With the economy slowly turning around, new home construction has started to pick up again — this is good! Since new home construction is making a come back, it is time to remind everyone about the practice of using the furnace as a “construction heater”.
It is a common practice to use the central furnace as a construction heater during the finishing phases of construction on a new home. This practice can cause major problems for the appliance.
In all the installation instructions that I have read from manufacturers, they all have this wording in those instructions: THE FURNACE IS NOT TO BE USED FOR TEMPORARY HEATING OF BUILDINGS OR STRUCTURES UNDER CONSTRUCTION.
Why don’t manufacturers want the furnaces used for temporary heating in new construction?
- This practice forces the furnace to operate under unusual and abnormal conditions (ie. very low return air temperatures). Furnaces operating under these conditions can lead to the formation of condensation in the furnace and/or vent system even though the appliance may be a non-condensing furnace under normal conditions.
- Using the furnace as a construction heater exposes the furnace to an atmosphere which has the distinct possibility of being corrosive. Typically, in the finishing phases of construction, chlorides from sources such as paint, stain, varnish, tile and counter cements, adhesives, and foam insulation are present in the structure. A corrosive atmosphere combined with condensation is a recipe for trouble.
- Often time the return air filter is removed or the furnace is run with the doors off. This allows “construction dust” to enter the furnace in areas such as the heat exchanger, blower housing and wheel, burner area, and venting system. On 90+% efficient furnaces, the secondary heat exchanger can become plugged on the fins reducing air flow and heat transfer.
If you are going to use the furnace as a “construction heater” then you MUST follow these instructions as we now list in our current installation instructions:
In essence, the furnace must be completely and properly installed with all doors in place. Before turning the house over to the end-user, the furnace should be completely cleaned and a complete start-up performed on the unit to assure proper operation and that the new owner will be getting an appliance that will be reliable and functioning for years to come.