If your furnace is too large for your home, it is likely running in short bursts and then shutting off quickly. In some cases, this short cycling can be hard on your system, and it can also waste energy. If you have a gas furnace, you may be able to solve the issue with derating.
Derating is the process of reducing the amount of gas going through the burner of your furnace so that it heats your home more efficiently. However, this is a process that should only be done by a professional and to the manufacturer's specifications.
If you want to be safe, you should not derate your furnace on your own. Here's a look at the potential risks:
1. Rust and Corrosion
If you blindly derate your furnace by unplugging a few of the burner ports or otherwise diverting the flow of gas, you may accidentally derate it too much. As a result, the temperatures in the firebox (the chamber where the fuel is burned) may get too low, and the low temps may create condensation.
Keep in mind that the gas combustion involved in a furnace creates a lot of water vapor. The vapor typically exits your furnace through your flue pipe, but if it's too cold, it can condense inside the furnace. The droplets of water are likely to collect in the flue pipe and the corners of the firebox, and this can create rust and corrosion, damaging your furnace. The moisture can also affect the ductwork of your system.
2. Moldy Air Ducts
If you derate a system that does not truly need to be derated, it may start moving heat through the vents weakly. As a result of the reduced airflow, your vents can become cold, and condensation can occur in them. This can lead to moldy air ducts.
However, if you have a professional furnace repair person derate your system, they can ensure that they reduce the amount of gas being used by the furnace without reducing the airflow, and as a result, you don't have to worry about cold spots or condensation.
3. Uneven heating
Unfortunately, weak airflow can also have other effects. Namely, if your DIY derating results in reduced airflow through your ducts, that can cause your home to not heat evenly.
The air will likely travel through the vents to the rooms that are closest to the furnace, but then, the airflow will peter out before it reaches the rooms that are furthest from the furnace. As a result, these rooms will be colder.
4. Formation of Carbon Monoxide
The firebox is the chamber of your furnace where fuel is combusted to create heat, and the firebox in every furnace relies on a certain amount of air passing through it. If this amount of air is disrupted by inaccurately derating the furnace, some of the gas may not fully combust in the firebox. This can be very problematic.
If you have a modern furnace, it is likely powered by the combustion of natural gas, and if it's older or if you live in a rural area without natural gas, it may be using propane. Natural gas consists primarily of methane, which consists of one carbon and three hydrogen atoms, and propane consists of three carbon and eight hydrogen atoms.
If the methane or propane molecules aren't all combusted, they can split, and the loose carbon atoms from these molecules may bind with some of the oxygen that passes through your firebox. This process creates carbon monoxide. If that escapes from your furnace, it can be deadly.
To avoid all of these potential risks and to learn if derating is right for your heater, contact a furnace repair person, like those from Anytime Plumbing Services.