I was given a newer 8000 btu window AC unit. I thought I'd put it in my 700 sq ft garage to use in addition to my dehumidifier that I run during the Summer months. I know that high humidity makes you feel hot, I was thinking the smaller AC unit used in conjunction with the dehum will provide decent relief. The garage is shaded for a good portion of the day. The first day I installed the AC the garage was 84 degrees on a 90+ degree day. Within 1.5 hours the temp was down to 78. Now I am trying to figure out the right balance between the units, run both the dehumidifier and AC on higher settings or both units on lower settings, causing either or to work harder and compensate for the other. I know the correct answer is to get a properly sized mini split, but I was given both of these units and if I can manage to get by with them it would take many years to make up the difference in $'s saved if I spent the money now to add a mini split. Any thoughts on this?
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Smaller ac and dehumidifier to cool garage
- Thread starter mikec35
- Start date
Jeepster04
Well-known member
- Joined
- Jun 25, 2013
- Messages
- 3,113
I would set the dehumidifier to whatever % I want and the A/C to whatever temp I want and let'er ride. It'll work out.
glentre
Well-known member
I think if you get a meter to read relative humidity, you will find running the ac unit will both cool and dehumidify to a comfortable level and that you will likely determine the dehumidifier will not be needed. They are expensive to run.
Glen
Glen
I think if you get a meter to read relative humidity, you will find running the ac unit will both cool and dehumidify to a comfortable level and that you will likely determine the dehumidifier will not be needed. They are expensive to run.
Glen
I agree. a small AC in a hot garage should have plenty of time to pull the humidity out. the dehumidifier is likely just adding cost without adding value.
TuxThePenguin
Well-known member
Yeah, running a dehumidifier and running an AC generally cost similarly. An AC will remove a certain amount of humidity and a certain amount of heat. Depending on the actual levels of heat and humidity in your area, as well as how leaky/ventilated your garage is, you may or may not find an AC to handle both aspects on its own. I also think it's worth trying just the AC if you haven't already.
But if you do wind up needing both, you're going to have to adjust them based on your specific conditions as well as your personal preferences. I don't think we can give much advice with that.
But if you do wind up needing both, you're going to have to adjust them based on your specific conditions as well as your personal preferences. I don't think we can give much advice with that.
Superbec
Well-known member
the dehumidifier creates heat that the ac has to move out, give the dehumidifier forward and just use the AC it also dehumidifies .
I use my dehumidifier in the early spring and fall when it's humid and no AC is needed -- once the AC starts that takes over. Those early times often need a bit of heat anyway -- no need to run together unless AC is so oversized that it does not run enough to remove humidity
the dehumidifier creates heat that the ac has to move out, give the dehumidifier forward and just use the AC it also dehumidifies .
Actually dehumidifier creates heat ( condenser) and cool ( evaporator) in the same box ........so it pretty much a wash. In a reasonably sized room you will see little warming or cooling.
nadogail
Well-known member
Thanks for sharing.
Actually dehumidifier creates heat ( condenser) and cool ( evaporator) in the same box ........so it pretty much a wash. In a reasonably sized room you will see little warming or cooling.
Except that it also creates more heat (motor running) than it creates "cool".
The wattage consumption of the dehumidifier can be directly correlated to the extra heat it makes.
Looking more closely at the window unit I see it has a dry button, basically runs the unit on low to prolong run time getting to temp. I'll try the unit by itself and see how it does. Since it's undersized I might be able to use the dry function, it may never get cool!
Actually dehumidifier creates heat ( condenser) and cool ( evaporator) in the same box ........so it pretty much a wash. In a reasonably sized room you will see little warming or cooling.
the latent heat of vaporization is released to the room as heat, (energy input to evaporate the water is now released as heat into the room). the wetter it is the more heat is released.
In addition to the plug wattage draw - no different than a space heater of the same wattage.
that's why air coming out of a dehumidifier in a humid room is much hotter than the exhaust air in a dry room.
Superbec
Well-known member
Actually dehumidifier creates heat ( condenser) and cool ( evaporator) in the same box ........so it pretty much a wash. In a reasonably sized room you will see little warming or cooling.
no, it's not a wash, you have a ~300w power input into the room, if you had the evaporator out of the room than it would cool the room very slowly .
the latent heat of vaporization is released to the room as heat, (energy input to evaporate the water is now released as heat into the room). the wetter it is the more heat is released.
In addition to the plug wattage draw - no different than a space heater of the same wattage.
that's why air coming out of a dehumidifier in a humid room is much hotter than the exhaust air in a dry room.
no, it's not a wash, you have a ~300w power input into the room, if you had the evaporator out of the room than it would cool the room very slowly .
If you put a dehumidifier in small closet .......you would see a slight increase in the temperature.
In real life .....in reasonable sized room the temperature gain is insignificant. As in almost not measurable.
Question: If you put freezer or refrigerator in a large closed room ran it days with the appliance door wide open...........Would the room be colder or warmer ? Yes, there might be puddle of water on the floor.
400 watt appliance might have 66% all in efficiency Fan/compressor in making the box cold but the door is open so it’s just “moving the heat around“.......33% left over as heat 125 watt in 1000-2000 sqft room would make little difference. 125 watt light bulb in closet might actually warm the closet.
Experts report on the topic:
“Dehumidifiers help to cool a room because we naturally feel a more humid room to be hotter, even if the temperature is the same as a lower humidity room. If you feel the air coming out of the dehumidifier, it is warm, but it will not increase the temperature inside the room.“
“The temperature increase in the supply or discharge air, compared to the incoming air stream, will vary between 15° – 25° depending on the load the dehumidifier has to take on. However, this does not mean that your home will increase in temperature by 15° – 25°.“
“This includes utilizing a dehumidifier, which will not change the room temperature but will remove humidity“
Last edited:
If you put a dehumidifier in small closet .......you would see a slight increase in the temperature.
In real life .....in reasonable sized room the temperature gain is insignificant. As in almost not measurable.
Question: If you put freezer or refrigerator in a large closed room ran it days with the appliance door wide open...........Would the room be colder or warmer ? Yes, there might be puddle of water on the floor.
400 watt appliance might have 66% all in efficiency Fan/compressor in making the box cold but the door is open so it’s just “moving the heat around“.......33% left over as heat 125 watt in 1000-2000 sqft room would make little difference. 125 watt light bulb in closet might actually warm the closet.
Experts report on the topic:
“Dehumidifiers help to cool a room because we naturally feel a more humid room to be hotter, even if the temperature is the same as a lower humidity room. If you feel the air coming out of the dehumidifier, it is warm, but it will not increase the temperature inside the room.“
“The temperature increase in the supply or discharge air, compared to the incoming air stream, will vary between 15° – 25° depending on the load the dehumidifier has to take on. However, this does not mean that your home will increase in temperature by 15° – 25°.“
“This includes utilizing a dehumidifier, which will not change the room temperature but will remove humidity“
Sorry, you're wrong. energy consumed by an appliance that exists only in that room is 100% dissipated into that room as though it were a resistive heater. this is fact.
if there's somewhere for that energy to go (like the concrete block walls and dirt surrounding your basement), it may not make a significant difference in measured temperature. that doesn't change the laws of thermodynamics.
a 400W appliance in a box (one could call a house a box) is a 400W heater, whether it does useful work or not.
yes, a dehumidifier produces air somewhere in the ballpark of 25F warmer than the air going in. kinda like a space heater on low. no, a space heater on low won't raise the temperature of my house by 25F.
my furnace putting out 140F air doesn't raise the temperature of my house by 140F either.
a dehumidifier in a room can, under the right circumstances both make the room "feel" cooler while in fact being warmer. this isn't qualitative, it's psychrometrics. it's objective/quantitative.
slackdaddy1
Well-known member
I have a WELL insulated 22x32 shop, I have a stndard room dehumidifier with a direct drain through the wall.
My shop is always about 10 deg cooler than the outside air on summer days.
But I was still getting rust on tools and project cars.
I installed a regular room dehumidifier, made a small shelf and direct drain to the outside.
No more rust, on a 95 deg day the shop is ok to work in.
I dont want or need an AC unit running all the time, besides, once it hits it's set degree mark, it wont be removing moisture.
The other thing with just A/C is that you are lower the temp of all your tools and equipment,, below the dew point of the outside air.
I would have the dehumidifier set to 50% humidity and on,, flip the A/C only when you are working in there.
My shop is always about 10 deg cooler than the outside air on summer days.
But I was still getting rust on tools and project cars.
I installed a regular room dehumidifier, made a small shelf and direct drain to the outside.
No more rust, on a 95 deg day the shop is ok to work in.
I dont want or need an AC unit running all the time, besides, once it hits it's set degree mark, it wont be removing moisture.
The other thing with just A/C is that you are lower the temp of all your tools and equipment,, below the dew point of the outside air.
I would have the dehumidifier set to 50% humidity and on,, flip the A/C only when you are working in there.