A weak flame happens in the furnace because of venting issues, which can either be that the exhaust vent and intake vent are too close together, or that the intake vent could be blocked by dirt and debris. You will notice a weak flame in the furnace either because you have seen it or because your home is not heating up as quickly as it normally does. This can waste energy and cause your energy bill to become higher if you have to turn the heat up more in order to get it at the proper temperature. Here's how to resolve this issue:
Test for a Blocked Intake Vent: If the intake vent is blocked, then the flame isn't getting enough oxygen that it needs to become stronger. You can test this issue by removing the burner cover of the furnace. After you have done this, if you notice that the flame has been improved, then this means that the intake pipe definitely has been blocked and you will want to clean it out with a sink auger. There are a number of reasons that this could happen to the intake vent of your furnace. Sometimes, birds can get into the vent and build a nest or, over time, a great deal of dirt and dust may have gathered causing the heavy blockage.
Improper Vent Pipe Installation: Another reason that the flame could be weak in the furnace is that the vent pipe installation was done wrong. Most likely, this is the case if the weak flame is not due to a blocked intake vent. An improper vent pipe installation can cause short circuiting in the furnace or the vent pipes could be too close together, which cause fresh air to mix with the exhaust gases. Exhaust gases consist of carbon monoxide among other gases that can lower the level of oxygen that is going to the flame, which then makes it weaker. You can easily fix this issue with a concentric vent kit from your local hardware store or by contacting a local heating repair service.
By resolving the issue of a weak flame in your furnace, you can get your furnace to begin to perform efficiently so that you can heat your home without having to increase your energy bill each month. Without resolving a weak flame issue, you will notice that you have to turn the heat up significantly higher in order to see your home at a comfortable temperature.