Dehumidifier Verses Humidex
Does Your Home Have a Humidity Problem Like Amy’s Home?
Today, I spoke to a woman named Amy with a house near a swampy, wet area. Moisture in her home was out of control. She and her husband had just put on new siding and other expensive renovations to their home. They were researching a solution to their home’s humidity problem and had it narrowed down to a Dri-CrawlSpace® COMPACT Crawl Space Dehumidifier and a Humidex System.
I asked Amy to describe the conditions of the crawlspace and the surrounding area. She told me the yard borders a swampy area where the water frequently floods. She said the crawlspace was very moist, though there was no standing water. Windows throughout the house would often turn foggy.
From what Amy told me, I knew the entire house, not just the crawlspace, had a humidity problem. Foggy windows are a strong sign of a severe moisture problem throughout the home. Often the moisture problem occurs in the crawlspace, while air is comfortably dry on the first floor. In her situation, moisture on the first floor was condensing on the windows. This means there is a severe moisture problem in the crawlspace as well as the living space above.
Outdoor Environment Directly Affects Indoor Air Quality
In looking at the environment, we know the area is extremely damp. Air inside a home comes from the air outside. Water vapor in the air does not disappear when it enters the home. Dew point of the outside air is the same as dew point of the inside air. The only thing that changes is temperature. Colder temperatures of surfaces in the crawlspace will collect condensation. Warmer temperatures in the living space above will feel dryer (this is called relative humidity), simply because they are warmer.
Will Humidex Work for Amy’s Home?
Now, lets get back to Amy’s situation. She was trying to decide on using a Dri-CrawlSpace® Dehumidifier and a Humidex. The Humidex is a passive dehumidification solution that works by pulling air from the living space above and blowing it into the crawlspace below. For a Humidex to work, the air in the living space must be dry. In Amy’s home, with its severe moisture problem, air is humid everywhere (proof is the fog on the windows). Since there is a moisture problem throughout her home, the Humidex will simply stir around moist air. Humid air from the living space would be pumped into the crawlspace.
Dew point of the air is the temperature at which water will condense. Dew point of the air in your cold crawlspace is the same as the dew point of the air in your warm living space. In the warm part of your home, air feels dry. This air has the same absolute humidity, but because it is warmer, has a lower relative humidity. This air at a high temperature can hold its moisture, feels dryer, yet contains the same amount of absolute humidity (moisture). 
If a Humidex fan pulls that air down to your basement, the dew point does not change - because the Humidex has no dehumidifying capabilities, the actual amount of moisture in the air remains constant. As soon as that air from a Humidex hits your cold pipes, cold windows, cold walls and cold floor in your crawlspace, it will condense and water will accumulate. As this warm air from above cools, the relative humidity that you feel will change as the temperature changes.
So the answer is NO, a Humidex will not solve Amy’s humidity problem. Amy has severe humidity problems throughout her home and requires a crawlspace dehumidifier. A dehumidifier actively changes the dew point by removing water from the air.
Severe Humidity & Moisture Solution
When you have a severe moisture problem, you need to remove moisture from your home’s crawlspace. Using a commercial strength dehumidifier will pull moisture out of the home’s problem area and deposit it outside. The Dri-CrawlSpace® units we have engineered are powerful workhorses that you install, set the humidistat and automatically regulate your home’s humidity all year long.
Using the same calculations that can be found in our "How to Size a Crawlspace Dehumidifier" blog, I was able to determine Amy’s home with a 1200 square foot crawlspace, 3-4 feet high (3,600 cubic feet) and severe levels of dampness could maintain 40-50% relative humidity 98% of the time using a Dri-CrawlSpace® PLUS dehumidifier. An additional Dri-CrawlSpace® COMPACT could be helpful during extremely wet days, though not absolutely necessary. Having an additional unit can help lower electric costs by dividing the load between the two and never running either one at maximum capacity.
Concerned About Cost?
It seemed like a big part of Amy’s decision relied on price. After further investigation into the Humidex warranty, I found that the unit must be installed by a certified professional installer. Installation requires cutting holes through your floor in several places. Based on the work involved and current cost of contractors, you can bet you will pay more for a Humidex installation than your cost of a Dri-CrawlSpace® Dehumidifier. Installing a dehumidifier is easy enough for most people to do by themselves.
The other cost involved is electricity. If you are reading this, Amy, I now have the numbers for energy consumption.
| Dri-CrawlSpace® COMPACT  |
Dri-CrawlSpace® PLUS  |
|
| Efficiency Based on Electrical Consumption | ||
| Amps | 3.5 amps | 4.2 amps |
| Watts | 403 watts | 483 watts |
| Kilowatts | .403 kW | .483 kW |
| Efficiency Based on Water Removal | ||
| Kilowatts / Pint | 0.0115 kW/ppd | 0.0090 kW/ppd |
| Liters/kWhour | 1.72 L/kWh | 2.04 L/kWh |
Energy consumption for both of our Dri-CrawlSpace® dehumidifiers are well within the range of acceptable for Energy Star Compliance.
Furthermore, at the 2006 national average of 10.94 cents per kilowatt-hour, assuming the unit must run about 30% of the time (depends on your level of dampness) you would pay $10 to $15 per month to run the Dri-CrawlSpace® PLUS. The Dri-CrawlSpace® COMPACT would cost about $8 to $10 per month. The Humidex would cost less to run, but it’s just a fan - it would be a total waste of money. As most experienced consumers have come to know, "you get what you pay for". But in this case, installation cost for a Humidex, along with cutting holes for vents in your floors will easily outweigh the cost to purchase and run our energy efficient dehumidifier.
There are plenty of crawlspace exhaust fans on the market that do exactly the same thing as the Humidex. They use a humidistat to kick the fan on and off depending on humidity. Vents from the crawlspace to the first floor allow a free exchange of air. Air is exhausted from your crawlspace and replaced by air sucked down through your vents. The problem is they just don’t do anything at all to remove humidity from your home. The Humidex is just an overpriced fan. I would hate to see it happen, but if those of you with humidity problems in your home were to use a Humidex Crawlspace Fan, your going to end up wasting money on a contractor to put holes in your floors, install a vented fan and end up with a useless system installed in your home. And none of that money is refundable. Our Dri-CrawlSpace® Dehumidifier offers a 100% money back performance guarantee - if you don’t like it, get all your money back.
Air Exchange Between Crawlspace and Home Living Space
If you have a nasty crawlspace with a moisture problem, you don’t want to cut free flowing vents between your crawlspace and living space. You want to shut off your crawlspace. You want to prevent air exchange between your crawlspace and the rest of your house. Seal off the crawlspace and put a dehumidifier down there to maintain proper humidity. No matter how well you seal the crawlspace, air will always find a way up from your crawlspace, but limiting the passage will help keep moist air from entering the crawlspace and passing into your home living space.
Plus, fewer vents and openings between the living space and crawlspace, and from the crawlspace to the outside will help limit the creepy crawly critters like spiders, cockroaches and silverfish from entering your crawlspace and traveling up into your living space.
Because the crawlspace is always colder than the house above, relative humidity is always higher down there. The crawlspace is notorious for trapping moisture and growing mold. By using a crawl space dehumidifier to actively maintain humidity levels in your crawlspace, you will also regulate humidity throughout the home.
Humidex Vs Dehumidifier
I found on the Humidex website, a whole page devoted to comparing their product to what appears to be appliance grade dehumidifiers. It makes me laugh to see their product compared to something that is not even designed for a crawlspace. They talk about daily maintenance, emptying the bucket. If your dehumidifier has a bucket to empty, it has no business being in a crawlspace. Don’t be fooled by someone hyping up a crawlspace exhaust fan as a solution for major humidity problems. The bottom line is that the Humidex can only dry your home to the level of the air that is already there. If you have a moisture problem in your entire home, or live in a humid area, moving the air from one part of your home to another will do you no good.
Call 1-800-564-0667 and talk to someone who knows more about humidity and air than just about anyone you know. Our equipment specifying engineers will use the same techniques for your problems that they use everyday on commercial and industrial humidity control issues. We can talk you through a solution for your problem that we guarantee will work.
