I'm considering getting a whole house humidifier for my two-story house (with finished basement). I had the air handler replaced this past fall and I'm curious if the new air handler (Goodman) is not removing humidity from the air as well as the old unit (28 year old GE). Just this year, I've noticed a few of the ducts sweating quite a bit in the basement, so much so that they are staining the ceiling tiles. I'm not sure if this is because the air handler isn't doing a good job at removing the humidity, or if it is cooling so much more than the old unit. Regardless, I suppose the only feasible solution is to install a dehumidifier, but I don't want to pay a fortune for one (< $1,000 preferably). Can someone address my humidity question and/or recommend a reliable economical dehumidifier? By the way, the humidity is about 62%, which is way too high. I would also consider buying a standalone unit for $200-$300 and possibly placing it in the basement (if that makes sense to do).

 

I just have a couple hundred dollar unit in the basement and it's perfectly adequate, I think most people only need something like that - it's uncommon situations which require a big gun unit.

 

Just to be clear, it is not only humid in the basement, but on the main and upper floors as well (over 60%). Would putting the dehumidifier in the basement next to the return vent be the best thing to do? How much have you been able to lower your humidity using a portable unit (not just in the basement, but the whole house)?

 

I set the dehumidifier at 35% and leave it alone. It sits in the utility room in the basement and the furnace vent is open in that room so the air is distributed to the rest of the house pretty well as long as the furnace fan is running, meaning the AC is running. If the windows are open, it can't keep up as it's not big enough to dehumidify that quantity of air.

 

Dehumidifiers were never designed to maintain 35% rh; the lower the humidity is, the less efficiently they operate. 50% is fine for the summer.

You should only need a dehumidifier when it's not warm enough for the a/c to run much.

Causes of high humidity:

- Blower speed set too high (on the better air handlers, the blower speed can be automatically reduced when the humidity exceeds a certain threshold)
- High air leakage
- A/C Oversized

 

I'm assuming the unit has a single speed fan because it was replaced under my home warranty and they typically use the most basic models of equipment. Even if it is fixed speed, shouldn't the motor itself have multiple wires so I can hard wire it to a lower speed? For example, if it is connected to high for cooling, can't I just switch the wire to medium high (if such a wire exists)? Don't most air handlers including single speed versions use a slower speed for heat and a higher speed for cooling?

 

Even the most basic air handlers have multi-speed blowers. (3 speeds is the minimum)

Setting it too low can cause damage; in most applications the highest speed is the correct setting for cooling. (it depends on the size of the air handler relative to the capacity of the outdoor unit, as well as the duct system)

Too much airflow is the least likely cause of high humidity.

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Be sure to use exhaust fans when cooking and showering.

Furnaces are like that.

Some air handlers may use the same speed for both heating and cooling.

 

Any basment in a green grass state will benefit from a dehumidifier! Even in the summer. With RH as high as you have on three floors you need to get a good unit like a Santa fe! There not cheap but cheaper to run than a couple of the off the shelf units running together. It's serviceable. They have Merv 11 filtration. Plus remove about twice the RH.

 

^I look those up - very pricey.

When there's a high cooling load, the system should take care of the humidity.

When it's cool but humid outside, a dehumidifier is needed especially in older basements.

 

When there's a high cooling load, the system should take care of the humidity.

Not in green grass states were you have all the moisture from the ground seeping into the basements.

 

If your system is running pretty steady on a very warm/hot days, and the humidity is still high, then the blower was not set up right. The blower should be moving around 400 cfm per ton. So if you have a 2 ton system, blower should be set around 800 cfm to remove the humidity.

 

A good dehumidifier for the whole house is the Danby ddr7009ree. It pulls the moisture out of the air real fast and gets rid of even very musty smells. Its also made in the USA. See http://www.best70pintdehumidifiers.com

 

I live in Northern Virigina, the basement is mostly below ground, and there is not musty smell. It is quite comfortable actually. The only problem is that sweating duct, which began sweating once the new air handler was installed. I removed the ceiling tiles and it has not sweated since. I plan on wrapping it in duct insulation and reinstalling the tiles. Otherwise, everything seems to be ok. Do I need to do anything else (e.g. adjust fan speed)?

 

Alex that is not a whole house dehumidifier. It's a stand alone unit. Whole house units get installed into the duct and many have outside air capabilitys.