So ... are you saying that only healthy people who refuse to take risks with their health have the right to breathe clean air or complain about polluted/toxic air? Would that apply to your family? After all your making that decision for them if you install an unvented appliance in your home. Would you ask them how they felt about it? Explain the potential risks? Ask them if they as a family would like to persue a healthier/safer way to install said appliance? Just wondering how this ends up when it is your family & their lives on the line, or would you justify the risk & not say a word knowing/believing that you are saving a few bucks & that makes the risk worth it? BTW if you are living in a 150 year old drafty house, I suggest you invest in air/vapor barrier as well as insulation. You may find the need/desire to take a risk with so much on the line vanishes when you can keep the cold out, as opposed to using the cold & drafts as an excuse to bring the exhausts in to the space where your family lives.