Plumbing – How to one test a sewage ejector pump

What is probably going on is that your neighbors' weeping tile systems are draining into their sumps, which are then pumped out because they're below grade and there isn't a storm sewer at a lower grade that can be drained into. The weeping tile exists to direct water that soaks into the ground away from your house, instead of letting it collect against your foundation walls and leach through, or worse, freeze and heave against your house in the winter. Depending on your soil type, rainwater can stick around for months in the soil, and you may also have an aquifer or water table nearby that provides a relatively steady source of groundwater into the soil.

So, what I'm saying is that depending on how much rain you've had recently (as in the past few months) it's perfectly normal for your neighbors' sumps to still be filling. Depending on the land grade, it may also be normal that your sump isn't yet filling while your neighbors' are (water will soak more into land that is downhill). Just make sure your sump pump is in good working order and don't worry about it any more, unless you start to see damp areas along the walls or floor of your basement; these would generally indicate blocked, crushed or missing weeping tile.

I have a setup similar to yours and the radon installers put a foam sheet over a hole in my sump cover, almost like a thin sheet of packing foam. This is almost airtight but allows some suction for the fan. You could terminate the drain line over a small hole that was covered with foam or paper such that the the air would be sealed in, but in the case you get water from the heater it would drip through it. You could also put a check valve in the pvc line from the heater but it would have to be loose so a trickle of water would trigger it. A trap would dry out, although the HVAC trap probably dries out during the winter anyway....but the suction from the fan should override that small opening.