4 Quick Steps to Save Your Motors
The two most common motor types in HVAC and plumbing applications are Open Drip Proof and Totally Enclosed Fan Cooled motors. ODP motors are typically smaller and less expensive and therefore used more frequently in indoor applications, however, even indoors the ODP motor is susceptible to corrosion and early failure. A rule of thumb that needs updating is OPD motors are ok for all indoor applications.
In closed coupled and vertical-inline CHW pumping applications the ODP motor shaft is connected to the submerged pump impeller via a rigid coupling. This coupling allows heat transfer between the impeller and motor shaft of a pump on standby to cool to below dew point at which time corrosive atmospheric water will condense on the motor shaft.
Left unchecked, your 15 year motor will fail in months. And don’t expect warranty replacement. The fine print will include statements that will absolve culpability due to installation locations within corrosive environments.
TEFC motors are not really totally enclosed, there is a weep hole, but they typically have a higher class of insulation, a coupling with a thermal break, and are covered for installations in wet and humid environments.
So to save yourself time and money do these 4 things:
Install TEFC motors in all outdoor and unconditioned indoor locations.
Verify thermal breaks between motor shaft and pump impellers.
Check to make sure there is no condensation occurring inside the motor housing.
Replace failed or failing ODP motors with TEFC motors if corrosion is suspected.