beverly hillbilly storm windows and cybernetic heat control

[JR.]

A while back I sealed up my house tighter than a scottish mouse butt hole, I didn't connect the dots between that and a chronic black mold problem (I live in MS) but recently the light bulb went off that less indoor humidity would be a good thing. Mold and such need humidity to flourish, so less moisture means less mold.

A couple days ago I invested in a new dehumidifier. The mid-sized one I wanted wasn't in stock at my local wally world so I bought a big dog 70 pint (per day) model... That's something like 8+ gallons a day... I am not getting that many gallons, but in two days I've pulled several gallons of water from my house, mainly from my back bedroom...

it is fun watching the fancy display on this puppy (room temp and RH) As we all know (?) relative humidity is factored by the air temp. Warmer air holds more moisture so for a given volume of air, with the same amount of moisture, the warmer the air the lower the RH. Another tidbit about a 70 pint dehumidifiers is they throw out a bunch of heat. The dehumidifier is basically a cooled refrigerator coil to condense moisture from the air passing over it, but the waste heat from the process dumps into the room, so net-net it's a room heater.

In a closed space as the dehumidifier extracts moisture while heating the air, as the room heats up, the RH drops to the lower adjustment limit (30%). So I have to both run the air at full blast to keep the room temp down while extracting water. It would probably be more efficient if I could force it to work down below 30%..

As I let the air conditioner cool down the room I see the RH climb... but my inner science geek knows that the actual moisture level is stable to still dropping. Also I have to keep emptying the water tank Another gallon plus of water out of my bed room this afternoon...

My judgement now is that this will take several days to pull the decades of extra moisture out of my living space. My frugal practice of only running the air as little as needed just makes matters worse.

Right now my back bedroom has the air conditioner cranked at full and temp is slowly dropping. It's only down to 85' now, and the RH is holding steady at 35%... As the temp drops the RH is staying the same, but I know I am actually still pulling more water out.

Tomorrow the weather is supposed to be over 100' so my electric bill is going to be serious this month, but it will be a bad month for the mold.

JR

[JR.]

After a few days pulling gallons of water out of my interior air, I feel a little like Sisyphus. This is MS after all.

As expected the dehumidifier works better at higher room temp, while the RH reading gets artificially low (due to higher temp) and turns off at the 30% min setting.

According to the WWW I can check mold growth by keeping RH < 50% so I'm there...

I wonder if I used the gallons of water I pulled from my air to brew beer with??

Nah.

JR

[emrr]

Dehumidifier extract brew! Or cold press coffee. I see a need to rewind the coil in a nice kitchen safe copper....

[JR.]

yup coffee might be safer because I'd boil that first....

Not sure how green I want to be... Not a very green way to get water.

JR

[JR.]

Ok, as so often life gives us the test, then the lesson. I am learning a bunch about the relationship between humidity and mold. My problem started with a leaky toilet over a decade ago that provided the damp environment in my bathroom floor that allowed the black mold to get entrenched there.

Over the last few years I have cleaned up and out a ton, but for now I am focussed on my bedroom that was still not clear. I recently discovered that my box frame and mattress showed evidence of mold. The mattress only had a few pink spots, but according to my WWW research those pink spots are evidence of black mold. The bottom of my box frame was clearly discolored and infested with mold.

My dehumidifier is still pulling decades of moisture out of my house, but I also notice a daily pattern repeating. I don't run the dehumidifier in my bedroom at night because of the noise and heat, but observe that at night when I turn off and move the dehumidifier, my bedroom is in the low 30"s RH. The next morning when I start it up again the RH is up near 50. So I am clearly breathing (and sweating) new humidity into my bedroom.

Another data point from my research suggested that mold will remain dormant if RH drops below 50% at least once a day, so schools and large office buildings can reduce humidity at night when all the moisture bags are not there, to keep mold in check.

Back to my situation. Connecting a few dots about RH and temperature (and dew point). When I sealed up my bedroom with double insulated storm windows, "and" only heated the bedroom at night (during winter months). The elevated temperature at night (which increases the ability of air to hold moisture) combined with me breathing moisture into the air, raised the moisture content of the air every night. THEN... in the morning when I removed the heat, the now moisture laden air, cooled down and no longer could hold all that extra moisture so like the morning dew it looked for surfaces to release it.

I researched the mechanism for dew and it is not very simple, but physical structures like spider webs are natural dew collectors because of their high surface area to mass ratio, that cause them to lose heat more quickly than other surfaces in the area so they are the coolest thing around when heat is being released. The bottom of my box frame is covered with an open weave cloth, no doubt to facilitate air flow to not trap moisture in, but in my case unintentionally presenting a synthetic faux spider web for moisture to precipitate onto, providing the moisture source for black mold to prosper.

In hindsight I was too clever for my own good, and while a good plan to save energy, I needed to control humidity too. The good news is that the dehumidifier throws heat so in the winter I can use it to good effect. In the summer the extra heat is not so good. I suspect modern homes with central air and heat, already manage humidity, my house is not that clever.
======

My next project to tackle is my refrigerator. I haven't cleaned under and around it for over a decade or more. I believe these usually have a moisture drain tray under them so I expect to find some nastiness behind and under there...

JR

PS: Because of the mold I have recently been thinking of requesting a viking funeral when I die, but instead of burning me in a boat out at sea... burn me inside my house to kill the mold. But since I am not ready to die just yet, I will continue cleaning and cutting off moisture sources for my mold.

[JR.]

For the last couple months I have been been running a dehumidifier to pull excess moisture from my house (to suppress mold). About a month ago as humidity levels dropped indoors and out, the dehumidifier temperature readout just said LO and the RH display appeared high...

A couple weeks ago I bought a cheap humidity meter (claimed 4% accuracy). Indeed the external RH gauge reads 6-12% lower, which agree's with my expectations. Apparently the dehumidifier knows it isn't accurate so warns with the LO.

Since the humidity gauge was cheap ($9) I decided to pick up a second one to place elsewhere in my house. My immediate reaction was not good when the second meter did not agree with the first. RH and temperature were both about 4 points different. I swapped the batteries around and the errors stayed the same... so I left them side by side for a few hours and bingo, after about 4 hours they were within one tick of each other, and close enough for government work.

I hope they engineered these to be accurate after 4 hours and not when first fired up.

JR

[Speedskater]

I hope they engineered these to be accurate after 4 hours and not when first fired up.

That's why audiophiles burn-in their cables for hundreds of hours.

[JR.]

I hope they engineered these to be accurate after 4 hours and not when first fired up.

That's why audiophiles burn-in their cables for hundreds of hours.

There actually is a self-annelaing mechanism for active devices, but not for wire.

Since both the temp and RH were off a similar amount I am suspicious of probably the microprocessor's internal voltage reference. A cheap design is not going to use fancy convertors or even external voltage references. After they got settled in they all agree. Except for the dehumidifier that isn't happy with low humidity which is OK too.

Good enough for me.

JR

[JR.]

As I've mentioned since I sealed up my house tight to reduce energy costs I've noticed humidity/mold issues (actually a leaky toilet started the mold problem).

I have a serious compressor based dehumidifier but it is a PIA to drag it from room to room.

In a "gee whiz that looks interesting" I bought a Peltier based dehumidifier. The rated 28 ounces/day seems marginal but if I can run it at night while I sleep that buys it more time to work.

Well after running it over night I can report that it is not silent but quiet enough that I can sleep with it running.. the water removal is not very impressive. While less than 24 hrs, it pulled about a pint of water. The free standing humidity meter reads above 50%RH so I'll see if it can draw down humidity running all day. Otherwise it's a failed experiment.

One detail I just noticed the sales spec says for spaces up to 2200 "cubic" feet. A casual reading of the spec thinks square feet. 2200 cubic feet is just about my bedroom size, so again marginal.

We'll see but it looks like Peltier technology may disappoint again... I do have several Peltier devices left over from my cooker project, maybe time to repurpose them into a dehumidifier?

JR

[JR.]

I continue to tweak my home heat/cooling for improved efficiency and personal comfort.

To move beyond these updates from a few years ago, the 1kW baseboard resistance unit was marginal to hold temp on cold nights, so I upgraded to 1500W. After I upgraded to a big dog modern heat pump I no longer turn of heat/cooling for my main room at night.

Applying the concept of continuous improvement, this season after permanently installing my blower to suck heated/cooled air from my main room to the back bedroom, I have closed the loop on cybernetic control to operate the blower when my bedroom time of day thermostat is calling for heat. I wired my 1000w and 1500w baseboard units in series (for roughly 600w max). Carrying that concept one step past still working I bought a 1000W @ 240V baseboard unit (125W at 120V) but it didn't draw enough current to keep the thermostat happy. I guess that is a safety feature to protect against loose wiring.

Since that baseboard unit was too small to use in the bedroom I put it into my greenhouse to replace the incandescent light bulbs I was using for heat. the only 125W is marginal but on the coldest recent nights it held the green house to above 59'.

My next attempt was to use a 2500W 240V unit at 120V, making 250W max. This is enough current to keep the thermostat working and maintained thermostat temps with overnights down in the 30s. I have the 3 speed blower set on medium speed so for colder nights I could switch blower to high speed to move more warm air.

===

I am having trouble making sense of the utility bill "nudges" where they compare my power consumption to my neighbors,,,, instead of the normal congrats that I am using less than my neighbors, the last two periods say I am using more... I may have figured it out... one neighbor died about when that comparison suffered and I think her house has been sitting empty since then... I doubt it is being heated while empty.

JR