Controlling Window A/C Unit

[Extreme-Z]

Hey Guys,

This might be more of an electrical/appliance type question but thinking somebody here has probably done this so figured I'd ask

I have a 30x14 shed that I just got in May and I'm already having some mold/moisture problems inside the shed. It's a metal shed and I'm in Florida and have read this isn't uncommon. I installed an 8,000 BTU window air conditioning unit this week to reduce the humidity inside the shed and it seems is working OK. It is a newer unit and one thing I don't like about it is that if it loses power even during a glitch it turns off, and won't come back on until somebody hits the power button again (digital unit) and this is no good for a shed air conditioning that I may not even go into weekly. But, I do have another older 12,000 BTU window unit that has manual knobs! I'm thinking of installing that one instead and plugging it into a Z-Wave outlet that I can control with HomeSeer. My question is, do any of you see any harm in controlling an older window unit not using its own thermostat but cutting power and restoring power at the outlet. I don't think there would be any harm to it with an older unit like I have but figured I'd ask to see what you guys thought

Also, what would be another idea, is I have a gizmo that monitors temperature and humidity and has contacts that close on high/low temperature/humidity. I should be able to rig it up such that I control the Z-Wave outlet using humidity which is what I'm concerned about more than temperature. If any of you do this, do you have a good humidity number that you use to prevent mold/moisture build-up? I have a Kill-A-Watt hooked up now and based on a few days worth of monitoring, even set on a higher temperature, it is going to cost me around $20 a month so thinking if I control off humidity I might be able to reduce that cost a little.

Thanks much!

[TomTom]

You can turn your older Ac unit on off with a z-wave outlet- that should be no problem. In fact I installed a window AC unit for my work garage this past summer that does exactly this. Especially since I experience power outages too during storms. My plan is to put a zwave multisensor to monitor the temp in the garage and have hs kick on the Ac when it reaches a certain temp. Right now it is set up to come on and off only during certain time periods when I'm most likely to be in there.
There are also z wave multisensors that give temp and humidity( everspring ??).

Also when I see mold/moisture issues I've learned one needs to look for
1) sources of moisture near by( soaked ground, water intrusion, water splashing, lack of adequate sun light to dry up water after rains, etc).
2) ventilation- humid environment with a lack of adequate ventilation is a potential location for mold/moisture problems. Intake and outtake vents in a closed space, esp one that can warm up like a metal shed in sunlight) can prevent mold problems. I have high humidity too and in my sheds I've put soffit vents, thin 6x9 metal ones from homedepot $3, on the SIDES of my shed to allow for air flow. Its about 2 feet above the floor. Also the side vents help in the case of floods( water can flow in and out)- this is actually code in many counties near water.

This advice is just from my experience.


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[Extreme-Z]

Thanks much, Tom! I did have some leaks in the shed which were repaired last week under warranty right before I put the A/C in. The mold (kind of the dry type mold) wasn't in the areas of the leaks but could have been due to the all the moisture in the shed caused by the leaks. I didn't want to risk having my stuff get ruined so got the leaks fixed and put an A/C unit in at the same time. We'll see how it goes from here

Thanks!

[wkomorow]

I am using a remotec zxt-120 to control my AC. It has a temp sensor but not a humidity one. It is a bear to find the right code for the AC, the manual list dozens for each model, but once you do it works great.

http://smile.amazon.com/Remotec-Z-Wa.../dp/B00CJBBYS0

[Extreme-Z]

I am using a remotec zxt-120 to control my AC. It has a temp sensor but not a humidity one. It is a bear to find the right code for the AC, the manual list dozens for each model, but once you do it works great.

http://smile.amazon.com/Remotec-Z-Wa.../dp/B00CJBBYS0

That's cool! That might be an option if I stick with the newer style digital one. I don't have a remote for it but it does look like there is an IR window so I presume it probably came with a remote (got it used)

[LeoS]

I have had a couple of badly ventilated store rooms in the house too. Installing an exhaust fan (30w unit I think) in the room did wonders to lowering humidity by about 20-25%. The room is approx 20x20... it used to smell of mold and cardboard boxes just soak up the moisture in the air and turn to !@#!@ Now the room is fine.

I also have a small windows/split aircon installed in another smaller storage (15x10) that I tried to automate with plcbus (simlar to x10) relay. That didn't last long... after a few months I had to service the aircon (busted cpacitor or some such). Not sure whether cutting the power with the plcbus relay had anything to do with that or not. Now I use a plcbus IR transmitter to control the aircon.

[Extreme-Z]

I have had a couple of badly ventilated store rooms in the house too. Installing an exhaust fan (30w unit I think) in the room did wonders to lowering humidity by about 20-25%. The room is approx 20x20... it used to smell of mold and cardboard boxes just soak up the moisture in the air and turn to !@#!@ Now the room is fine.

I also have a small windows/split aircon installed in another smaller storage (15x10) that I tried to automate with plcbus (simlar to x10) relay. That didn't last long... after a few months I had to service the aircon (busted cpacitor or some such). Not sure whether cutting the power with the plcbus relay had anything to do with that or not. Now I use a plcbus IR transmitter to control the aircon.

That's my exact problem... besides a couple signs of mold starting I was noticing the cardboard boxes I had out there felt "soft" and "weak" and some bottom ones where I had stuff stacked on top started to collapse.

If I could get by with running just an exhaust fan that would be great and a lot cheaper! Does your exhaust fan run continuously and I presume the room is insulated? My shed isn't insulated at the moment but I may just try the exhaust fan too. I could put one in the gable end of the shed and there is a ridge vent in the shed so the air should change out with no problem so long as it doesn't "short circuit" too much and go just directly from the ridge vent out the fan. I would think an exhaust fan would just suck in the humid air and maybe make it worse but I suppose the movement of air is what helps? Either way, if it worked for you it is worth a shot and could save me a good amount of money each month in electric costs

[LeoS]

That's my exact problem... besides a couple signs of mold starting I was noticing the cardboard boxes I had out there felt "soft" and "weak" and some bottom ones where I had stuff stacked on top started to collapse.

If I could get by with running just an exhaust fan that would be great and a lot cheaper! Does your exhaust fan run continuously and I presume the room is insulated? My shed isn't insulated at the moment but I may just try the exhaust fan too. I could put one in the gable end of the shed and there is a ridge vent in the shed so the air should change out with no problem so long as it doesn't "short circuit" too much and go just directly from the ridge vent out the fan. I would think an exhaust fan would just suck in the humid air and maybe make it worse but I suppose the movement of air is what helps? Either way, if it worked for you it is worth a shot and could save me a good amount of money each month in electric costs

Yes, the room is nearly completely isolated. I put the exhaust at the back of the room, and installed some ventilation slits near the entrance (front) to create the cross vent...

I had temp\humidity sensor installed before the exhaust and had collected some numbers, so I setup the vents accordingly (I think they're on about 15 hours/ day. Not quite 24 hrs).

[Gunneyk]

Since it is a new AC unit it is likely to have a remote with it. If so then you can control the AC unit with something like this: http://www.homecontrols.com/Zipato-Z...r-ZPRMZXT120US
Just have an event that checks every so often for temp and or humidity and adjust the AC unit appropriately. If it went off then the next time around it would turn it back on.
Edited: I just saw the other links that were posted and it appears that the Zipato unit is a re-branded Remotec device so I have to assume they do exactly the same thing except the Zipato is $20 more.

[TomTom]

Controlling Window A/C Unit

I would encourage to look at passive or active ventilation before Air Conditioning the area. Window AC Unit running in the summer months can add up in the FL environment. If your looking at active ventilation options, you may want to check out some of the options they have for crawl spaces. These spaces are prone to higher humidity due to being right above the ground and poor drainage conditions which compound the matter. While the vents look small they are enough to ventilate big areas. The square footage rating is listed on the units. I could be wrong but something like a 50cfm is enough for 2000sqft crawl space( just to give you an idea). Fans come with or without humidity controls. These fans consume very little power( essentially PC type fans). The brand I'd recommend is
http://www.amazon.com/Tjernlund-Unde.../dp/B000N503CM

I've also seen where one took a Pc fan and hardwired it to a crawl space humidity control.

Regarding insulation for your metal shed. Part of the problem in high humidity areas is the condensation that develops in side a closed space during early morning/late evening hours. This condensation without adequate ventilation is a potential moisture issue. I built 12x10 shed a few years ago and after a lot of reading I went with roofing tar paper to keep moisture out. This was used before the days of tyvek and many old timers only use roofing tar paper for this purpose. The other more costly route is fiberglass insulation rolls. The shed, passive ventilation and tar paper, has had no moisture issue in the last 8 years.


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[Extreme-Z]

Excellent info. Thanks much, guys, for letting me in on your experiences.

If I can get by without the air conditioning, and it sounds like I can, that will be the way to go to save me some decent money!

Tom, did you just put the tar paper on the inside of the shed walls? Did you put it tight to the metal walls or did you staple it to the 2x4s leaving an air gap between it and the metal walls and roof?

Thanks!

[TomTom]

Tom, did you just put the tar paper on the inside of the shed walls? Did you put it tight to the metal walls or did you staple it to the 2x4s leaving an air gap between it and the metal walls and roof?

Thanks!

My shed is wood. So when I was building it, after I framed it up, I stapled the tar paper all around the shed(outside), then I put up the plywood on top of it. I see the problem with a shed that is already build, but could still use tar paper, you would just need to use a good exterior grade caulk that is also adhesive( like loctite polyseam -at home depot) to glue it to the metal. Put the caulk in just enough areas to hold it up, but dont "paint" on the caulk. See attached picture. No caulk on the bottom, because you want a way if there is "excess" moisture or if there is water intrusion -for it to have a way out. Make sure you roll the roll of tar paper from top to bottom within the stud.


Tar paper is your vapor barrier . Tar paper offer moisture control, but lacks in real insulation quality. YOU DONT NEED TO DO THE Below and could do it in time. I haven't need it in a very humid environment. I've done this for a family member though.

In time, could buy those large pieces of white foam sheets sold at home depot and cut that to fit into the metal studs that run up to the roof. You could use the same caulk to glue the sides of the foam to the sides of the metal studs.
I'm not a contractor or anything, but construction has been a hobby of mine for the last 8 years. So I only say from what I've actually done, which is always after a lot of reading and research.

[Extreme-Z]

Thanks for the info! My family is in construction and I've done a bunch of stuff over the years so I get the picture of what you are saying. I've got an air stapler so I could probably just lay a slightly larger piece inside the studs and staple to the studs very close to the metal sides. That would likely be cheaper than caulk!

Thanks!

[TomTom]

Ok cool, if your stapling directly on to the tar paper, it may go through the paper or may not hold up over time( things rubbing up against it). You may want to get a piece of lattice strip 1/4" x 1" x 8' (like $1) and cut that into pieces( 1.5") so that you can put that on top of the tar paper and staple on to the wood. Just a thought.

Thanks for the info! My family is in construction and I've done a bunch of stuff over the years so I get the picture of what you are saying. I've got an air stapler so I could probably just lay a slightly larger piece inside the studs and staple to the studs very close to the metal sides. That would likely be cheaper than caulk!

Thanks!

[Extreme-Z]

Ok cool, if your stapling directly on to the tar paper, it may go through the paper or may not hold up over time( things rubbing up against it). You may want to get a piece of lattice strip 1/4" x 1" x 8' (like $1) and cut that into pieces( 1.5") so that you can put that on top of the tar paper and staple on to the wood. Just a thought.

Yes, for sure. When I used to do roofing with my father we used half dollar or so sized metal discs. Those got hot in the summer. LOL

Thanks again!