Retrotec DU200 DucTester with DM-2 - Manual

SP802 Page 1 of 2 rev-2012-02-14
Residential duct leakage
measurement equipment comparison:
DucTester & Duct Blaster
®
Use this guide to compare features of the two top US manufacturers.
Retrotec’s DucTester
Speed control located inside the fan and connects to
gauge with umbilical that includes an Ethernet speed
control cable and all tubes.
The Energy Conservatory’s
Duct Blaster ®
Speed control located on the power cord and
connects to gauge with a mini jack.
Duct tester performance and applications
Duct testing standards for new houses typically limit the maximum acceptable leakage to 80 to
150 CFM whereas existing houses can have leakage up to an astonishing 300 CFM and still pass
some code requirements. Leakage above 300 CFM is difficult to measure because the air-
handler’s blower wheel would then represent a significant resistance and obscure leakage on the
supply side. Both duct testing systems will measure leakage well above these maximum
leakages. Both systems have about the same flow rate when depressurizing ducts which is the
easiest direction to test in because the negative pressure holds on the seal over the registers.
It was common practice to measure air handler flow rates using a duct tester but this method is
seldom used because neither unit can duplicate a 5 Ton system which could have 2250 CFM of
air-handler flow.