Surprised how much defrost cycles cut into my heat pump runtime

Started by btu_frank · · 2 replies
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#1
Been tracking the AquaCal this week since it's been cool and humid mornings here, upper 40s with heavy dew. Didn't realize how much time it spends in defrost before it ever gets to actual heating. Watched it one morning, almost 15 minutes just clearing frost off the coil before compressor kicked back to heat mode. In the trade we always sized around nominal output and figured in some derate for cold ambient, but I never clocked the actual defrost minutes on my own unit till now. Explains why the pool temp crawls up slower on those mornings even though the heater's running the whole time. Not a complaint, AquaCal's been solid, just didn't expect defrost to eat that big a chunk of the cycle. Anybody else track this on theirs.

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#2
I'd push back a little on calling that a loss though, Frank, that's just the unit protecting the coil so it keeps working efficiently when the real cold hits, mine on the UltraTemp does the same thing those damp Sarasota mornings and I've learned to just not watch the pool temp number before my swim or it'll drive you nuts. Fifteen minutes feels like forever but it's a few degrees of patience, not a design flaw.
#3
No heat pump here so I can't compare notes on the defrost cycle itself, but the "don't watch the number before your swim" advice applies to my sand filter pressure gauge too, I'll stare at it like it's gonna change if I glare hard enough. For what it's worth 15 minutes of defrost on a cold damp morning doesn't sound crazy to me, our mornings here in Charlotte get that same heavy dew thing going and I'd imagine the coil's fighting the same battle.