Condensation on OUTside of air handler?
Odd thing. Friday night, fan but no cool in upstairs heatpump system (4-ton horizontal-right Carrier; installed in un-insulated, vented attic about 1995. Shake roof, big old house, very air-permeable).
Upon checking, the galvanized drip pan underneath the whole unit was full of water to 1-1/2″, and the float microswitch had tripped out the compressor. No prob, just pumped it into the drain on the condensate line with a hand pump. My HVAC guy installs a microswitch rather than a drain on the pan, so you’ll know there’s a problem before it just goes on forever.
But – looking for the leak. The air handler sits on four bricks and rubber pads in the pan, say 3″ gap from the bottom of the sheetmetal to the bottom of the pan – all pretty level. Looking under with a flashlight, the entire underside of the air handler is evenly covered with little drops of water (no apparent rust) – it immediately reminded me of the condensation on the ceiling of the refrigerator in this really humid Georgia weather we’re having.
We run the upstairs only at night – daytime upstairs gets to 86-88, we turn it down to 80 at 8 PM until about 5 AM.
Anyway – pulled off the side panel over the A-coil (well, maybe the “>” coil). The drip pan is plastic, and appears intact – no obvious cracks or rust stains, no standing water, no clog in the primary drain.
So – before I really dive in, any chance that humid air is just condensing on the underside outside of the air handler and dripping into the pan? Seems like wishful thinking, but I can’t see how a one-piece plastic drip pan under the coil would suddenly spring a leak.
Forrest – not a HVAC guy
Replies
When you start it up again, measure the case temp and compare to dew point in the humid weather you are having.
Otherwise, look for a small embrittlement carck in the plastic. How old?
Edit PS: HF had a laser pointer IR temp gauge onslae for $20 not long ago, think they are only $30 normally - just the thing for this type temp measurement.
Edited 8/16/2009 10:03 am ET by junkhound
Definitely below the dew point - I've got a non-contact infrared at work I'll get. The way we run it, it might run 3-4 hours straight when we turn it on at 8 PM - plenty of time to get and stay cool.
Forrest
In memphis we are as humid as you... and this is pretty common... we install drain lines from the drip pan also... to cover this.. if there is no way to drain it... then we install a pump with a float that the pan drains into...
look at your galv. pan... does it look like there has been water in it before? maybe it usually just evaporates before it can cut off your unit?...
if it looks like it has never had water in it before... i'd look for a leak in your plastic pan inside your coil box.. it could be stopped up even... stuff can grow in there... use compressed air to blow it out...
p
I didn't see rust inside the external drip pan - but I'll look. We've had afternoon thundershowers the last few weeks, and 95-plus temps, so often walking outside is like stepping into a wet dog.
Forrest