When upgrading to a high efficiency gas furnace in your O’Hara home, you may need to make some upgrades to your chimney. Older chimneys built for standard furnaces with normal exhaust needs are not built to the specifications needed by today’s high efficiency models. Not only is it unsafe to leave it as is, but the cost of repairs if you don’t have it upgraded can be substantial.
A common concern when upgrading to a high efficiency gas furnace is the issue of condensation and draft. Because the amount of exhaust being vented is reduced by a high efficiency furnace, your current setup is not sufficient for the new model. So, it needs to be reduced in size by a professional to avoid backup of exhaust. Proper chimney sizing is a complex process that requires professional guidelines and careful measurements of all appliances in your home.
Because the chimney often isn’t used at all for a high efficiency furnace (often PVC pipe used instead), the extra airflow in the chimney can become a major issue.
The biggest concern for the chimney when changing the furnace efficiency is condensation. Specifically, acidic condensation droplets can build up in the chimney if not properly stopped. A new chimney liner must be placed in the chimney to avoid excessive corrosion due to the acid droplets. Keep in mind that the efficiency of your new furnace will determine whether you will use the traditional chimney for exhaust or if a new line will be installed to vent your furnace.
When to Take Action
If you have your furnace replaced, your O’Hara technician will likely discuss the chimney situation in your home with you. Keep in mind that this might be necessary and that there might be an added cost involved because of it. Modern furnaces are not designed to accommodate aging chimneys and your safety and the integrity of your house are at risk if you don’t retrofit the chimney if necessary.