run the black iron pipe for the gas line. The town inspector came, I showed him the vent clearance requirements in the installation manual, he said we should put a CO detector in the room (I already had put one nearby and showed him where it was), and he signed off on it.

Obviously a larger furnace with a higher BTU output will produce more CO, so your neighbor's install may or may not be problematic. But I was surprised at how small the required clearances were for this Jotul Lillehammer direct vent.

DavidK_2

This is not really a steam heating related question. You might have posted in the wrong forum. I don't think they make condensing steam boilers. But I could be wrong.

I would not worry about noxious gases from 12 feet away. They should be well diluted before they reach you.

Usually a condensing furnace should be pretty darn efficient. My guess would be the neighbors new furnace emits less toxic gas than their old one did.

I'm actually surprised you can feel the air movement from that distance. Perhaps they also installed an air to air heat exchanger? The fan used might be more powerful than that used on a furnace. I do not know.

Do you smell anything when their furnace is running? Dogs have a pretty sensitive nose, I assume they would move away from something they did not like the smell of.

PGB1

DavidK_2 asked if we smell anything & commented about the dog. That's an interesting thought, so I observed.

My wife says that she can smell something "chemical". Perhpas it's the new PVC off-gassing. I don't smell anything, but that doesn't mean much. My smellifier isn't the greatest.

But the dog's reaction was interesting. Whenever either of the neighbors is outside, he runs to the fence and stands with paws on the top rail. (Attention getter). This morning the furnace was running and the neighbor was outside near the vent. The dog ran to greet him and did a quick u-turn ust short of the fence. It seems that the dog is smart enough to avoid the gasses, so my concerns about his health are now abated. (Unless it was the, assumedly temporary, PVC off-gassing he was smelling.)