P-Trap Distance from air handler


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Old 12-13-22, 09:17 AM
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P-Trap Distance from air handler

Our upstairs heat pump air handler is in the attic. The p-trap is about 6 inches from the handle, goes horizontal around the chimney (probably 6'), then a vertical drop to the crawlspace (guess 20'), then probably another 20' horizontal, to 3' vertical into the sump pump.

Haven't had any issues so far and the p-trap is covered in batts but I've never liked the idea of having standing water up there in the winter. Is it a problem if I move the p-trap to right before the 3' vertical drop before the sump? It would be a long ways from the air handler at that point so wanted to check if there was a distance requirement.
Would replace the section up in the attic with a Tee for periodic cleaning.
 
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Old 12-13-22, 02:56 PM
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The trap in an A/C air handler is needed because when the blower runs it can cause a suction on the drain line which won't allow it to drain. The drain pan would fill up and overflow.
 
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Old 12-13-22, 11:43 AM
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No need to move the trap.... just blow it out at the end of the season.
 
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Old 12-13-22, 12:12 PM
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Thanks. That's a valid option for sure. Due to the attic access, sucking it out from the crawlspace would be easier though still a pain to get the vac down there. Just trying to avoid something that relies on me remembering or not procrastinating.

 
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Old 12-13-22, 12:33 PM
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I've never had an attic p-trap freeze/break/crack on an A/C only system. I think by the time the really cold air sets in most of the water has evaporated. What's left isn't enough to cause damage.

I'm not really sure what would happen moving the trap a distance from the air handler.
 
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Old 12-13-22, 12:37 PM
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It's probably just worrying and making work for nothing. I would be surprised if there isn't enough heat lost through the ceiling to keep the trap above freezing most of the time anyways. I'll table this for awhile and stick with just cleaning/sucking the drain out late fall.
 
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Old 12-13-22, 01:48 PM
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If the drain just (eventually) runs to an open sump, do you even need a trap? I suppose code calls for it, but as a practical matter, if the sump is open, there's no way for sewer gases to flow up the drain into the attic.
 
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Old 12-13-22, 05:33 PM
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Makes sense, Pete, thanks!
 
 

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