Dehumidifier Question

[teddy bear]

So I kept the Frigidaire. I wasn't clear on one thing, though. Since the internal humidistat is so inaccurate and causes short, constant cycling of the compressor, do you think I should set the humidifier to constant on and use a normal timer or an external plug in humidistat (DAYTON 1UHG2 Dehumidifier Control,Plug In 120 V)? Which one?

If I were to use a timer, does it need to be a heavy duty one, or will a standard timer (type people use with lamps) be safe? What specs should I look for?

Thanks again!

The Dayton control is OK and offers control based on %RH. The timer will overrun the dehu during low %RH and may not operate enough during high %RH.
Keep us posted.
Regards TB

[Ziocarl]

Will do, and thanks again.

Oh! Just remembered something that has been plaguing me for years and is right up your alley. My house is sort of built into a hill, so the garage is actual attached to the basement and a part of the bottom level of the house. You have to walk up a set of outside steps to get into the main level of the house. The garage is cinder block and partially underground (side and back). Ceiling of garage is dry-walled and insulated, I believe, but main AC trunk runs through that ceiling and leads to 4 vents in my family room above....this might contribute to a little cooling in the garage (probably not much though). It gets VERY humid in the garage. So much so that by the end of the summer, most cardboard or fabric items have some mold on them. I've been trying to think about how to fix this. If I open the garage during the day, I let in a ton of hot water-logged air, which cools over night and results in even higher RH. Have thought about the following:

1) seal concrete floor and walls to prevent moisture penetration from ground
2) run a dehumidifier in garage (seems unrealistic and expensive)
3) install some sort of vent in the side, cinder block wall of the garage (facing outside) with a fan controlled by a plug in humidistat.

With #3 though, won't I just be pulling in more 70% + RH air from outside? Is that better than what's in the garage to begin with? How can I get the garage down to below 60% RH?

Thanks.

[energy_rater_La]

oh btw...my house is built into the side of a hill!!
LOL!

[teddy bear]

Will do, and thanks again.

Oh! Just remembered something that has been plaguing me for years and is right up your alley. My house is sort of built into a hill, so the garage is actual attached to the basement and a part of the bottom level of the house. You have to walk up a set of outside steps to get into the main level of the house. The garage is cinder block and partially underground (side and back). Ceiling of garage is dry-walled and insulated, I believe, but main AC trunk runs through that ceiling and leads to 4 vents in my family room above....this might contribute to a little cooling in the garage (probably not much though). It gets VERY humid in the garage. So much so that by the end of the summer, most cardboard or fabric items have some mold on them. I've been trying to think about how to fix this. If I open the garage during the day, I let in a ton of hot water-logged air, which cools over night and results in even higher RH. Have thought about the following:

1) seal concrete floor and walls to prevent moisture penetration from ground
2) run a dehumidifier in garage (seems unrealistic and expensive)
3) install some sort of vent in the side, cinder block wall of the garage (facing outside) with a fan controlled by a plug in humidistat.

With #3 though, won't I just be pulling in more 70% + RH air from outside? Is that better than what's in the garage to begin with? How can I get the garage down to below 60% RH?

Thanks.

Controlling mold requires several hours of <50%RH daily. Of course, a timer controlled dehumidifier would be a fix. The more air tight/moisture proof the space is, the smaller the dehu could be. A small dehu operating for several hours each evening could be a solution.
Another fix could be several hours of enough dry air from the home to the space during times of the year when the garage was damp.
A small duct fan on a timer sounds simple. This assumes that you have a little extra drying ability in your home to deal with the outside air that will pass through the home to the garage. If you had (or after you have) a whole house dehu you could route a 4" supply of dry air to the space. 30-50 cfm of dry air for 6-8 hour per evening would be enough.
I would wary about this problem any more this year, next spring remove anything that can get moldy or??
By the way, overheating from a dehumidifier indicates a too low of a setting.
Regards TB

[Ziocarl]

I had always figured that running a dehumidifier in the garage would make me NEVER want to open the big double wide garage door because it would mean dehumidifying the outdoors, but it sounds like from what you are saying I could just set the dehumidifier to run at night, while the door is closed. Sealing the floor and walls would reduce run-time further...got it.

Regarding the vent, I was thinking that it would be on the OUTSIDE wall venting out to the outside, along with an intake also on an outside wall...the idea was to bring outside air in, but then there is the issue of outside air during the summer being way over 50%RH. I see what you are saying about bringing in dry living space air, but how would that air be replaced in the home? I don't like the idea of pulling air into the living space through cracks and crevices, so would I have to create an outside air intake (crack a window)? Guess that would solve the "removing pollutants from the living space" issue, but otherwise, isn't that a less efficient route to the same results that you would get from simply putting a dehumidifier in the garage?

"By the way, overheating from a dehumidifier indicates a too low of a setting." - please explain.

Thanks.

[teddy bear]

I see what you are saying about bringing in dry living space air, but how would that air be replaced in the home? I don't like the idea of pulling air into the living space through cracks and crevices, so would I have to create an outside air intake (crack a window)? Guess that would solve the "removing pollutants from the living space" issue, but otherwise, isn't that a less efficient route to the same results that you would get from simply putting a dehumidifier in the garage?

"By the way, overheating from a dehumidifier indicates a too low of a setting." - please explain.

Thanks.

A small amount of outside infiltrates your home. An equal amount exfiltrates. The amount depends on the wind, stack effect, and exhaust fans. The most of the air moves through the cracks. 40 cfm into the garage means little. If you had a whole house dehu, you would bring in a small amount of air to assure correct air change during the mild calm seasons. The dehu could also provide dry air to the garage. The WH dehu has a timer to provide this during evening hours. When your clothes drier, bath fans, kitchen hood operate, the make-up air infiltrates through the cracks.

Regarding dehu settings. As the dehu warms the air, the %RH declines, -2%RH per degree rise. As you lower the setting of the dehu, the amount moisture removed decreases/KW used increases and the temperture rise increases. Make the %RH setting as high as acceptable. This will minimized the heat gain, as opposed to setting is lower which may require the dehu to run none stop.
Regards TB

[Ziocarl]

This might be crazy, but I always crack a window (even in winter) when I run any type of exhaust fan. I don't like the idea of air filtering through dirty crevices making it's way into my house. I also feel like it allows the exhaust fans, especially the bathroom ones that are a little undersized, move more air out of the house.

How would I bring air into the garage? a hole in the wall between garage and living space with a louvered fan on a timer? How do I ensure that the exhaust from the garage makes it outside instead of circulating back into the living space?

Thanks for the explanation on the dehu settings.

[teddy bear]

This might be crazy, but I always crack a window (even in winter) when I run any type of exhaust fan. I don't like the idea of air filtering through dirty crevices making it's way into my house. I also feel like it allows the exhaust fans, especially the bathroom ones that are a little undersized, move more air out of the house.

How would I bring air into the garage? a hole in the wall between garage and living space with a louvered fan on a timer? How do I ensure that the exhaust from the garage makes it outside instead of circulating back into the living space?

Thanks for the explanation on the dehu settings.

Maybe not crazy but a little different. Blowing 40 cfm into the garage and where the air goes does not make any difference. Some probably outside and the rest back to the home. The garage needs to be dry 3-4 hours a day to stop mold. A duct fan on a timer is ok.
Regards TB