reply to iknow
Re: 50 or 70 pint dehumidifier
said by iknow:i have found this to be true the dehumidifier will output heat. But there is a mystery i can't solve . Years ago in the house i grew up in there was an old sears coldspot or kennmore . There was no AC anywhere in the house. When the humidity hit the dehumidifier was run. During a heatwave since there was no AC in the house the finished basement was the retreat. With the dehumidifier running that basement never got hot and either did i feel any hot air coming out of it. This took in air through the front panel where there were louvers. The air blew out the back. At the bottom in the rear was the condensate pan you emptied (there was a hose provision but the drain pan was used) It collected condensate fine. For the life of me i can't figure out WHAT was different about that made in USA dehumidifier VS the dehumidifier on the market imported from china today. In theory a dehumidifier is a dehumidifier and should work the same now as it did then. said by Lurch77:
Most dehumidifiers pass the air first over the evaporator, then over the condenser. They shouldn't change the temperature of the space significantly. Plus many spaces, like a basement, are not well suited for installation of a window unit. And the space gets very cold as it runs so much to remove the humidity.
you'd think they would not change the temperature significantly by design, but every one i've used makes it hot as hell in the room it's in. also, in the summer, it gets too hot in my basement for comfort, so an AC cools and removes the humidity there, makes it quite dry actually, without being too cold. this does depend on a particular situation, but it seems a waste to use a dehumidifier, then the AC has to remove that heat.
I assume that was due to size and efficiency. The electrical energy consumed by the dehumidifier will heat the space. How much depends on: how much energy is consumed by the dehumidifier, how large the room is, and are they sinks/sources of heat. In a basement ground temperature is usually lower then air so added heat will flow through the walls into the surrounding soil.
We have a unit in our basement and while the heat is noticeable while it is running on balance the lower humidity improves comfort. Unfortunately our basement is fairly well connected to the 1st floor so humidity levels are greatly influenced by weather conditions.
reply to norbert26
My guess is that newer units remove considerably more humidity than those made a couple of generations ago. The process of converting water vapor to a liquid state releases heat. This heat energy as well as the heat generated due to inefficiencies in the unit itself are released into the room.
Water vapor will only condense onto another surface when that surface is cooler than the dew point temperature, or when the water vapor equilibrium in air has been exceeded. When water vapor condenses onto a surface, a net warming occurs on that surface. The water molecule brings heat energy with it.
The enthalpy of condensation (or heat of condensation) is by definition equal to the enthalpy of vaporization with the opposite sign: enthalpy changes of vaporization are always positive (heat is absorbed by the substance), whereas enthalpy changes of condensation are always negative (heat is released by the substance).
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reply to Zach 58
Well mystery solved. That dehumidifier from years ago must have been low power. The house only had 60 AMP service and the condensate pan was not that large. Fast forward to the present. A year and a half ago i bought a dehumidifier to boost / assist an AC in an adjoining room . The room i placed the dehumidifier in has those sliding windows that are a PITA to mount a window shaker in. I put the AC window shaker in the adjoining room and it cools both rooms. Sometimes if humidity is extreme (like during the night) the AC will cool but it may get humid in the other room. I set the dehumidifier at 60% so it wont run too long and not get too hot. I made the mistake of the dehumidifier being over sized at 70 pints . Now i know i needed it smaller but whats done is done now i will live with it. All this said they have combo AC / dehumidifiers on the market. These have a big heat exhaust hose you can run to a window and exhaust the heat to the outside. If its damp / cool you can run it as a standard dehumidifier. This would address the issue of heat build up. The ones i have seen do about 12,000 BTUs but this will work where you can't install a window shaker.