How is the primary air flow measured?
The only way to accurately measure the primary air flow is by reading the static pressure in the primary air plenum. A test opening provided in the unit for this purpose. When this pressure is plotted on the primary air flow V’s plenum static pressure chart provided with each project, the air flow can be read. Do not take readings in the duct near the unit and presume it will be the same in the plenum. It could be up to 100Pa out, or more.
 
Are inspections i.a.w. AS3666 necessary, and if so, at what frequency?
Yes, but only if the system creates condensate on the secondary coil. In this case, not usual for office building installations, the inspections would be the same as for any air handler with a condensing cooling coil. For the dry coil operation, the unit and drip tray should be inspected once a year for any foreign matter that might have found its way there.
 
How frequently do you need to clean lint screens?
Very infrequently. It is recommended that in the first year of operation, an inspection be made after three months operation. If clean, make it six months to the next inspection. Based on recent installations, yearly inspections should be adequate. Refer also to Item 'Comparing Systems' earlier in these FAQ’s.
 
Can the capacity of a terminal unit be altered after installation?
No. At least, not easily if the intention is a change to the design total capacity of the unit. The load varies in normal operation by varying the secondary water flow. The primary air pressure and number of nozzles set the primary air quantity, a constant flow, with variations in air temperature to the outdoor air temperature schedule.
 
If the unit had small nozzles, these might be changed to the medium nozzles to increase the primary air figure. This should be referred to the Dadanco technical staff. There may have been additional holes provided for nozzles that were plugged at time of manufacture. This is not the normal case. If it were so, the plugs could be replaced with nozzles. This assumes the primary air system can supply the additional air.
 
The units are not intended for field alteration and any proposal to do so should be referred to Dadanco.
 
Can the handing of the secondary coil be changed in the field?
Yes. While the unit will be supplied with the coil orientation agreed prior to manufacture, the coil can be changed in the field. The coil is retained with brackets, which can be removed, the coil rotated and the brackets replaced. There will also be changes to the connecting piping – but it can be done.
 
Will condensation occur if I have bad or poorly maintained controls?
It could. You should have them fixed! With the quality controls you have installed, the sensors will have detected the change in secondary water temperature and/or the high room dew point and will have initiated the pre-arranged controls program to raise an alarm with the maintainer; to reset the secondary water temperature upwards. As a last resort, the program will stop the secondary water pump until the fault is corrected.