New York Excessive Condensation

Discussion in 'Maintenance and Troubleshooting' started by geek, Jul 22, 2019.

  1. geek

    geek New Member

    I have a 4 ton Waterfurnace Envision split system with the blower located in the attic and the heat pump in the basement installed in 2012, running without incident since. Every time I've changed the filter, the condensate pan underneath the blower has been completely dry. The weather this past weekend in the Northeast was excessively hot and humid and apparently the water sensor in the condensate pan under the blower unit was triggered on Saturday because of significant water accumulation. I opened up the blower unit and the pan inside underneath the coil was full as well. I drained both pans (probably 3-6 gallons). I checked the drain line which must've been clogged (banged it a little bit), because I drained through the side plugged which is higher than the drain line. but I didn't auger the line but from what I could tell from the drain end in the basement was that no water was coming through it. This got the system back up and running Saturday evening.

    Sunday morning, I went to check on it again. Water was draining coming through the end in the basement, but there was additional accumulation in both condensate pans (inside pan under the coils and outside pan), probably 1-2 gallons, but the system was otherwise working. I removed the water. The water in the inside pan is about 0.5" high but below the drain line. The cold air wasn't super cold, but it was able to keep up with the 95+ heat througout the day. I checked again this morning (Monday) and system was working but there was still additional accumulation of about 1-2 gallons, which I removed again.

    I checked the loop EWT & LWT and they are generally in the high 70s (I haven't been running a log prior to the issue). When the system is running the temps are usually about 4 degrees apart, but when it stops, it looks like the EWT can actually be higher than the LWT but I thought that might be something wrong with my measuring technique (or not), but I thought it was worth mentioning.

    Also, I've never had the loop pressure checked or had the system otherwise maintained since installation, something I probably should get done now, but I thought it would make sense to do some diagnosing first.

    I assume this condensation is not normal even in high heat. Any suggestions of what might be causing it or what I should inspect?
  2. geoxne

    geoxne Active Member Forum Leader

    "It's not the heat it's the humidity." Your equipment surface temperatures are below the dew point of your attic air. This equals condensation and is not uncommon under these adverse conditions. That is why a drain pan is installed per code under the attic airhandler.

    Keep your eye on it and see if the situation improves under normal conditions. Clean and flush all condensation traps and lines at least once a year or if required twice a year at the beginning and end of your AC season. All kinds of stuff likes to grow in water. Over time it can become a thick gelatinous slime that can clog traps and pipes. Then in the heating season when it dries out it becomes a hard skin like film that clogs the traps and drains.

    Remedies in order of ease and cost of implementation. You decide how far you want to go.
    1) Keep your condensation lines clean. Make sure the airhandler is pitched towards the drain outlet.
    2) Consider a drain on your overflow pan tied to condensation pipe (a pan full of water is adding to the humidity problem) or an overflow switch that will stop AC operation to prevent pan overflow.
    3) Identify the actual surfaces that are "sweating" ie; ducts, air handler sheet metal, refrigerant lineset, even condensation lines etc. and insulate them including vapor barrier or closed cell using the appropriate material for that surface.
    4) Bring the AC equipment and ducting inside the buildings insulation envelope especially in a humid climate. Your system will work more efficiently if it doesn't have to combat the temperature extremes in a vented attic. (See below)

    Number 4 is a big one to swallow but is the final solution and has so many advantages and I strongly suggest it on new construction projects.
    Attic airhandler installations in unconditioned attics has been the standard for a long time. For many years the building codes have required vented attics. In a humid climate all this does is let the humidity in. In my coastal community this means fog (100% RH) quite often. Unless special measures are taken the AC equipment is dripping to the point that you would think it is raining in the attic.
    So, the only exception to a vented attic in the code is if the attic is insulated directly under the roof deck (no airspace). This can be accomplished with either closed cell spray foam (exposed foam will require a fire retardant) or a structural foam roof deck.

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