HVAC systems do not ‘live’ forever, but most tend to be in service long after their life expectancy has passed. Replacing the HVAC system is not a glamorous project that generates much excitement – unless it’s dead and there’s no heat/cooling. Then, it gets top priority.
HVAC systems should be evaluated for replacement if they are more than 20 years old (highly subjective to how they’ve been maintained and the environment where they are located) or if the facility they serve has had a significant change in function. For example, if the facility is heated primarily with a make-up air system because it used to be a production area that required a lot of fresh air, but now it’s a storage area, then the heating system should be replaced. Another common example is a facility that used to have a steam process that is long gone, but the same central boiler that used to supply the process and space heating is still used for space heating. In this case, the boiler is probably way over-sized for the current load and may not be well maintained because it’s not needed for an industrial process.
See Space Heating for information on different types of heating systems.
Forced Air Systems
See Boiler Efficiency Tips in the Boiler Efficiency Improvement Section
Source: Text Bob Fegan 1/2009;