Furnace Features - Multi-Stage Furnaces

We are now officially in the holiday season with Thankgiving last week. This is the time of the year when we get all the furnace service calls. And if your furnace is older than 15-20 years and is starting to give you problems, you should consider replacing the furnace with one that has features that were not available when the original one was installed.

Speaking of which, we shall continue on the series of articles on residential furnaces. The feature we will cover today is multi-staging.

The older style furnaces are all single staged, which means they operate on their full capacity (eg. 70kBtu/h) whenever they are on. The most common multi-stage models for residential furnaces are 2 stage. They can operate at their full capacity (i.e. high stage) or at a low stage which is roughly half the full capacity.

There are two main benefits to a multi-stage furnace compared with a single stage model. First, the furnace operates at a quieter level. This is the result of the recirculating fan running at a lower speed and roughly half the burners are in operation. Second, the system stays on at longer intervals which keeps the house at a more even and comfortable level. Both benefits are very desirable and in my opinion a very good value from a cost-benefit standpoint.