Okay, that makes sense.
If only one small spot is cooled at a time and frosts up then I can see how the whole thing could eventually freeze.
Dehumidifier that doesn't...
- Thread starter wayneh
- Start date
If only one small spot is cooled at a time and frosts up then I can see how the whole thing could eventually freeze.
My personal opinion is summarized in one word: market
The market for AC units is probably far larger than for DH.
Also, since a DH will always be contained entirely indoors, the units need to be smaller and slicker than ACs, and the only way to accomplish that is by making the components more compact by sacrificing robustness and, inevitably, reliability.
KeepItSimpleStupid
- Joined Mar 4, 2014
- 5,088
I have a de-humidifier that's close to 60 years old. Granted, it's not used much. All metal with a plastic pan, replaced long ago.
I'd say three services on 60 years;
1. Thorough cleaning
2. repaint. That took weeks to do it right. The first color I didn't like.
3. New power cord. That was a very difficult procedure. Clearances were pretty tight. The only thing that made sense was a molded power cord because it fit into an open-sided D shaped hole. I visited a vacuum repair store for the part.
Next, the problem was fixing the "design issue" and extending the wires. That was accomplished with a fiberglass braiding and Teflon insulated wires to remove the effects of vibration.
The de-humidifier does not shut off if the resovour is full. Adding a shut off would be hard.
The control isn't the best. I would add a (About a $140) stand-alone outlet like dehumidifier/heater controller if it was that important.
it's generally used to remove water from basement water issues.
I'd say three services on 60 years;
1. Thorough cleaning
2. repaint. That took weeks to do it right. The first color I didn't like.
3. New power cord. That was a very difficult procedure. Clearances were pretty tight. The only thing that made sense was a molded power cord because it fit into an open-sided D shaped hole. I visited a vacuum repair store for the part.
Next, the problem was fixing the "design issue" and extending the wires. That was accomplished with a fiberglass braiding and Teflon insulated wires to remove the effects of vibration.
The de-humidifier does not shut off if the resovour is full. Adding a shut off would be hard.
The control isn't the best. I would add a (About a $140) stand-alone outlet like dehumidifier/heater controller if it was that important.
it's generally used to remove water from basement water issues.
I added a garden hose bibb and hose to my drain pan. It then goes into a floor drain.
FWIW, the newer Frigidaire DH models come with a hose bib built in, behind a little access door. Very easy to run continuously. The new A/C that should be delivered to me today relies on collected condensate to help cool the condenser, so by design the water doesn't drain out. It gets slung out through the coils. I'll have to modify that!
Good news so far: 14 cups in the first 325 minutes, which works out to 1.29 pints per hour or 31 pints per day. That's more or less as expected for a unit this small. Frigidaire quotes 1.1 pts/hr for my unit.
Observations so far:
• The plug has an integral GFCI in it. Never saw that on a DH but seems like a good idea.
• The fan motor is WAY bigger than in a DH. Makes sense if it has to circulate in-house air while also exhausting heat out the back. But wait, there may be a separate motor for the in-house circulation.
• The condenser coil is larger than in a DH, even one with twice the capacity.
• The compressor looks more-or-less like the one I just hauled away, in terms of physical volume.
• The lack of a nice plastic shell, like the DH, is notable. No wheels, no handles, minimal interface. The condenser coil is wide open and easily damaged.
• I specifically bough a unit with mechanical controls, because that's cheaper and I intend to control it with my own humidistat.
• Between the shell, controls and so on, I can definitely see that you pay for these things in a dehumidifier. I can't imagine how you could make this window A/C any simpler.
I'll get pictures of my handiwork tomorrow.
Observations so far:
• The plug has an integral GFCI in it. Never saw that on a DH but seems like a good idea.
• The fan motor is WAY bigger than in a DH. Makes sense if it has to circulate in-house air while also exhausting heat out the back. But wait, there may be a separate motor for the in-house circulation.
• The condenser coil is larger than in a DH, even one with twice the capacity.
• The compressor looks more-or-less like the one I just hauled away, in terms of physical volume.
• The lack of a nice plastic shell, like the DH, is notable. No wheels, no handles, minimal interface. The condenser coil is wide open and easily damaged.
• I specifically bough a unit with mechanical controls, because that's cheaper and I intend to control it with my own humidistat.
• Between the shell, controls and so on, I can definitely see that you pay for these things in a dehumidifier. I can't imagine how you could make this window A/C any simpler.
I'll get pictures of my handiwork tomorrow.
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From my hole-drilling thread:
Both of the heat exchangers on my new A/C are bigger than those on the dehumidifier I just hauled off. The limiting factor on efficiency of any refrigeration device is the effectiveness of the heat exchangers. Infinitely large heat exchangers would allow you to approach the thermodynamic limits of vapor recompression air conditioning. So, my initial impression is that the A/C unit may be more efficient than the dehumidifier, because it has better heat exchangers.
The condenser heat exchanger of an A/C is designed to operate outside, potentially in direct sunlight on a 100+°F day. My basement is dark and never gets above 70°F, so the condenser coil and its fan may be oversized for my application. Not a bad thing.
My A/C has two indoor fan speeds, and I'm using the lower one. I think they oversized the fan to help cool a room quickly and probably to blow some air on the user, giving some cooling. That's not really important in my application. I think the lower speed may favor dehumidification.
I went down this morning to measure how much water had been pulled out overnight. The reservoir was empty. WTF?! The wife had gotten there first and emptied it. Sheesh. Why? "Because I didn't want it to overflow." It's sitting on the floor drain.
Exactly. Every watt consumed by the repurposed A/C or a dehumidifier ends up in the room. So any difference - at a given humidity removal rate - is due to slight efficiency differences.
Both of the heat exchangers on my new A/C are bigger than those on the dehumidifier I just hauled off. The limiting factor on efficiency of any refrigeration device is the effectiveness of the heat exchangers. Infinitely large heat exchangers would allow you to approach the thermodynamic limits of vapor recompression air conditioning. So, my initial impression is that the A/C unit may be more efficient than the dehumidifier, because it has better heat exchangers.
The condenser heat exchanger of an A/C is designed to operate outside, potentially in direct sunlight on a 100+°F day. My basement is dark and never gets above 70°F, so the condenser coil and its fan may be oversized for my application. Not a bad thing.
My A/C has two indoor fan speeds, and I'm using the lower one. I think they oversized the fan to help cool a room quickly and probably to blow some air on the user, giving some cooling. That's not really important in my application. I think the lower speed may favor dehumidification.
I went down this morning to measure how much water had been pulled out overnight. The reservoir was empty. WTF?! The wife had gotten there first and emptied it. Sheesh. Why? "Because I didn't want it to overflow." It's sitting on the floor drain.
I think our spouses read the same book on "how to be a wife"I went down this morning to measure how much water had been pulled out overnight. The reservoir was empty. WTF?! The wife had gotten there first and emptied it. Sheesh. Why? "Because I didn't want it to overflow." It's sitting on the floor drain.
Here's the little stand I built to hold the new A/C. All scrap wood I had on hand, most of it – particularly the leg wood – is treated. Should last forever in the basement.
Hole, what hole?
It's coming together. I'm directing the warm air at my water heaters, one visible on the right.
Next up: Adding the humidistat and control panel.
Hole, what hole?
It's coming together. I'm directing the warm air at my water heaters, one visible on the right.
Next up: Adding the humidistat and control panel.
Attachments
Is it quiet? Our latest dehumidifier sounds like a jet engine.
I wouldn't describe it as quiet. The specs at Frigidaire claim it's 54dB, same as their dehumidifiers. But that may be indoors with half of it hanging out the window. On the lower fan speed I'd say it's a little noisier (and blowing more air) than the dehumidifier on high fan. Maybe worse is the type of noise. The air blowing is one thing but I also hear a 60Hz cricket chirp like sound from the compressor. Not bad, not loud, but I don't think I'd want it in my bedroom.
BTW, fresh data: 33 cups removed in the last 14 hours, or 28.3 pints/day. The basement is getting drier.
BTW, fresh data: 33 cups removed in the last 14 hours, or 28.3 pints/day. The basement is getting drier.
Good data. How many amps?
It draws less than 400W, so the heating of the basement is minimal. It does produce a warm spot and a cooler area, since it blows in opposite directions.
The Frigidaire specs say it's 400W, but I'm pretty sure I read a post from someone that used a Kil-A-Watt on it and read 360W or something like that.
30 ppd for 400W is over 3 pints per kWh, which is very good. Most dehumidifier models rate in the range of 1.5-3 pints per kWh, with the bigger machines at the higher end and small ones like mine at the lower end. My basement is probably not at the standard conditions for testing, so I'm not claiming any unexpected performance, just that it's working well.
The Frigidaire specs say it's 400W, but I'm pretty sure I read a post from someone that used a Kil-A-Watt on it and read 360W or something like that.
30 ppd for 400W is over 3 pints per kWh, which is very good. Most dehumidifier models rate in the range of 1.5-3 pints per kWh, with the bigger machines at the higher end and small ones like mine at the lower end. My basement is probably not at the standard conditions for testing, so I'm not claiming any unexpected performance, just that it's working well.
We were getting a full bucket of water from out dehumidifier every 24 hours. Then we painted the cinder-block walls with Dry-lok paint and that cut the water collection to about one bucket every 2 to 3 days. I concluded that a lot of moisture is 'transpiration' / wicking / what ever you want to call it through the brick. Naturally, we always kept our door to the basement closed so we are not dehumidifying the warm air that migrates down there. Radon levels remain low, luckily (even with minimal circulation).
Here's my Frankenstein, 100% from repurposed partisan supplies. The purpose of this beast is to place my new A/C under humidistat control instead of the crude mechanical thermostat control it came with. I've set it to "max cool" and low fan. This Frankenstein controls power to the A/C, whose controls are unaltered.
The PCB was taken from the old dehumidifier, now it's screwed up under the top of the little stand I built . That's a standard outlet box on the left. The thing on the ribbon cable is the humidity sensor. The coil-icing sensor is the coiled up black cable upper right. The pan-full sensor snap switch connects to the smaller open connector on the lower edge of the PCB. I've just taped it closed. (Not shown. It's a NO switch held closed by the float until water pivots the float and allows the switch to open.) The larger empty connector was for the dehumidifier's 2-speed fan. The black relay box on far left of the PCB controlled power to the dehumidifier's compressor. Now it powers up the outlet box which the A/C is plugged into.
The little dangling LED board used to light the red LED when the water pan got full, green when all was well. I'll probably mount it and the sensor so they're not just dangling. Note how the dehumidifier control panel is now screwed to the face of the little table. Kinda proud of that hack.
The PCB was taken from the old dehumidifier, now it's screwed up under the top of the little stand I built . That's a standard outlet box on the left. The thing on the ribbon cable is the humidity sensor. The coil-icing sensor is the coiled up black cable upper right. The pan-full sensor snap switch connects to the smaller open connector on the lower edge of the PCB. I've just taped it closed. (Not shown. It's a NO switch held closed by the float until water pivots the float and allows the switch to open.) The larger empty connector was for the dehumidifier's 2-speed fan. The black relay box on far left of the PCB controlled power to the dehumidifier's compressor. Now it powers up the outlet box which the A/C is plugged into.
The little dangling LED board used to light the red LED when the water pan got full, green when all was well. I'll probably mount it and the sensor so they're not just dangling. Note how the dehumidifier control panel is now screwed to the face of the little table. Kinda proud of that hack.
Some years ago I picked up 6 slightly used commercial units from a college auction for something like $20 for the set. They worked great but dang, it would be hard to convince anyone that they didn't use tiny diesel engines for the compressors.
I gave two of them to my buddies and they have been in their basements running near nonstop for close to a decade now. Never did get quieter with age either.
Fresh data: 38 cups in the last 22 hours. That's 20.7 ppd, down from the initial value closer to 30.
The humidity in my basement has fallen to the set point of 45% RH, so it's possible the A/C has been not been running continuously for those 22 hours.
But I also suspect that the A/C is less able to pull water out at lower humidity, compared to a dehumidifier. Maybe the A/C coil doesn't get quite as cool as a genuine dehumidifier? It would make sense. A DH should be designed to run in a basement and needs a cooler coil to wring out the water even when the humidity is below 50%. An A/C is designed to move as many BTUs as possible from one side to the other, with generally warmer air.
Still, I'm happy with the experiment so far. Just gotta see how things look 10 years from now.
The humidity in my basement has fallen to the set point of 45% RH, so it's possible the A/C has been not been running continuously for those 22 hours.
But I also suspect that the A/C is less able to pull water out at lower humidity, compared to a dehumidifier. Maybe the A/C coil doesn't get quite as cool as a genuine dehumidifier? It would make sense. A DH should be designed to run in a basement and needs a cooler coil to wring out the water even when the humidity is below 50%. An A/C is designed to move as many BTUs as possible from one side to the other, with generally warmer air.
Still, I'm happy with the experiment so far. Just gotta see how things look 10 years from now.
