Dehumidifier is Good, Conditioned Air is Better and
The Best is Both!
A Crawl Space Dehumidifier is Good
A good quality
crawl space dehumidifier that is sized properly for the crawl space will
make the difference between one that gets the job done efficiently and one that
does not, but makes you feel good until you get the electric bill.
Not all crawl space dehumidifiers are created to do the same job. Yes they are made
to dehumidify but all have different capabilities and when you have one
designed for a bedroom trying to control an entire crawl space you will have
failure. Keep in mind its not about the price, meaning more expensive is
better. The key to proper dehumidification is proper air flow and proper
water removal, in that order. If you can't get the moist air to the
crawl space dehumidifier it does not matter how much water it removes. Pints per
kilowatt hour (P/kWh) or Liters per kilowatt hour (L/kWh) will determine how
efficient the unit is.
If
you are not sure what size crawl space dehumidifier you need give us a call and we can
help you size one. 877.379.7658
Conditioned Air is Better-
Depending on your climate your heating and cooling unit can control the
moisture in your crawl space once you open supply and return; this method is
allowed by the building code (IRC R409.5.5 conditioned space). This method is
better than just a crawl space dehumidifier for a couple of reasons:
- You already own the equipment
- This method will make the home more comfortable in the winter months
- Your home gains some geothermal benefits from the naturally cooler
temperatures in the crawl space during the summer months
- Your home will be more energy efficient
In order for this method to work in your favor on all points, the
exterior foundation walls will need to be insulated according to your local
energy code (usually 1" R-5 rigid in the south and 2" R-10 in the north).
Remember the space will be clean and free of the problems you currently
have-
The Best is Both
Just like not all basements need a dehumidifier (because they have
conditioned air), not all crawl spaces need one- but most do. If you live in a
climate where your dew point is above 55 degrees I can tell you that you will
most likely need a crawl space dehumidifier. Here's why- If your temperature equals the dew
point then you will have 100% relative humidity, which is really bad. So the
higher the dew point the better chance you have of maintaining high humidity.
Here is an example; we had two crawl spaces just outside of Greensboro, NC and
both had 60 F with 83% humidity. Inside the house it was 72 F and 55% humidity.
The house was in good shape, but the crawl was not (in that environment a mold
problem could start in as little as 9 days). The crawl space was conditioned
with air from the home via the A/C. The outside dew point was 67 F and the A/C
was able to get that down to 55 F inside the home. The air in the home is the
exact same air in the crawl space with the exception of the temperature. Here's
where it gets tricky, when you cool air it becomes more dense as you get closer
to the dew point. Once the temperature reaches the dew point the moisture leaves
the air and condensates or settles on the cooler parts of your home, via 100%
humidity. If the humidity in the home was at 40% the crawl space would be at 55%
under this same scenario. As you can see the A/C could not get the moisture
content down far enough by itself to keep the threat of mold growth out of the
crawl space. The outside dew point directly affects the success of the A/C
unit's success. In a different part of the country, like Michigan, (at the same
time) where the outside dew point is lower year round there is less of an impact
on whether the A/C can successfully dehumidify the crawl space. With the house
at 72 F the humidity would be 38% with a dew point outside being 44 F (instead
of 67 F) therefore the crawl space would be 55% at the same 60 F. If this is
confusing, I apologize. There are two tools that will tell you what you will
need if you don't know or don't want to guess, a hygrometer
like this one and a dew point
calculator like this one. You can use the
hygrometer to keep an eye on the humidity in the crawl space with its wireless
remote and use the dew point calculator to know how to adjust the crawl space
environment with either dehumidification or a raise in temperature.
Of course we are always available
to answer your questions.
The Solution!
The best advice I can give you is to not use a crawl space dehumidifier that is the
improper size or quality and expect it to protect the crawl space from high
moisture and allergens like Mold and mildew. There is not one fix for all crawl
spaces because there are many factors that play into the solution. I can tell
you this for sure, if your crawl space dehumidifier is running all the time- it is
not working, and you are paying way to much
in your electric bill. If the A/C can not dehumidify the crawl space on its own,
you are way ahead if you spend a little more up front and get a crawl space
dehumidifier
that is sized properly because it will keep the humidity down and not run as
much, which means lower electrical costs and a longer life. If you do end up with
a mold problem it could cost you $4000 - $8000 or more to clean up, while one
quality crawl space dehumidifier that is sized properly can prevent it.
We would be glad to help you size a crawl space dehumidifier for your crawl space, even
if you don't buy it from us! 877.379.7658 it only takes a few minutes. Have your
square foot & crawl space height information available when you call.
