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wingless' Buried AC Condensation Sump Pump

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The AC condensation pipe at my southern Florida AirBnB has always been problematic. The internal condensation water is supposed to drain to the exterior of the house, but stops draining properly, then that abatement of flow is detected by the float switch, interrupting the AC operation. The AC stops and the Next thermostat shows loss of power, because the float switch is wired to interrupt the 24VAC transformer power.


This is a single story four bed / two bath beautiful home, with the AC air handler / evaporator in a hallway closet. The water condensation line is routed down through the slab floor, then 20' sideways to the compressor / condenser exterior concrete pad.


The problem is that they then put a 90° UP bend on that buried 3/4" Schedule 40 PVC pipe to pop up through the AC pad to then dribble onto the ground next to the pad.


The open end of the interior pipe is higher than the exterior end so it sort of worked okay, until the buried pipe w/ "science experiment" stagnant water became funny and it stopped draining.


My ongoing long-term "solution" had been to periodically use my wet / dry vac to suck out the disgusting stagnant water in the pipe to restore "normal" draining.


The last few times I was unable to suck it clear. The final time I was unable to suck at all.


Fortunately I had already been planning for a proper solution and had already purchased / received this Little Giant AC sump pump and this Rain Bird VB-STD large rectangular buried valve box.


Note that the sump pump Owner's Manual states in the NOTICE section, "Pump is for indoor use only." My thought is the deep / walled / covered location is sufficiently dry, so I think I'm good even though this is an exterior installation.


My plan was to dig next to the AC concrete pad, cut the drain pipe and route it to this buried sump pump, cover it all w/ the valve box and put a properly wired nearby exterior GFI receptacle for the power.


Every bit of earth in southern Florida is a miss mash of crisscrossed roots, so I use my OMT to aid in that part of the digging effort by cutting the roots, some of them 3" diameter. So I dug down, then dug sideways under the pad until I reached the pipe. Then I kept digging down until I reached the 90° elbow. That was about 2' down. I then dug the pit where the pump is being placed to an appropriate depth. 


The pit was being dug in a narrow alley, w/ no room for piling dirt. I used containers to hold the removed Earth There were three box shaped recycling totes that were filled, then a 50 gallon wheeled barrel was filled. (All the roots tossed to the side and discarded.) During replacement the 50 gallon was emptied back into the ground and part of one of the box totes was returned.


The bend and the upward pipe was cut off. Instead of a rush of horrible water, the slow dribble of water continued. I attached the wet / dry vac, then eventually got massive glugs of that horrible water, until that pipe was empty. I ran a snake through that line and encountered nothing (at that point).


The walls of the pit were lined w/ overlapped brick-shaped pavers to an appropriate height so the valve box top would be flush to the ground.


The pipe was routed so it drains into the box. The 90° downward bend was not bonded onto the horizontal pipe in case future removal is ever required.


All the Earth was replaced and packed in place using my mini Thor hammer.


The new GFI receptacle was added to provide power.


Future updates include using the existing pump over full switch w/ pigtail wires. That will be routed to a white 12V lamp and blinking amber lamp w/ audible alert. Those will be placed to be visible / heard on the entrance camera. My thought is the likely possible problem is the GFI faults, killing the pump power. This won't cause a problem for the AC, as the water will just dribble into that new gravel bottom pit, but will eventually cause a mess, in the pit, not in the house. A different AC power circuit will have a 120VAC to 12VDC power brick, so the white lamp will permit visualizing power of that circuit and the blinking / buzzing will permit remote detection of the problem, from my home computer.


Another option for that existing over full switch is to interrupt the AC operation or to drive a relay. This chosen alert method is the best for this remote application. It permits AC operation and alerts me of the problem.


That low voltage alert switch may be configured for Normally Open (NO), used for the alarm described above, or configured for Normally Closed (NC), to interrupt the 24VAC powering the thermostat to shut off the AC when the pump gets over full.






















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