Dehmudification of Basement Level Condo

[jessdogg]

Hello,

I live in a basement level condominium in New England where humidity is an issue in the Spring & Summer months and where the indoor temperature is relatively constant as a result of being underground. That being the case, I don't often need my air conditioner to be on and so have no way of controling the humidity without overcooling my apartment.

A whole house dehumidifier attached to my existing central HVAC had been suggested as a possible solution by one vendor, but because space is at a minimum where the HVAC unit is currently installed, I would be required to build a soffit to connect the dehumidifier or duct it in from another nearby closet which would not be very visually appealing. I've also been told that this type of system is capable of generating a significant amount of heat that would be unwanted.

As an alternative, another vendor proposed the following solution. I am not an HVAC expert and am fearful that the two stage system being suggested would still require the AC to be on in order to lower the humidity in my unit. Since I do not need the AC very often, I wonder if I will still need to over cool my home in order to get the proper humidity levels.

"We will provide and install one new R-410a based two speed high efficiency out door air conditioning condenser. This will allow the existing air handler to run at a lower speed more often without over cooling while allowing the system adequate time to dehumidify the space. We will connect to the existing indoor air handler servicing the basement area. We will properly flush and test the refrigeration piping. We will provide and install one new digital two stage thermostat. We will reconnect to the existing wiring and piping. Any upgrades required will be an additional cost."

I would really like to get some opinions from the community on what the best approach is given my situation. What do you think?

Thank you!
Jess Dogg

[teddy bear]

Welcome to a mixed crowd! There some here who will say that a two speed a/c will do the job. And if it does not, than you oversized it.
I am from the very small other crowd that says, no cooling load, no real dehumidification, unless you have a dehumidifier. You need a device that can remove 3-5 gals of moisture per day without any cooling. A good dehumidfier will not generate excess heat. A little warmth is desireable in a cool basement, after all you are cool enough but not dry enough. Look at the Ultra-Aire 70H compact ductable unit. It is very efficient, reliable and reasonably quiet. It is one of the more efficient dehus of that size. The manufacturer is the pioneer of the ducted dehu. Beside I have worked for them for many years. Now semi-retired and able to lay and wait for posters with humidity problems.
Regards TB

[sneezer]

TB is right, and your fear is justified. A very well-designed air conditioning system will reduce the need for dehumidification substantially. When it is too humid and you are cool or at the right temperature, you need a dehumidifier.

TB, why aren’t HVAC systems installed with reheat coils for situations like this?

[teddy bear]

TB is right, and your fear is justified. A very well-designed air conditioning system will reduce the need for dehumidification substantially. When it is too humid and you are cool or at the right temperature, you need a dehumidifier.

TB, why aren’t HVAC systems installed with reheat coils for situations like this?

The reason that reheat coils are not used is that they cost alot more money to operate. Imagine a 1.5 ton dehumidifier removing moisture at a 1-2 lbs. per kw. At the end of the dehumdifying cycle, you have the a/c coil with 2 lbs. of water hanging on the coil. The 2 lbs. of moisture on the coil slowly evaporates back into the space, which raises the indoor humidity above the dehumidistat set point. This starts the drying cycle all over again. A ducted dehumidifier properly sized, removes 3-4 lbs. per kw and holds only a fraction of a lb. of moisture on its coil. Real dehus are more practical and operate for fraction of the cost.
Regards TB

[sneezer]

Thanks, that clears a things up a lot.