Page 211 - Boiler_Operators_Handbook,_Second_Edition

196 Boiler Operator’s Handbook

problems with occupant comfort and resolve them or warranty so the problem belongs to someone other than
provide the owner with your analysis and suggestions the owner, you should try to identify changes in load to
for what a contractor would be needed to do. see if they can be rectified. Look for any changes that
increased the load and inform the owner of them.
Data Collection and Analysis To check a problem with an AHU or RTU collect
Using a psychrometer depends on what type you and record the actual temperature and air flow data for
have. Call me old-fashioned but I prefer to use a good that unit and mark a copy of the pyschrometric chart
old sling psychrometer, the one shown in Figure 5-50. you prepared with that unit’s design data to see what
All I have to do is check that the wet bulb portion has might be off.
water in the reservoir. You can use an electronic gadget Since the air carries the heat away, or delivers it to,
but I suggest you make sure it’s calibrated every time the occupied spaces a lack of adequate air flow should
before you use it for serious work, especially if you’ve be addressed first. Problems with unit air flow are com-
dropped it. Yes, I’ve dropped the sling, and I’ve tapped monly dirty filters followed by loose fan belts. For rooms
some furniture while using it several times, but I haven’t and zones VAV box filters should be checked followed
broken it yet. And, since the gradations are on the ther- by isolating a loose splitter damper, control damper,
mometers it’s always right if it isn’t broke. dirty reheat coil, and failed or damaged ductwork. Note
Progressively isolate the problem, determine if it’s changes in the space that might have produced the prob-
just one room, one zone, or affecting everything served lem; I recall one where a contractor replaced all the ceil-
by one piece of air conditioning equipment. Then check ing tile in an office area, including replacing the return
the obvious things: Is the equipment running? Does it air grills that allowed room air to return to the AHU.
have electric and control power? Has someone tampered The project manager told me the contractor complained
with the thermostat or done something to block air flow? that he had to clip down all the new ceiling tiles because
In checking a problem with a room or zone col- they kept popping up. Other unique problems included
lect and record room and supply air temperatures then one where a contractor adding sprinkler piping had re-
use the flow hood (Figure 5-47) to measure the air flow moved the flex connections between the ductwork and
through the registers. If the difference between room air registers to get the pipes into the ceiling space. That was
and supply air temperature is equal to or exceeds de- revealed by return air temperatures considerably differ-
sign, air flow through the registers is equal to or exceeds ent than room air temperature; the air was flowing, not
design and supply air wet bulb temperature is equal to into the room but bypassing it.
design or when cooling less, when heating more, then I could fill this book with many more stories, each
the system is working properly. That normally means a lesson in what can go wrong, but you’ll have to apply
the load in the room or zone is more than design and the what you understand the systems are supposed to do to
equipment simply can’t handle it. isolate problems with them. I can’t possibly tell you ev-
Unless it’s a new facility, which should be under ery possible scenario within the page limit of the book.

Figure 5-50. Sling Psychrometer Figure 5-51. Infrared Thermometer