Oily Stuff in ERVs

I visited a house a couple of days ago that was full of HVAC issues.  About 4000 square foot house with multiple systems including two poorly installed ERVs.  Summer house, so it is infrequently used.  When I opened the covers on each ERV an oily substance dripped out.  At first I thought it might have been water from uncontained condensation, but it had an oily consistency.  I mentioned it to another rater and he said he'd seen the same thing in three other systems.  The units still worked, but could it have been coming from the motors?  Anybody else seen this?  Anybody know what it is?

Thanks.  Paul

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  • Coming from the exchanger cores?  or below the motors?   Fresh air inlet side our outlet side?  Inside house air inlet/outlet side?

    • The oily stuff drips out when the cover is opened.  Unfortunately I don't have pictures.  Doesn't seem to be below the motor.  Just wanted to know if anyone else had seen this phenomenon.

      • It does make a difference where you are seeing the oily stuff.   If humidity is very high,  and there is any organic dust (skin particles,  VOC's etc) that are carried in the air stream - its possible that the oily stuff is byproduct of a mold or decomposition  of things in the air.  Moist air carries with it more than just water.  If you pulled the exchanger core out and looked at it is it perfectly clean or one side contaminated?

        I've seen oily build up above showers where the humidity condenses but mold itself hasn't started to grow...   fungi growth can start off looking like an oily surface -- location in the ERV is critical to determine the root cause.  Without that - its just guessing.

  • Got pics - where is it pulling air from in the house (stove area?) Where do you see it in the unit - sidewalls, filters...

    • There are two different ERVs both with the issue.  Air on the return side is coming from the return duct and being pushed back into the return duct.  There is a fresh air feed from the outside.  No stove connection and the filters seem clear.

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