Duct work

Properly installed duct work

Duct work

Properly installed duct work

The basics of an HVAC system

There are 3 main factors that go into determining if your furnace will work at its peak efficiency. They are:

1. The furnace itself
2. The duct work
3. The installation

If any of these has a problem, you will know that your furnace/air conditioner is not working to its full capacity. This blog post will deal with the least sexy part of this sytem: the duct work.

The job of duct work is to distribute hot/cold air all through the house equitably. When the duct work is installed properly, the furnace or AC keeps all rooms in the house at a comfortable temperature.

An improperly installed duct system would render your home uncomfortable even if the furnace or the air conditioner is sized correctly for your home and functioning properly.

This is analogous to buying a Mercedes-Benz S-class with tires and inner tubes from the 1970s. Sure, the automobile is high end, but without good tires, you are not going to get the pleasure or the comfort of driving such a exclusive vehicle.

Improperly designed or installed duct work lowers the efficiency of the equipment. If there is a leak in the duct work, your energy bills will be higher even though you may have bought an energy-efficient furnace/AC. The same is true if the duct work is not insulated.

Is your furnace is working to its full capacity?


When you buy a furnace, the equipment comes with the specifications that tells you the temperature rise of the equipment. To see if your furnace is working to its full capacity, turn up the thermostat to 5 degrees over the ambient temperature. This should turn the furnace on.

After about 15 minutes, check the temperature in the register closest to the furnace. You can use a meat thermometer for this. Then check the temperature in the return air.

The temperature difference between the two should be within the range specified in the factory specifications for temperature rise.

If it is not within this range, check the furnace filter. If it is dirty, replace it. Next, make sure that the supply and return registers are not closed or obstructed in any way.

If both these are ok, then it is time to call your HVAC specialist.

RC Mechanical is an owner-operated Redwood City business and provided expert furnace and air conditioning repair and installation to the Bay Area with integrity for over 20 years. Homeowners in Redwood City and throughout the Bay Area count on us for all their heating and air conditioning needs.Call us today at (650) 575-3915.