Humidity Issues

[Tech13]

Had a 12.5 ton York package unit replaced with a Trane 12.5 and i am having humidity issues that i have not had before. First stage puts humidity back in the building and drops the temp at the same time.Both units have a high static blower.

[Mike19]

Did your installing contractor check airflow on the new unit on startup? Could be moving too much air which could cause humidity related issues.

Depending on what model your old York was and new Trane are, there are a few things that come to mind.

With the Trane, when you say the First Stage, do you know if the first stage opens the economizer to bring in outdoor air, or does the first stage bring on the first stage compressor?

Other thing too depending on model its common for a 12 1/2 ton York for each stage to be 6 tons, some units stage one is (I think) 4 tons and stage two is 8 tons. So the unit will come on and run for a longer time at a lower capacity which will dehumidify better.

On the Trane, your first stage may be a higher capacity, and the second stage a lower capacity. If there is a lower heat load on the building, the unit will come on, cool down and shut off, and may not run quite as continuous as the York may have.

[Tech13]

Thanks for the info,first stage brings on compressor and i think the old unit first stage was smaller tonage i will check and find out. The Trane first and second stage compressor are the same tonage.

[beenthere]

Min opening on the economizer may be too much.

[ryan79]

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[hearthman]

Does it have an economizer ?
what are your outside air conditions ?
Where is this unit installed ? office building or is it in a place where there is a lot of humidity ?

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[ryan79]

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[beenthere]

ryan79, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise, commentary or ask questions of the OP here.

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[MicahWes]

I bet is is something easy like the economizer minimum setpoint being open too wide or something. I did have an issue like this with an older Carrier last month. I was scratching my head for a while, but then I figure out someone had switched the two stages. The bottom of the evap was supposed to be #1 and the top #2, but they had reversed the contactors. Stage 1 would incorrectly operate the top half of the evaporator and all that condensate would flow downward on the warm bottom half of the evap.