Odd your level went up. Maybe you have attic air getting in to your house? Get it through the roof and keep measuring.
The problem we all face is the unknowns. The entire system is assuming there is a path for the gas saturated air can be pulled. But also, there has to be replacement air. Otherwise it's like placing your hand over the end of your shop vac.
I saw a New Jersey report on failed systems and there was a lot of detail on how they accessed suction. A potential experiment; 1) see/feel how much air is exhausting at the discharge in attic. 2) If you were to place your fan on to short pc of pipe a your cored hole, you can see if the hole is allowing air to be pulled, loses compared to attic level. If you slab is sealed to damp clay, you may not pull much of anything. In any case, in this new Jersey case, they drilled several 1/2 holes around the slab to see how the draw varied.
The problem we all face is the unknowns. The entire system is assuming there is a path for the gas saturated air can be pulled. But also, there has to be replacement air. Otherwise it's like placing your hand over the end of your shop vac.
I saw a New Jersey report on failed systems and there was a lot of detail on how they accessed suction. A potential experiment; 1) see/feel how much air is exhausting at the discharge in attic. 2) If you were to place your fan on to short pc of pipe a your cored hole, you can see if the hole is allowing air to be pulled, loses compared to attic level. If you slab is sealed to damp clay, you may not pull much of anything. In any case, in this new Jersey case, they drilled several 1/2 holes around the slab to see how the draw varied.
I have the meter in the basement to see what it is down there.