OT: Who's the scientist here.....

Maybe it's broken?

;^)

Martin

I doubt it. its sucking water like crazy out of the air.

you would think the opposite...

It shouldn't make it stuffy but it will make the room warmer.

Dehumidifier is sort of like having a room A/C unit all inside your house. The front (evaporator coil) cools the air as it enters it and the moisture condenses on it. Then air passes over the condenser coils where the air warms back up.

In the ideal world, the air entering and exiting it would be almost the same temperature. But since both the compressor and the fan motor generate extra heat, that makes the air exiting warmer than the air entering it.

That is the explanation in laymans terms.

Window A/C unit (or a portable A/C) would be a much better choice. They dehumidify the air and exhaust the warm air on the outside.

Peteski

snipped-for-privacy@earthlink.net wrote in news:1156476630.732680.110680 @b28g2000cwb.googlegroups.com:

And putting it where? Without an external exhaust, the moisture can just end up back in the (now warmer) air.

cd

i like ganga, mon.

What Pete says is true. The dehumidifier that I have in my basement (where an AC is not an option) warms up the room during the summer, so I mounted a bathroom vent-fan to help suck out the excess heat. It works quite well. Regards,

check this link. many simple solutions for water and moisture removal

I have seen two types of these portable dehumidiers. One holds the condensate in a tray or tank, the other has a rubber hose that you stick down a nearby floor drain. If it is working properly, the tray or the drain hose will show lots of water.

As for heating, then yes a dehumidifier will heat the air in the area. All the power going into the unit is eventually converted to heat in the local area. These units are intended only to take moisture out of air, not cool it.

you better believe it. this old money pit is 90 years old. the water drains to a container inside the dehumidifier. I empty it every 1-2 days. It would be rather difficult due to the grade to hook up a hose to let the water drain out to the outside.

hoping the french drain that is gonna be put in will slow a little of the water problem..... or maybe get a hard wired, vented to the outside dehumidifier....

thx - Craig

The dehudified air is blown over a radiator coil similar to that found on the back of a refrigerator. That warms it by a degree or so with each pass of air through the machine. The effect is cumulative and after a while dust in the dried air becomes an irritant. A partial solution is to use a split air-conditioning unit which will both cool and dehumidify the air inside the garage.

It's worth noting that if the floor of your garage is porous it will continue to suck moisture out of the ground. You will need to install a vapour barrier of some kind.

(kim)

That is not always true. I bought an inexpensive window a/c this summer. It doesn't exhaust anything outside. It recirculates the inside air over the cold (condenser) coils and blows outside air over the hot (evaporation) coils. Never do the twain airflows meet. But yes, a/c does dehumidity the inside air. Any water from the inside air that condenses on the condenser coils drains outside.

The fundamental principle is that warm air can hold more water vapor than cold. Humidity is usually measured as "relative humidity" or RH. This is relative to how much water vapor the air can cold AT A PARTICULAR TEMPERATURE. RH by itself doesn't tell you the whole story. Air at 40 deg and 50% RH is holding a lot less water vapor than air at

I agree that an a/c probably does a better job of dehumidifying than a dehumidifier in many cases. The advantage of the dehumidifier is that it is cheaper, uses less energy and you don't have to punch a big hole on the wall to hang the evaporator coils outside. The disadvantage of the dehumidifier is that all the waste heat stays in the room you are trying to dry out. This raises the room temperature which just increases the ability of the air to hold more water vapor. Yes, the RH will go down, but since the air temperature may go up, the total amount of water vapor in the air may also go UP. An a/c also condenses water vapor on the condenser coils, but it LOWERS the room temperature as well, thus lowering the absolute capacity of the air to hold moisture.

Have you considered a vapor barrier?

Greg

It's actually the other way around. The evaporator coil is cold and the condenser is hot :o)

(kim)

and you're complaining about the humidity? I've been getting a gallon of water from the dehumidifier in my basement about 2 to 3 times a day!

A portable A/C is an ideal solution to your situation. You only need to provide about a 6" duct to the outside and you can have a cool and dry room.

Portable A/C exhaust the warm air to the outside. As far as moisture goes, some models need to be drained (like a dehumidifier). Other models spray the condensed moisture over the condenser thus evaportaing the water into the warm exhausted air.

And their price (and size) has come down dramatically within last few years.

Peteski

That's what I meant. There are 2 separate air circulations in a window unit. A/C is like a thermal pump. It "pumps" heat from the inside circulation to the outside. And the moisture from the evaporator (cool) coils is drained to the outside.

When you look at a dehumidifier in a simplified way, it would look like the window A/C unit if you were to remove the metal housing which separates inside and outside circulations (and place the entire unit inside of a room).

Those are evaporator coils, not condenser coils. But an average dehumidifier consumes as much energy as a small window A/C unit (5000-7000 btu). That is because the dehumidifier has the same major parts as a A/C unit.

A dehumidifier is roughly the same price as a small A/C window unit (again, because they are built in a similar way).

Some examples:

Let's say the temperature is T and humidity of the air is H grams per cm^3. When the saturation humidity is reached, then water droplets form. The body as a direct sensor of humidity is sensitive to the relative humidity RH, which is the ratio of H to the saturation humiidity. But this saturation varies with temperature: when the air is warm, more water vapor can be kept in gas form and therefore for a given amount of humidity H, the relative humidity RH actually drops.

Now, if it drops in the air, it means more water on the ground can use some of the available warmth to evaporate and go into the air, making the humidity higher again. And guess what, when T rises and then H and RH rise, your body notices :-) So, if you have a damp place and you are heating it at the same time as you are trying to dehumidify it, you are creating a nice little energy cycle powered by your humidifier, probably going to overstretch its capabilities at dehumidifying although its work as a heater will be less inhibited (since everything at first will be a heater before it goes and does anything else useful).

So my advice is to find a way to cool down the place more. You will reduce the strain on the dehumidifer as well as making yourself more comfortable.

Ah, just saw Greg's post! Nice explanation. Getting rid of the hot air is the way to kill 2 birds with one stone.