# dehumidifier in basements



## cibula11 (Jan 6, 2007)

Amitabh said:


> Hi All
> 
> If one's basement is completed and has a closed furnace room Does a portable dehumidifier still collect the moisture, if its placed in the furnace room, from other areas.
> 
> or does each room needs its own dehumidifier.


If the furnace is running, most likely that particular room will be drier, especially since it's a furnace room. Typically, you'd want a dehumidifier in areas that have higher humidity levels for both comfort and moisture.

One per level is probably okay for a finished space. My humidifier runs non stop during wet months. You can certainly use two if the one is always running and humidity levels are not lowering to your liking.


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## Amitabh (Oct 21, 2010)

hmmm - i really dont want a dehumidifier in my man - cave...


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## cibula11 (Jan 6, 2007)

Amitabh said:


> hmmm - i really dont want a dehumidifier in my man - cave...


They aren't that big and most of them sound like a quiet fan. You can tuck them under side tables, tables, desks, etc. 

Do you know what the humidity levels are? I guess the scary alternative is to have your man cave become a mold cave. 

Is your basement musty and humid? Just curious as to why you asked about dehumidifiers in the first place.


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## Amitabh (Oct 21, 2010)

right now - and it just rained yesterday, 37%, normal 34%, but not finished, am trying to finish.

xps insulation right now. i removed the FG blanket and plastic crap


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## elbowgreece (Apr 10, 2014)

It's worth it to find some space in the mancave for it. Basements will always have a higher risk of mold damage and a dehumidifier can go a long way to prevent that.


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## gregzoll (Dec 25, 2006)

Amitabh said:


> Hi All
> 
> If one's basement is completed and has a closed furnace room Does a portable dehumidifier still collect the moisture, if its placed in the furnace room, from other areas.
> 
> or does each room needs its own dehumidifier.


It really depends on how humid it gets down there. As long as you have vents and returns down there. It should stay within what the upstairs is.

Right now my basement is at 56% rh, 65 deg. F. Upstairs is 43% rh, 73 deg. F. I try to keep our basement cool and no higher then 56% rh, 69 deg. F during the Summer.

Never had any issues with mold or mildew down there.


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## Bob Sanders (Nov 10, 2013)

gregzoll said:


> It really depends on how humid it gets down there. As long as you have vents and returns down there. It should stay within what the upstairs is.


That all depends on how old your basement is! I live in a 100 year old house and the concrete is not what it once was. As a result the humidity is always pretty high and I have to run a dehumidifier for most of the summer. If I don't then the sweat off the toilet tank and copper lines causes issues.

That being said, my dehumidifier is in the other room (furnace room) and I have connected ductwork to the machine and punched it through the drywall. Finished the return and intake ducts with normal vent covers. This works but but there was a slight 'dampening' effect with the built in humidistat so I maxed it out and rigged up a wall mount humidistat in the main room with a plug on it, which now supplies power to the dehumidifier.

You can still hear it running when it's on, but it's not nearly as loud.


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## gregzoll (Dec 25, 2006)

Mine is coming in pretty close. It is around 78 years old. It stays dry down there all of the time. I just had to turn the fan on today, due to it was getting a little musty smelling downstairs.


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## cj133 (May 16, 2011)

I live in a 150 yr old house and my 50pt dehumidifier starts in April and never shuts off until October. It keeps the humidity down to around 40-45% most of the time which is nice, but the dehumidifier probably hates me.

Stone walls, partial concrete floor, lots of dirt floor.

In my opinion, if the furnace room gets air circulation from the rest of the basement it will probably work fine in there. Give it a shot and use a hydrometer to see how your man cave stays. If it stays comfortable, say around 40-50% then call it good.


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## stadry (Jun 20, 2009)

' dont want a dehumidifier in my man - cave ' - easier solution is move your ' man - cave ' to a dryer location

no one alive can get 5gal of wtr into a 4 gal bucket :no: its only april & ours has been running a wk steady,,, probably that's why the machine's called ' AUTOMATIC ' :thumbsup: its in the walkout bsmt level where we have 1 vented bathroom, the exercise room, utility room, my office, & genl other space,,, you do have choices - but you don't like them,,, so move the room to somewhere else !

how difficult is that ? just suck it up :laughing:


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## beenthere (Oct 11, 2008)

cj133 said:


> I live in a 150 yr old house and my 50pt dehumidifier starts in April and never shuts off until October. It keeps the humidity down to around 40-45% most of the time which is nice, but the dehumidifier probably hates me.
> 
> Stone walls, partial concrete floor, lots of dirt floor.
> 
> In my opinion, if the furnace room gets air circulation from the rest of the basement it will probably work fine in there. Give it a shot and use a hydrometer to see how your man cave stays. If it stays comfortable, say around 40-50% then call it good.



If the furnace room gets its combustion air from outside, then making a hole in the wall between it and the man cave. Will increase the humidity of the man cave. Even with the dehumidifier running.


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## cj133 (May 16, 2011)

beenthere said:


> If the furnace room gets its combustion air from outside, then making a hole in the wall between it and the man cave. Will increase the humidity of the man cave. Even with the dehumidifier running.




Very true and a good point that I didn't think of.
However there is a good chance the furnace room pulls combustion air from it's surroundings or the furnace could even be a direct vent in wish case it doesn't need combustion air fed into the room.

I suppose at this point we need to know if the furnace needs combustion air and if so where does it come from?


Amitabh : Does your furnace have a chimney or does it vent via PVC piping? Also are there any vents from outside to the furnace room, like grates, automatic dampers, anything? Can you show us some pictures?


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## gregzoll (Dec 25, 2006)

We ran the a/c all day yesterday. Downstairs for me stayed around 56% rh, 66f. Upstairs was at 70f 44%rh, even though the thermostat was at 72f. Did not take long to pull it down from 78 to 70.


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## Amitabh (Oct 21, 2010)

cj133 said:


> Amitabh : Does your furnace have a chimney or does it vent via PVC piping? Also are there any vents from outside to the furnace room, like grates, automatic dampers, anything? Can you show us some pictures?


the furnace vents outside via a PVC pipe. The humidity right now is 40%rh. But the basement is yet to be finished. I am thinking about the future, placement of grates (for intake and outtake) and finally level of humidity.

What i did notice in my basement (and going off topic), is that i only have one return opening in the entire unfinished basement and thats not even in the middle of the room, its off to one side.

I wonder if i installed at least 1 more intake - i think that should improve air movement and perhaps reduce humidity?

I will definitely install grates in the furnace room, just so air moves in that room


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## gregzoll (Dec 25, 2006)

If at 40%, that is good, but a little too low. Should be really around 50-52%. Too dry you start getting Static Electricity.


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## beenthere (Oct 11, 2008)

Amitabh said:


> the furnace vents outside via a PVC pipe. The humidity right now is 40%rh. But the basement is yet to be finished. I am thinking about the future, placement of grates (for intake and outtake) and finally level of humidity.
> 
> What i did notice in my basement (and going off topic), is that i only have one return opening in the entire unfinished basement and thats not even in the middle of the room, its off to one side.
> 
> ...


Does it also get its combustion air from outside via a PVC pipe? Do you have a gas fired water heater in the same room, if so where does it get its combustion air from.

installing another return could put the room into a negative pressure and increase humidity if it has to pull in outside air.


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## Amitabh (Oct 21, 2010)

beenthere said:


> Does it also get its combustion air from outside via a PVC pipe? Do you have a gas fired water heater in the same room, if so where does it get its combustion air from.
> 
> installing another return could put the room into a negative pressure and increase humidity if it has to pull in outside air.


hey - started a thread in HVAC now - dont want to hijack my own thread 

but to answer your question

combustion air is from outside for both Furnace and Water tank.


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## beenthere (Oct 11, 2008)

If they draw air in from the outside. then putting a dehumidifier in the furnace room and installing connecting vent to the other room/rooms, it will defeat the purpose of the dehumidifier.


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## Bob Sanders (Nov 10, 2013)

beenthere said:


> If they draw air in from the outside. then putting a dehumidifier in the furnace room and installing connecting vent to the other room/rooms, it will defeat the purpose of the dehumidifier.


My dehumidifier is in the furnace room, but its intake vent has been extended to the main room. So, the Dehumidifier is taking air from the main room, and delivering back to the main room (minus the water of course).
The machine is in the furnace room merely to cut down on the noise, which you can still hear... just not nearly as loud. It's also easier for me to run the drain hose there since the main stack is right beside the furnace.


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## cj133 (May 16, 2011)

Bob Sanders said:


> My dehumidifier is in the furnace room, but its intake vent has been extended to the main room. So, the Dehumidifier is taking air from the main room, and delivering back to the main room (minus the water of course).
> The machine is in the furnace room merely to cut down on the noise, which you can still hear... just not nearly as loud. It's also easier for me to run the drain hose there since the main stack is right beside the furnace.


Bob,

What did you do for a trap? I had looked for a solution for this years ago and all I could find was doing a basic standpipe for a cloths washer which seemed a bit much. I ended up using a little giant condensate pump that pumps it into my backyard.


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## beenthere (Oct 11, 2008)

Bob Sanders said:


> My dehumidifier is in the furnace room, but its intake vent has been extended to the main room. So, the Dehumidifier is taking air from the main room, and delivering back to the main room (minus the water of course).
> The machine is in the furnace room merely to cut down on the noise, which you can still hear... just not nearly as loud. It's also easier for me to run the drain hose there since the main stack is right beside the furnace.


As long as the connecting vent is not communicating to the furnace room also, that works.


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## creeper (Mar 11, 2011)

a tidbit...keeping the furnace fan running in the off season helps keep the basement air circulating plus it sucks all the cool basement air into the upper living space. You will need to turn on the a/c less often.


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## Bob Sanders (Nov 10, 2013)

cj133 said:


> Bob,
> 
> What did you do for a trap? I had looked for a solution for this years ago and all I could find was doing a basic standpipe for a cloths washer which seemed a bit much. I ended up using a little giant condensate pump that pumps it into my backyard.


My dehumidifier has been placed on a shelf about 4 feet up so that it can drain into the stack with straight gravity. A simple U bend was placed in the hose which forms a sort of P trap. It works fine.


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## Bob Sanders (Nov 10, 2013)

creeper said:


> a tidbit...keeping the furnace fan running in the off season helps keep the basement air circulating plus it sucks all the cool basement air into the upper living space. You will need to turn on the a/c less often.


You should keep it running pretty much all the time anyway. There is a concern in basements over Radon gas, particularly in our part of the world.

Still, even with the blower on there is that cool, basement feel to the air as you go down. Dehumidifiers kill that issue completely. It feels like a true extension to the house. The air is warm and dry and welcoming.


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## cibula11 (Jan 6, 2007)

Bob Sanders said:


> You should keep it running pretty much all the time anyway. There is a concern in basements over Radon gas, particularly in our part of the world.
> 
> Still, even with the blower on there is that cool, basement feel to the air as you go down. Dehumidifiers kill that issue completely. It feels like a true extension to the house. The air is warm and dry and welcoming.


I've heard from HVAC guys that running your furnace fan year round will kill your furnace in no time at all. I'd contact a professional HVAC person to confirm whether or not running the fan is a good option.


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## beenthere (Oct 11, 2008)

cibula11 said:


> I've heard from HVAC guys that running your furnace fan year round will kill your furnace in no time at all. I'd contact a professional HVAC person to confirm whether or not running the fan is a good option.


Won't kill the furnace.

It does however tend to raise the humidity in the house in the summer as it will re-evaporate some of the water of of the cooling coil(evaporator).

If a basement has a radon problem, but no radon removal system. Then the duct system should be sealed from the basement.


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## Bob Sanders (Nov 10, 2013)

cibula11 said:


> I've heard from HVAC guys that running your furnace fan year round will kill your furnace in no time at all. I'd contact a professional HVAC person to confirm whether or not running the fan is a good option.


I have to replace my blower motor about every three years. Last one I stuck in cost something like $68 plus tax.


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