Thermal Imaging (Case Two)
Case Two: Why Does My Boiler Keep Failing?
Building Type: Water Treatment Plant.
HVAC System: Hot water radiant heating serving three (3) zones.
Complaint: Client says his boiler cracks and leaks every several years. Also, high humidity and low comfort.
Complaint Type: Comfort, energy, and equipment life cycle.
Effects: Poor boiler performance. Short equipment service life. Poor space conditions.
Cause: Radiant heating is used throughout the water treatment facility to prevent high humidity and condensation collection on surfaces. The plant was renovated in the 90’s. Ever since the renovation they have replaced the boiler serving the heating system every few years due to cracks and leaking. They were originally running the water temperature in the plant at 160 to 180 degrees. Now they run the boiler from 180 to 200 and can never get the space temperature and humidity where they want it in one zone. During the renovation, the envelope of the building was sealed and insulation was added. Space pressure is at slight positive, just where it should be. After walking the plant with my FLIR T620 camera, the story started to write itself. The boiler was suppling 180 degree water. Image Pair 1 shows three circulation pumps used for the radiant heat zones. Zone 1, serving the ground level, was returning water at a temperature of approximately 160 degrees. Zone 2, serving the ground level, was returning a water temperature of 155 degrees. Zone 3 (largest zone), serving the lower level, was returning a water temperature of 138 degrees.
Image Pair 1
Digital image of radiant zone pumps
Thermal Image of radiant zone pumps
We already know the cold return water is the problem with the boiler because of the condensation causing the boiler to fail. But why?Image Pair 2 indicates that none of the piping serving the lower level has insulation.
Image Pair 2
Digital Image of radiators and piping
Thermal Image of piping
The total length of this piping loop is approximately 500 feet. Since all of the piping runs parallel and in contact to underground concrete walls, a great deal of heat is lost to the walls and not the space.
Solutions: The insulation was replaced and the boiler runtime was greatly reduced, the return water temperatures were back above 140 deg F and the space was much more comfortable with reduced humidity. A cost benefit analysis was performed and the saving were quite impressive with a very short payback (another subject entirely).
