Stainless Steel Sink Condensation

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jrob4267

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I have a condensation problem under my large (32”x20”) single bowl kitchen sink. There is a garbage disposal connected to this sink as well. I live in southern NJ where it is typically humid in the summer. I also have central air condition that we run almost non-stop throughout the summer months. We renovated the entire house approximately 2 years ago, including a full kitchen renovation and installed new natural gas heat and central air unit for the entire house.

My suspicion for the cause of the condensation is that when the HVAC contractor placed the register in the ceiling in the kitchen he located it directly above the sink so there is cold air constantly blowing on the sink and I’m sure the sink temp is above the air temp under the sink in the cabinet. Therefore I get condensation, or at least that’s my guess.

I have read about others who have condensation issues but I don’t know if the typical fix (insulating under the sink) would remedy the problem since I know that with the AC blowing directly on the sink it will still condense and then the insulation will get wet and be a breeding ground for mold.

Is my only solution to move the heat/ac register or at the very least redirect it away from the sink? I am still considering insulating the sink once I get the condensation problem fixed.

If there could be another cause or other options please let me know. Thank you
 

GL77

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Can that A/C vent be completely closed off for a day to see if it makes a difference?
 

Jadnashua

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Is the issue with the inside or outside of the sink or both?

It is not uncommon for the a/c system to be oversized which does not produce optimum comfort in the house…when using a/c, both humidity control and temperature control are best…if the a/c system is oversized, you can get temperature control, but humidity control can be an issue. Ideally, on a hot design day, the a/c system would literally have the compressor is running constantly. You only remove moisture when the compressor is running or the coil is cool which doesn’t last long after it turns off.

You might want to get a relative humidity meter and see what you’re working with.

Insulating the outside of the SS bowl has advantages other than helping with condensation…it will make it quieter, too.

You may be able to change the grill to one that diffuses the air flow better rather than directing it onto the sink below.
 

Reach4

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Temporarily, try leaving the cabinet doors open some.

I also wonder if there could be a break in your vapor barrier, and the hot humid air is leaking into that area.

A hygrometer, especially one that reads in dew point, could be useful. If the dew point under the sink is higher than the dew point in the room, that would point to outside air leaking in, OR there is a water leak adding moisture. OK, another possibility is that higher RH air is coming up from the basement.

https://iridl.ldeo.columbia.edu/dochelp/QA/Basic/dewpoint.html tells how to calculate dew point, knowing relative humidity (RH) and temperature. But if your gadget can display dew point itself, that is handy.
 
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jrob4267

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Temporarily, try leaving the cabinet doors open some.

I also wonder if there could be a break in your vapor barrier, and the hot humid air is leaking into that area.

A hygrometer, especially one that reads in dew point, could be useful. If the dew point under the sink is higher than the dew point in the room, that would point to outside air leaking in, OR there is a water leak adding moisture. OK, another possibility is that higher RH air is coming up from the basement.

https://iridl.ldeo.columbia.edu/dochelp/QA/Basic/dewpoint.html tells how to calculate dew point, knowing relative humidity (RH) and temperature. But if your gadget can display dew point itself, that is handy.

Question. If I take a dew point reading with the condensation problem not being fixed I will get a false reading, correct? Also I don’t not have a basement and the crawlspace is very dry. My thermostat measures humidity and it runs usually in the 60-70% range. Don’t know if that is good or bad.

I have purchased a register deflector and will install that to see if that helps with the amount of condensation. Will report back.
 

jrob4267

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Is the issue with the inside or outside of the sink or both?

It is not uncommon for the a/c system to be oversized which does not produce optimum comfort in the house…when using a/c, both humidity control and temperature control are best…if the a/c system is oversized, you can get temperature control, but humidity control can be an issue. Ideally, on a hot design day, the a/c system would literally have the compressor is running constantly. You only remove moisture when the compressor is running or the coil is cool which doesn’t last long after it turns off.

You might want to get a relative humidity meter and see what you’re working with.

Insulating the outside of the SS bowl has advantages other than helping with condensation…it will make it quieter, too.

You may be able to change the grill to one that diffuses the air flow better rather than directing it onto the sink below.

The condensation is on the outside of the sink only and therefore the inside of the cabinet is wet.

One of my questions was that if i do nothing other than insulating the outside of the sink, is it possible that the sink will continue to condense and form water droplets on the outside of sink, under the insulation and still cause mold? Or will insulating the sink in a particular way stop the condensation all together?

Also, what is the best way to insulate the sink in this situation? I don’t want to use spray foam and have to remove it because of mold growing in between the outside of sink and foam insulation layer.
 

Reach4

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Question. If I take a dew point reading with the condensation problem not being fixed I will get a false reading, correct? Also I don’t not have a basement and the crawlspace is very dry. My thermostat measures humidity and it runs usually in the 60-70% range. Don’t know if that is good or bad.
I don't see why you would be getting a false reading.

I suspect you are talking about a humidity indicator in your thermostat. Try a portable unit.


R. Humidity in the 40 to 55% range is good for people. There are various thoughts. Stuff likes lower humidity than people, but people is what is more important. https://www.centralhtg.com/blog/managing-home-humidity-for-maximum-comfort
 

GL77

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Condensation forms when the warm moist air comes in contact with the cold steel, so if the insulation covers the sink completely, you shouldn't get condensation on the sink. I've never insulated a sink, so I don't know how practical it is to get it covered completely. Maybe a multi-pronged approach is best, try to redirect the cold air away from the sink and also insulate the sink.

I once dumped out the freezer's ice bucket in my ss sink, didn't think about condensation until I opened the cabinet doors for something and then I realized what I'd done, water was dripping off the underside of the ice cold sink. It definitely can happen if the sink gets cold enough.
 
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