On May 4, 2:35*pm, "Stormin Mormon"
wrote:
Monoxide is a clear, colorless gas, about the same dentisty as air. Wouldn't
lead to soot.

* *http://www.carbon-monoxide-poisoning.com/symptoms.html
Stuffy nose, not on the list.


Soot indicates insufficient air to burn the fuel.
Insufficient air can also lead to CO formation instead of CO2

So sooting is often accompanied by CO (Carbon monoxide) production.
Silent, odourless and deadly.

Did Jesus never tell you this?

So the OP needs to determine what's going on get this fixed uregently.
In fact shut the system down until it is sorted out.