Condensate Floor Drain Overflowing

[RobS2244]

I recently moved into a new house. We have 2 condensing units outside. One of them wasn't working, so we had a service repairman come out and take a look. He came out and determined it needs a new compressor (this is unrelated to my question). Anyway, he put refrigerant in the already working condensing unit, saying it was very low and he was surprised it was still putting out cold air. As far as I know, that is all he did, but I was not there so I cannot confirm with 100% certainty. Anyway, the very day he left, condensation from the furnace in the basement, which relates to the already working condensing unit, was coming out of the condensate line at a fast pace and filled the hole in the concrete of the basement that the condensation drips, and apparently drains, into. I note that the hold just leads to dirt. The hole had never overflowed in the 2 months prior. The condensation is dripping at 1 to several drops per second when the unit is running. I don't know what the pace was prior to the repairman's arrival. I have attached some pictures, which hopefully help.

My questions are: Does this setup look correct? From my research, it looks like the condensate line should be run to the outside of the home to drain, rather than just draining into dirt under the home. Is it possible that this line is a auxiliary/failsafe drain and the primary line (perhaps going outside) is not working correctly. I know the home inspector noted in his report that the condensation drains outside by the condensing unit, but I do not see where. Also, I do not see another area on the furnace where there would be another condensate line. Could the repairman have shut a drain off somehow? I do not see a line pump, unless it could be inside the housing of the furnace. It just seems too coincidental that the floor drain overflowed for the first time within hours of the repairman coming.

I really appreciate anyone's help on this.

 

[Dana]

In most cases condensate from the coil in the air handler unit would drain into a condensate pump, since even with slab-on-grade foundations there often isn't enough slope to accommodate a gravity drain. The condensate pump is usually/often directed outdoors to daylight, but sometimes to an indoor sump, floor drain, laundry basin, or some other legitimate drain.

Drilling a hole through the slab to dirt is not a legitimate way to deal with it.

Regarding the coincidental increase of condensation after the visit, if the system was previously under-charged it's likely that most of the coil in the air handler wasn't as cold prior to topping up the refrigerant, which would produce less condensate. With the system properly charged it's now runs cold enough to condense more moisture out of the air. So in that sense it's not a surprise.

If the system was still keeping up with the temperature setpoint when severely under-charged it's an indication of the unit being substantially oversized for it's actual loads (all too common.) With the proper charge the run cycles and total duty cycle will be lower, but it will run more efficiently (even when oversized) than an under-charged system. If you measure it's duty cycle on the days when it's near your 1% outside design temperature you can use that to measure fairly accurately what your actual 1% cooling load is. Even though it doesn't look all that old, if it's leaking refrigerant it may soon be time to consider retiring/replacing it, and when you do it's better for both comfort and efficiency to right-size it with no more than 1.5x the capacity needed at the 1% outside design temp- 1.25x and multi-stage or modulating would usually be better, but there's a range.

If it comes to that and turns out the AC is 2-3x oversized, it's highly likely that the furnace is also oversized, which you could determine by correlating heating degree-days against fuel use during wintertime intervals between meter readings using this methodology. It's often the case that a right-sized heat pump will fill the bill for both heating & cooling, and provide better heating season comfort than the usual 3x oversized gas burner.

 

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[RobS2244]

In most cases condensate from the coil in the air handler unit would drain into a condensate pump, since even with slab-on-grade foundations there often isn't enough slope to accommodate a gravity drain. The condensate pump is usually/often directed outdoors to daylight, but sometimes to an indoor sump, floor drain, laundry basin, or some other legitimate drain.

Drilling a hole through the slab to dirt is not a legitimate way to deal with it.

Regarding the coincidental increase of condensation after the visit, if the system was previously under-charged it's likely that most of the coil in the air handler wasn't as cold prior to topping up the refrigerant, which would produce less condensate. With the system properly charged it's now runs cold enough to condense more moisture out of the air. So in that sense it's not a surprise.

If the system was still keeping up with the temperature setpoint when severely under-charged it's an indication of the unit being substantially oversized for it's actual loads (all too common.) With the proper charge the run cycles and total duty cycle will be lower, but it will run more efficiently (even when oversized) than an under-charged system. If you measure it's duty cycle on the days when it's near your 1% outside design temperature you can use that to measure fairly accurately what your actual 1% cooling load is. Even though it doesn't look all that old, if it's leaking refrigerant it may soon be time to consider retiring/replacing it, and when you do it's better for both comfort and efficiency to right-size it with no more than 1.5x the capacity needed at the 1% outside design temp- 1.25x and multi-stage or modulating would usually be better, but there's a range.

If it comes to that and turns out the AC is 2-3x oversized, it's highly likely that the furnace is also oversized, which you could determine by correlating heating degree-days against fuel use during wintertime intervals between meter readings using this methodology. It's often the case that a right-sized heat pump will fill the bill for both heating & cooling, and provide better heating season comfort than the usual 3x oversized gas burner.

Thank you very much. I really appreciate you taking the time to answer. It seems to be draining better right now, but the water is still rising above a comfortable level. I think I will take your suggestion and eventually install a condensate pump.

 

[Dana]

Thank you very much. I really appreciate you taking the time to answer. It seems to be draining better right now, but the water is still rising above a comfortable level. I think I will take your suggestion and eventually install a condensate pump.

When you do install the pump, be sure to pack the hole with hydraulic cement. Both soil gases and water can enter via that hole otherwise. Hydraulic cement expands as it cures, creating a better seal & bond than other types of concrete/cement patch.

 

[WorthFlorida]

Being in PA, a hole in the ground as it is assumed that all it is may allow radon gas to seep into the home. In the picture there looks to be a sump pump pit. When was the home built and the age of the AC units? It probably was built with AC in the plans so the drain may go to a sump pump.

 

[RobS2244]

Being in PA, a hole in the ground as it is assumed that all it is may allow radon gas to seep into the home. In the picture there looks to be a sump pump pit. When was the home built and the age of the AC units? It probably was built with AC in the plans so the drain may go to a sump pump.


View attachment 54728

Yes, that is a sealed sump pit. It was unsealed when we purchased it, but the radon levels were high, so in addition to installing a fan/pipe, the radon mitigation contractor sealed the sump pit because it apparently is a culprit for allowing radon gas into the home. The home was built in 1997. I'm not sure how old the AC units are, but they were manufactured around 2000. Are you saying that the floor drain, which appears to be dirt, may be diverted into the sump pit?

 

[WorthFlorida]

A closer look at the pictures it does look like the hole was drilled into the concrete. Did you remove the pipe at all or only assumed it is into the ground? Is there a tile drain under the concrete floor?
If you have a compressor, open the pipe and blow air into it. At the sump pit listen for any air or run a garden hose. If it backs up immediately it is in dirt, easily flows it draining somewhere?
I had a home built in Cicero, NY in 1987 and under the basement floor was about 6 inches of stone and the floor was not attached to the walls (2x4 was used and removed) to allow any water to drain from the floor. I had to use it once when the washing machine broke full of water. There was no radon gas in that part of the state because the ground was very wet and there was alway water trickling into the pit. Your home may have a base of stone that could allow drainage. For twenty years it all seems to work without any issues but your cooling season is short. The only fear I would have is if it is directly into the ground, is radon gas entering the home? There is a trap but probably would dry out during the off season.

 

[Dana]

Yes, that is a sealed sump pit. It was unsealed when we purchased it, but the radon levels were high, so in addition to installing a fan/pipe, the radon mitigation contractor sealed the sump pit because it apparently is a culprit for allowing radon gas into the home. The home was built in 1997. I'm not sure how old the AC units are, but they were manufactured around 2000. Are you saying that the floor drain, which appears to be dirt, may be diverted into the sump pit?

With the hole drilled in the slab it's undercutting the ability of the radon fan to depressurize the slab, since when the sub-slab pressure drops it sucks basement air in through that hole. EVERY crack seam, and hole in the slab needs to be sealed up for the fan to do it's job well.

Furthermore, all the air getting sucked through that hole is bringing outdoor air at the same rate into the house & basement via whatever & wherever leaks in the building envelope happen to be. That radon fan is actively forcing outdoor air infiltration 24/365 until/unless you air-seal the slab completely. Hopefully the radon contractor caulked the seam between the slab and foundation walls everywhere, and hit all of the cracks in the slab with self-leveling polyurethane(?).

 

[WorthFlorida]

Yes, it is done 100% wrong and the suggestion from the “professional” is correct.

When the hose is connected to the disposal, a seal plug inside the disposal must be knocked out. See instructions on line on how to do it. Do get ride of the flex pipe.