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View Full Version : I have met the air handler from hell this week...







hvac01453
04-07-2014, 03:12 AM
Original complaint. Condensate comming down thru the ceiling. Air handler was installed in a cramped space above kitchen apt. Looked at unit and water was forward of the cabinet and in the cabinet. Found pan rotted. No secondary pan (space limited) Customer issued replacement pan with extra length to include under the motor blower housing. Bad idea, it was sucking the water up, out of the pan, like a water spout. Ordered and installed OEM pan, still leaks. Pitched pan towards outlet a bit more severely, still leaks. Cabinet is level, found drain slow, and was reduced to 1/2" PVC, removed the drain from the equation with original 3/4" PVC and a condensate pump, still leaks. I cut the coil out last fall and power washed it clean assumed it was still clean, but noted it had black crude on a lot of the coil. Customer is non smoker but does burn candles often, so I chemically cleaned it with sodium hydroxide foaming cleaner to push the junk out, and it removed quite a bit, rinsed profusely. Still leaks. Saw sprinkles of water on blower housing after on for one minute...Had a Lexan panel made to see what was going on with cover in place, the side of the coil sheet metal had a small piece of sheet metal rotted off (by the tube sheet ends ) to prevent air from going around the coil. I cut and attached a blocking extention piece of sheet metal,and gasketed the panel side. No more spurts on the blower housing. But now the blower motor and housing have condensate forming on them and drip onto the insulation and then get blown forward and viola it's leaking again. These arn't a matched set, so I checked them and both are 2 ton heat pumps, I noted today the suction line wasn't sweating while 85F and about 70% RH... No frosting on the cap tubes in the air handler but sweating fine on the top 4" only, and not sweating down through all the U bends either, so she's low on gas....What is making the blower housing and motor sweat??? I even put a strip of aluminum buble wrap insulation on the leading edge on the housing (closest to the coil) where it sweated profusely.. I checked my delta T was 10F .... 80F return & 70F supply... Haven't returned yet, but after charging it up...will it drip??? What's going on??? Any ideas? Oh...the return is 14", should've fine...

Magoo
04-07-2014, 11:31 PM
Hi,
Low charge will lower the dew point in coil and increase latent cooling and moisture removal, adding charge and increasing SST in coil will reduce latent and increase sensible heat ratio /cooling. If fan casing is draw through/ negative pressure ensure there is a large water P trap in condensate drain.
magoo

monkey spanners
05-07-2014, 01:16 AM
I wonder if it is the fumes from the candles, it may make the water run off the coil differently, remember reading something similar in hairdressers with hair spray, but other than that and poor airflow i don't know!

hvac01453
08-07-2014, 03:24 AM
as far as the trap goes, I measured the draw with a magnahelic gauge and it was drawing only =.8"wc but since it is going into a condensate pump, and the trap is 4 or 5" deep Thats not the problem also the pump is pumping water so I know its draining... Since I washed it with Nubrite (potasium hydroxide) It foamed off good and clean. I'll see this week if the charge is the fix... confidence is low though......

MikeHolm
08-07-2014, 01:15 PM
What is your face velocity for air? Is it within the specs. Since it is hydronic, drop the fan speed and see what happens.