# need ideas to lower humidity



## Eaglei (Aug 1, 2012)

I need some help with controlling the humidity in a dance studio . I already replaced the hard wood floors and planed all the interior doors due to humidity .So anyway I have a new gas hot air furnace with a/c coil and 5 ton compressor . What can be done with the HVAC unit or a separate unit to control the humidity . I don't want anything that has to be emptied manually and I need it to run whenever the humidity levels are beyond a predetermined level . The R.H. is not extreme by any measure but does fluctuate depending on the time of year and whenever theres a class full of student dancers .The floor area is 1200 sq ft. if that helps .


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## TimelessQuality (Sep 23, 2007)

Dehumidifier ?


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## TimberlineMD (Jan 15, 2008)

You need a load calc done. A 5 ton AC for 1200 sf is way oversized, I'd bet.

The unit needs to be sized so that it runs continuously when a class is in session and most of the time when not.


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## mbryan (Dec 6, 2010)

Air conditioners work as dehumidifiers so anytime its working its dehumidifying. What kinda readings are you getting inside, outside and when there isn't class in session?


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## Eaglei (Aug 1, 2012)

TimberlineMD said:


> You need a load calc done. A 5 ton AC for 1200 sf is way oversized, I'd bet.
> 
> The unit needs to be sized so that it runs continuously when a class is in session and most of the time when not.


The reason it's oversized is because the original 3 ton unit could'nt keep up when there was a full class of dancers . The ceilings range from 8-12 ft high .


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## MarkJames (Nov 25, 2012)

I'd first try a dehumidifier with a drain hose. If there's no drain nearby, get one with a reservoir pump & tubing. Run the tubing same as from an AC condensate pump (up to ceiling, looped, then across to wherever (drain, exterior, etc).

Or use one in combo with a separate condensate pump.


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## Eaglei (Aug 1, 2012)

mbryan said:


> Air conditioners work as dehumidifiers so anytime its working its dehumidifying. What kinda readings are you getting inside, outside and when there isn't class in session?


The humidity gets out of control between the heating and cooling seasons and this is one of the causes for the floor cuping and doors swelling . So this is why im thinking I need a dehumidifier to run when called for .This is also a post sandy building with a slab on grade . I took R.H. readings this morning and it showed 70% inside and outside was 82% R.H..The inside temp was 68 deg and 80 outside . I also took readings on the flooring and they were'nt to bad , average was 8.5% . We have had a very rainy May and June so im sure this only made it worse . I understand the a/c units help to control the R.H. but only when it's running .


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## CarpenterSFO (Dec 12, 2012)

Are the floors actually cupping convex side up? This probably has to do with the weather here being so simple, but I've never worried about humidity above a floor, only below. Interesting.


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## MarkJames (Nov 25, 2012)

CarpenterSFO said:


> Are the floors actually cupping convex side up? This probably has to do with the weather here being so simple, but I've never worried about humidity above a floor, only below. Interesting.


Good point. If so, there's moisture from the slab. Uh oh.


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## Eaglei (Aug 1, 2012)

CarpenterSFO said:


> Are the floors actually cupping convex side up? This probably has to do with the weather here being so simple, but I've never worried about humidity above a floor, only below. Interesting.


Yea there is an issue with the slab so thats why I need a dehumidifier . Cupping , when the outter edges of the plank curve upward .Lately I feel like im living in a rain forest .I'm meeting with my HVAC guy tomorrow to see what he can do .


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## PPRI (Oct 9, 2010)

Your hvac contractor should be able to help you out. I'd replace the blower and control panel in the furnace and install an ECM blower. Then run a jumper for a humidistat. 5 ton is a little big for this setup but until the new modulating compressors come out this fall that's what you will have to work with. At least your coil will be plenty cold. This setup will let you set the RH you want and the unit will turn air slowly over a cold coil in order to dehumidify without lowering the temperature. It is also a lot nicer as an interior unit than a dehumidifier because it won't generate so much heat.


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## CarpenterSFO (Dec 12, 2012)

Eaglei said:


> Yea there is an issue with the slab so thats why I need a dehumidifier . Cupping , when the outter edges of the plank curve upward .Lately I feel like im living in a rain forest .I'm meeting with my HVAC guy tomorrow to see what he can do .


I don't think you can solve a slab moisture problem by dehumidifying the air above.


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## mbryan (Dec 6, 2010)

You have a constant 68 degrees and 70%RH in there? That is crazy humid...


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## beenthere (Mar 5, 2009)

Eaglei said:


> The humidity gets out of control between the heating and cooling seasons and this is one of the causes for the floor cuping and doors swelling . So this is why im thinking I need a dehumidifier to run when called for .This is also a post sandy building with a slab on grade . I took R.H. readings this morning and it showed 70% inside and outside was 82% R.H..The inside temp was 68 deg and 80 outside . I also took readings on the flooring and they were'nt to bad , average was 8.5% . We have had a very rainy May and June so im sure this only made it worse . I understand the a/c units help to control the R.H. but only when it's running .



Get a ventilating whole area dehumidifier. Sized at 105 pint or more a day.

That way you get the ventilation you need for the people, and dehumidified air.

Dance studios go from almost no load, to high load in less then 30 minutes at times. And people praticing dancing put off a lot of moisture. 

A 4 ton may have been the size you really needed. But many contractors won't bother to do a load calc to find out, they just put in the biggest A/C they can fit.


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## CompleteW&D (May 28, 2011)

beenthere said:


> Get a ventilating whole area dehumidifier. Sized at 105 pint or more a day.
> 
> That way you get the ventilation you need for the people, and dehumidified air.
> 
> ...


GREAT advice.... :thumbsup:



> But many contractors won't bother to do a load calc to find out, they just put in the biggest A/C they can fit.


Man, I saw that ALL the time when I sold residential HVAC. I ALWAYS did a load calc and properly sized equipment.

But your situation is quite a bit different than a residence. I do agree that a 5 ton unit is very likely WAY too big. It comes on and satisfies the thermostat before it can run long enough to pull down the humidity. 

Even after doing a proper load calc, I would think a variable speed blower would help out as well. They tend to dehumidify better because at the lower speed, the coil gets colder which gives you maximum dehumidification. 

Another thing I might check, is where the supply and return registers are in relation to the thermostat. If your t-stat is right near a supply and not the main return, that can lead to big time performance problems. Get maximum distance between your supply registers and a main return and put the t-stat right back by the air handler, which will also help balance out the systems performance.

But, I still think a 5 ton unit is too big....


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## Eaglei (Aug 1, 2012)

I'd have to say that yea a 5-ton unit is normally to big a unit for this sized area . Originally there was a 3-ton unit that would never cycle off in the hottest weather and a class full of dancers . So this is how the 5-ton unit came about . It does'nt short cycle when theres a class full and the front entrance door is being open and shut all day long .I was looking at a 65 pt. dehumidifier by honeywell that says it will do an area up to 1800 sq. ft., I have 1200sq. ft. Beenthere recommended the 105 pt. unit but that may be a little to big . I'll see what my HVAC guy says . Anyway thanks for all the suggestions .


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## beenthere (Mar 5, 2009)

That little Honeywell unit is rated at 1800 sq ft for a normal house. Not for a area full of dances sweating. 

About how many dancers on average are in the place at one time.


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## mbryan (Dec 6, 2010)

There is tons of difference in dehu's too. The conventional refrigerant will not work nearly as well as an LGR (low grain refrigerant). Make sure your looking at commercial units not what Home Depot or Walmart sell. A commercial carpet cleaning type place will be able to help you to get a commercial unit that will perform much better than a homeowner unit. Take some temp and RH readings into them and they should be able to help with what you want. Most of my work is doing water restoration so can't really recommend a size to you... 

Could also contact a restoration company and see about renting one to try out different units before purchasing one too.


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## beenthere (Mar 5, 2009)

What are you referring to, for low grain refrigerant?


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## DuMass (Feb 6, 2008)

Just a thought, but since you're saying the system is apparently already oversized, why not utilize hot gas reheat and variable speed/VAV like they will sometimes do for conference rooms where the occupancy can go from empty to full capacity in just a few minutes. An overall installation, operating and maintenance cost comparison to a full commercial dehumidifier system might be something for your HVAC Co to look into.


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