Dehumidifier Face-Off

[TromboneAl]

We have two dehumidifiers but now only need one. I wanted to figure out which is more efficient. The idea is to compare (1) how much water they remove from the air and (2) how much electricity they use.

In one corner, we have a Sears beast that we bought fifteen years ago at a garage sale and which has been running every day.

In the other corner, a sleek Frigidaire that we've had for two years.

Step 1: I ran them both, side by side, on continuous-on mode for a few hours. The beast removed 850 ml of water from the air. The sleek Frigidaire removed a piddling 10 ml.

No point in measuring power usage. Do you think the Frigidaire is broken?

 

[Spock]

clean the fins.

 

[Fishingmn]

There was an article in the Minneapolis Star Tribune a couple days ago saying new dehumidifiers last 1-2 years these days and old ones last for a long time.

 

[travelover]

......... Do you think the Frigidaire is broken?

Sumpin' ain't right. There should not be that big of a difference. Could be blocked air flow or maybe the Frigidaire is not getting cold enough to condense the water vapor.

 

[Lewis Clark]

Is it possible that the dry exhaust from the Sears unit became the input into the Frigidaire unit? Possible if they are sitting side by side.

I'd try re-running the test with both units on different sides of the same room. Then switch their locations and run the test again to ensure room airflow patterns are not affecting the results.

 

[Sunset]

Or the sensor on the one not working well is off, set it to max and see if it gets more water.

 

[JoeWras]

Is it possible that the dry exhaust from the Sears unit became the input into the Frigidaire unit? Possible if they are sitting side by side.

I'd try re-running the test with both units on different sides of the same room. Then switch their locations and run the test again to ensure room airflow patterns are not affecting the results.

+1

Your "beast" likely has a mechanical humidistat that is dumb, maybe even stuck on. If not stuck, it will come on immediately to its setting. It is gonna be "on" a lot and draw power like nuts.

The newer dehumidifiers have some electronic controls that back off the usage of the compressor unless the humidity reading is above the set point for quite some time. This is how it can get an "energy star" rating. I think this is technically called a "duty cycle damper" or some such important engineering sounding name.

So if The Beast is cycling some dry air at your Newbie, the Newbie's controls will see "dry air is around, let me wait until it is really humid to turn on."

Just a guess. Test them one at a time in isolation. Put a Kill-A-Watt or similar when testing.

I have a '91 model Beast that works like nuts, but draws like nuts too. I'm quite pleased with my 3 year old LG model. It has been reliable and although the fan runs a lot, most of the time the compressor is not on. That's half the battle anyway -- keeping the air stirred up in the damp-ish basement.

 

[target2019]

We have two dehumidifiers but now only need one. I wanted to figure out which is more efficient. The idea is to compare (1) how much water they remove from the air and (2) how much electricity they use.

In one corner, we have a Sears beast that we bought fifteen years ago at a garage sale and which has been running every day.

In the other corner, a sleek Frigidaire that we've had for two years.

Step 1: I ran them both, side by side, on continuous-on mode for a few hours. The beast removed 850 ml of water from the air. The sleek Frigidaire removed a piddling 10 ml.

No point in measuring power usage. Do you think the Frigidaire is broken?

If right up against each other, that would have some effect.

 

[target2019]

There was an article in the Minneapolis Star Tribune a couple days ago saying new dehumidifiers last 1-2 years these days and old ones last for a long time.

That has been my experience. For $200, you get 2 years, hopefully.

 

[Breedlove]

Turn the A/C on Dehumidify

 

[travelover]

Turn the A/C on Dehumidify

I don't think Al has AC - he is on the NW coast.

 

[RobbieB]

10 ml? That's just a water mark. Yup, something is not working on that one.

 

[TromboneAl]

Turn the A/C on Dehumidify

I've heard of this A/C thing.

------

Yeah, I'm gonna run the test again, but this time I'll run the shower and get it nice and humid first. They weren't feeding into each other, but I do think the new one was thinking that it wasn't humid enough to go to work.

I'm running the new one in there right now, and it's definitely pulling water from the air.

 

[TromboneAl]

Round Two

Well, I tested them again, and it seems that the old Kenmore dehumidifier is much better and more efficient.

This time I separated by about four feet and made sure that their exhausts were pointed away from each other. I also took a long shower, soaked a towel, and put standing water in the bathtub.

The old Kenmore removed 500 ml from the air. The new Frigidaire removed 50 ml.

I used a Kill-a-watt to measure their power usage:

Sears: .88 kWh in 1.75 hours = .50 kWh/hour
Frigidaire: .33 kWh in .75 hours = .44 kWh/hour

I have trouble believing these results unless the Frigidaire is not working properly.

 

[38Chevy454]

Well, I tested them again, and it seems that the old Kenmore dehumidifier is much better and more efficient.

This time I separated by about four feet and made sure that their exhausts were pointed away from each other. I also took a long shower, soaked a towel, and put standing water in the bathtub.

The old Kenmore removed 500 ml from the air. The new Frigidaire removed 50 ml.

I used a Kill-a-watt to measure their power usage:

Sears: .88 kWh in 1.75 hours = .50 kWh/hour
Frigidaire: .33 kWh in .75 hours = .44 kWh/hour

I have trouble believing these results unless the Frigidaire is not working properly.

Just an engineer's technicality, in this post you are actually getting to efficiency. In the previous posts you were mentioning about the effectiveness of water removal. The Frigidaire is less energy use, but less efficient overall since it removes less water.


I would keep the old Sears unit.

 

[ransil]

I just got a new Frigidaire in the mail thursday, replaced under warranty, the other one lasted 2 years.

 

[Sunset]

I just got a new Frigidaire in the mail thursday, replaced under warranty, the other one lasted 2 years.

You must have a large mailbox !!

 

[target2019]

I've had 6 or more humidifiers, over a long period. I do have a Frigidaire model. In actual operation, I suspect your Frigidaire wins.
In any event keep both. One is gonna breakdown.
Is this used in a basement?

 

[JoeWras]

When my old "beast" humidistat stuck, I just put it on a heavy duty timer to only run a few hours a day. Although not optimal, it seems to be a decent compromise to extract the humidity, yet not burn up excessive power.

 

[Badger]

It makes a difference what you set the Frigidaire for humidity level. The beast that is older than 15yrs may be running to extract down to a lower humidity. Also check that the Frigidaire is not icing up. The Frigidaire is one of the better rated dehumidifiers.


Cheers!

 

[TromboneAl]

I set them both for continuous running.

I'm having trouble believing it, but I can't argue with the results: the old beast sucking ten times the amount of water from the air.

Maybe I'll let each work on its own for a week and measure the ml/kWh.

 

[ERD50]

...

The old Kenmore removed 500 ml from the air. The new Frigidaire removed 50 ml.
...

I have trouble believing these results unless the Frigidaire is not working properly.

It seems obvious it's not working properly. Only 1/10th the water removed as the other? It's dead I tell you!

Well, maybe not dead, but not running right. Somethings just plain wrong.

If the top speed of your car was 10 mph, would you ask questions about mpg, or kWh/mile? No, you'd get it fixed!

-ERD50

 

[target2019]

Fan CFM is not equal in both machines, is it?

 

[ERD50]

From your link, the Frigidaire is rated at 70 PINTS per day. That is 33,122.4 mL per day. That's 1,380 mL per hour.

So in "a few hours"(?) you should be in that ballpark. Now, maybe your conditions don't match the test conditions used for dehumidifiers, but you are more than 2 orders of magnitude out of the ballpark.

The Frigidaire is not working properly. Period. No further testing required.

-ERD50

 

[NW-Bound]

The Frigidaire is not working properly. Period. No further testing required.

Ummm... Yes, it's dead, Jim.

But someone technically inclined would ask "What failed? What is the failure mode here?"

PS. Because the unit still draws 440W on the average, the compressor must still be running. So, it is likely that it has lost Freon and is not able to cool the evaporator enough to condense the moisture. A temperature measurement of the evaporator and the condenser will quickly confirm this.