New home owner here. When I bought my home, they did the radon test and found the levels high, so a radon fan was installed. I recently investigated the radon fan setup, and discovered that it seems to be coupled with a submersible pump in the basement. Is this normal? I'm concerned that running the submersible pump is using a lot of energy (it's a 9.7 amp/115 volt pump, which equals ~1115 watts by my calculations).

A little more info: it seems that there are two PVC pipes into the sump area. One is connected to the submersible sump pump, and the other is presumably connected to the heat pump outside.

Also, there is a noticeable level of water in the bottom of the sump. Is this normal? The sump is sealed, but is NOT air-tight. Is this normal? The manometer pressure value indicates 1.6, if that means anything to anyone.

What is the function of the submersible pump?

  • How is this pump coupled to the fan? Mechanically, by a shaft? Are they energized together electrically, but mechanically independent? Dec 30, 2017 at 5:23
  • other is presumably connected to the heat pump ... do not presume, find out for sure how everything is connected and update your question. it is pointless for anyone here to be guessing.
    – jsotola
    Dec 30, 2017 at 6:19

2 Answers 2


That thing is called a sump pump. It has nothing to do with your radon or your heat pump. It has one purpose, removing groundwater from your basement. Without it, your basement may eventually flood.

The water at the bottom of the sump is normal. This is what primes the pump. Many pumps rely on hydraulic lock (the incompressibility of water) to function aka to "prime"... And also need the water as a coolant and lubricant. So don't be surprised when you find a pump that Does Not Like running dry.


The fan takes a relatively small amount of electricity and the sump pump has a very short duty cycle. I see no problem with them sharing a circuit. On the two pipes that enter the sump basin, One does indeed connect to the pump for discharge the other is a vent and ultimately exits through the roof as part of the overall vent system. It is normal for some water to remain in the bottom of the basin at all times. The pump is not able to suck up all of it. The basin lid is not expected to be absolutely air tight against any significant pressure. It is however expected to be tight enough to prevent vapors/odors from entering the living space. Your sump picks up all the drainage from basement located plumbing fixtures. Their drains are piped under the floor and into the basin. Using a float switch, when the water reaches a preset level withing the basin the pump is cycled on. When the water level drops below another preset level the pump is cycled off.

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