UltraTemp making a new rattle only when it's cold out

Started by Chuck Weaver · · 1 reply
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#1
Woke up for my morning swim last week and noticed the heat pump had this rattle going, wasn't there a month ago. Only happens when it's actually cold, like below 60 out, once it warms up midday it runs dead quiet again. Fan blade looks fine, nothing loose that I can see or feel when I put my hand on the housing.

Mine's the Pentair UltraTemp, four winters now with no issues before this, so I'm hoping it's something dumb like a panel not seated right after I had the cage rescreened and the guys were poking around out there. Anybody run into a cold-weather-only rattle like this before I call someone out for a service call. Not in a rush since it's still heating fine, just don't want to ignore something that turns into a real problem come summer.

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#2
Whoever said check the panel screws first is right, cold makes sheet metal contract just enough that a screw that was fine at 90 degrees starts to buzz once it's 55 out. That part gets left out a lot though, it's not usually the screws going loose, it's the rubber isolation feet under the compressor or fan shroud getting stiff in the cold and not damping vibration like they do in summer. Had a customer last week with the exact same complaint, panel was torqued down fine, turned out one of the rubber feet had a hairline crack and only made noise once it got cold and hard.

Since you had guys out there rescreening, I'd still bet on something they bumped, but don't stop at panels, run your hand along the base and those isolation feet too while it's making the noise. If it's fine mechanically and just an intermittent contraction rattle, plenty of UltraTemps do that for years and never turn into anything, mine's on year six with a similar tick that only shows up under 55.