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724-746-5500 | blackbox.com
Chapter 4: Maintenance
Drain port
Female coupling
(supply manifold)
Male coupling
(return manifold)
Fins (behind
perforated sheet)
Figure 4-2. Top-feed model.
NOTE: Although water exposure is not likely, you might prefer to place some water-absorbent material beneath the HTD as a
general practice when performing procedures on the HTD.
4.1 Purging Air from the HTD
Perform this procedure as part of regular maintenance and when you hear a splashing or gurgling sound from the manifolds.
CAUTION: Wear safety goggles or other eye protection whenever filling, draining, or purging air from the HTD.
1. Unscrew and retain the caps from both air-purging valves (on bottom feed models only).
NOTE: The valves are similar to the valves on bicycle tires.
2. Place one end of the long hose of the air-purging tool into the bucket to catch the water that escapes during the purging
procedure.
3. Attach the other end of the long hose to the leftmost (supply) air-purging valve. As the air-purging tool is screwed on to the
valve, water that is mixed with air will begin to spit into the bucket.
NOTE: The 6”/16 cm extension hose is used for draining the HTD; it is not required for this procedure.
4. When there is a steady stream of water from the air-purging tool into the bucket, unscrew the air-purging tool from the valve.
