Dehumidifier in Basement Question

[Jerry1]

Eventually the light bulb went off - I put the dehumidifier on top of a utility shelf next to the basement sink, so the unit is higher than the sink and the hose runs into the sink drain.

Your solution is elegantly simple, however, if you need the dehumidifier in a different location, they make small pumps to handle your situation.

https://www.littlegiant.com/products/condensate-removal-pumps/

 

[Koolau]

I looked at my notes, ours, rated at 50 pints/day (what an odd measure!), cost ~ $200 last year, and uses ~ 550 watts full on. So ~ $.05/hour that it runs.

How much it runs per day is a big variable. As I mentioned upstream, rather than set it to "AUTO" (which, IMO has it cycle too much), I just turn it on to the 4 hour "delay OFF" setting (it has a 2 and 4 hour setting) when I see the RH% creeping up. In humid whether, that might only be 2 or three times a day, sometimes not at all, I haven't really kept track that closely. And we don't need it at all Fall through Spring.

But even at 12 hrs/day for a month, that's ~ $0.60 per day, ~ $18/month. Not far from your number - though electricity was cheaper then, I bet that old unit was far less efficient.

But I don't think ours runs anywhere near 12 hours a day for a full month. I'll try tracking closer this year. Last year was more of a "get it done" year, just so many things to 'tweak' after a move. This year is more of a 2nd pass improvement year.

-ERD50

At 550 watts that would be about $0.20/hour now (less then, of course.) IIRC, I emptied our DH at least twice per day. No idea how much it ran, but it seemed like a lot.

 

[kgtest]

We run the basement dehumidifier continuously from May to end of September, unless we are gone from the house. Upon our return when it's off, the basement always smells musty. A couple of days later, it's fine. We spend a lot of time in our finished walk-out basement because it's comfortably cool in the summer.

Same. Home was built in the 1990. There is a spot to install a sump pump, but never needed one. We run the dehumidifier from May to September. In the winter it's not an issue.

If we didn't run it, it would smell musty. We had one in our old home built in 1962 it was the same issue.

We have a walkout, so some of the basement is under water, and there is a bit of a protected wetland in the back of our property. Neighbors backyard floods on occasion, I elevated my yard so mine doesn't.

 

[marko]

OP here. Help me with the math. My 50 pint per day DH is listed by Energy Star at 1.9L/kwh. My utility charges me .26 / kwh. What is this thing costing to run on a 24 hr day? "Numbers is hard for me"

Specifications
ENERGY STAR Unique ID: 2375302
Brand Name: Midea
Model Name: Dehumidifiers
Model Number: MAD50C1AWS
Dehumidifier Type: Portable Dehumidifier
Dehumidifier Water Removal Capacity
(pints/day): 49.93
Dehumidifier Efficiency (Integrated Energy
Factor - L/kWh): 1.9
Date Available on Market: 2020-12-18
Markets: United States, Canada
ENERGY STAR Certified: Yes
ENERGY STAR Most Efficient: Yes

 

[ERD50]

OP here. Help me with the math. My 50 pint per day DH is listed by Energy Star at 1.9L/kwh. My utility charges me .26 / kwh. What is this thing costing to run on a 24 hr day? "Numbers is hard for me"

Specifications
ENERGY STAR Unique ID: 2375302
Brand Name: Midea
Model Name: Dehumidifiers
Model Number: MAD50C1AWS
Dehumidifier Type: Portable Dehumidifier
Dehumidifier Water Removal Capacity
(pints/day): 49.93
Dehumidifier Efficiency (Integrated Energy
Factor - L/kWh): 1.9
Date Available on Market: 2020-12-18
Markets: United States, Canada
ENERGY STAR Certified: Yes
ENERGY STAR Most Efficient: Yes

It may not be just a math problem. I'm not sure those numbers will get you there. The 50 pints per day is under certain test conditions, I'd assume it is running continuously for that test. It's not clear if the Efficiency rating of 1.9L/kWh is under those same conditions or not.

And we also don't know what you mean by "run on a 24 hr day". If it is set to auto, how much it runs depends on the humidity and size of the area.

What you probably want to know is, how much current or watts it draws when running, and how many hours/day it will run. Then you take the watts (or current * 120V) * hours, divide by 1000 to get kWh. Then multiply kWh times your .26 / kWh rate.

Mine runs ~ 550 watts. So if it is on 8 hrs a day (your mileage *WILL* vary), that is 550*8/1000 = 4.4 kWh. Times your $0.26 = $1.14/day

-ERD50

 

[marko]

I don't have a floor drain, so I was emptying mine via the hose into the sump pump pit. Not ideal, since the pit is only crushed stones over dirt. So that was no doubt throwing some dampness back into the basement.

Eventually the light bulb went off - I put the dehumidifier on top of a utility shelf next to the basement sink, so the unit is higher than the sink and the hose runs into the sink drain.

I almost bought a more expensive one with a built-in drain pump. Then I realized that my furnace/AC combo has a sump/bilge pump so I just routed the DH hose to an extra inlet and presto!

 

[marko]

It may not be just a math problem. I'm not sure those numbers will get you there. The 50 pints per day is under certain test conditions, I'd assume it is running continuously for that test. It's not clear if the Efficiency rating of 1.9L/kWh is under those same conditions or not.

And we also don't know what you mean by "run on a 24 hr day". If it is set to auto, how much it runs depends on the humidity and size of the area.

What you probably want to know is, how much current or watts it draws when running, and how many hours/day it will run. Then you take the watts (or current * 120V) * hours, divide by 1000 to get kWh. Then multiply kWh times your .26 / kWh rate.

Mine runs ~ 550 watts. So if it is on 8 hrs a day (your mileage *WILL* vary), that is 550*8/1000 = 4.4 kWh. Times your $0.26 = $1.14/day

-ERD50

Thanks ERD50! Mine seems to run almost all the time. I caught it stopped only once so far and it restarted within 30 seconds. Following your numbers I could be looking at about $120 a month but we should only need it from June to September. Based on that however, I just increased the RH to 50 from 45

 

[Koolau]

Thanks ERD50! Mine seems to run almost all the time. I caught it stopped only once so far and it restarted within 30 seconds. Following your numbers I could be looking at about $120 a month but we should only need it from June to September. Based on that however, I just increased the RH to 50 from 45

At that cost, it might be worth dealing with the moisture issue. There are companies that do that. YMMV

 

[RetiredAt55.5]

Mine seems to run almost all the time. I caught it stopped only once so far and it restarted within 30 seconds.

The last 2 dehumidifiers I got do the same thing - they seem to "run" almost all the time. If you hang around the room long enough, you can hear it shut off, but then it starts up again within a minute. Both units had the Energy Star sticker on them, and my electric utility gave me a rebate check for them being more energy efficient. The units I had prior to that never ran continuously.

I think what's going on is that the fan is running almost all the time. The compressor cycles on and off as needed to keep the desired humidity level. I've been too lazy to hook up a watt usage meter to the outlet to confirm this. I will say that when I got some water in my basement, I definitely noticed a bump in the electric bill so I have to assume the compressor was kicking in more often.

 

[JoeWras]

The last 2 dehumidifiers I got do the same thing - they seem to "run" almost all the time. If you hang around the room long enough, you can hear it shut off, but then it starts up again within a minute. Both units had the Energy Star sticker on them, and my electric utility gave me a rebate check for them being more energy efficient. The units I had prior to that never ran continuously.

I think what's going on is that the fan is running almost all the time. The compressor cycles on and off as needed to keep the desired humidity level. I've been too lazy to hook up a watt usage meter to the outlet to confirm this. I will say that when I got some water in my basement, I definitely noticed a bump in the electric bill so I have to assume the compressor was kicking in more often.

Yes. My new (rather 6 years old) dehumidifier has the fan run nearly continuously. The compressor only comes on occasionally. I estimate it is adding about $15 per month judging by my billing history.

I was surprised that an EnergyStar device would have a fan run all the time, even if it is a fairly low draw.

I'll put my Kill A Watt on it today and get some numbers.

 

[RetiredAt55.5]

Yes. My new (rather 6 years old) dehumidifier has the fan run nearly continuously. The compressor only comes on occasionally. I estimate it is adding about $15 per month judging by my billing history.

I was surprised that an EnergyStar device would have a fan run all the time, even if it is a fairly low draw.

I'll put my Kill A Watt on it today and get some numbers.

I got off my duff and plugged in my Kill A Watt.

My 3 year old 70 pint Frigidaire uses about 74 watts when just the fan is running, and between 570 and 590 when the compressor is running.

 

[finnski1]

I got off my duff and plugged in my Kill A Watt.

My 3 year old 70 pint Frigidaire uses about 74 watts when just the fan is running, and between 570 and 590 when the compressor is running.

Yeah I really need to get one of those Kill A Watt meters.

 

[ERD50]

Yes. My new (rather 6 years old) dehumidifier has the fan run nearly continuously. The compressor only comes on occasionally. I estimate it is adding about $15 per month judging by my billing history.

I was surprised that an EnergyStar device would have a fan run all the time, even if it is a fairly low draw.

I'll put my Kill A Watt on it today and get some numbers.

I don't know if the test conditions are made public.

(edit/add -oops, thought I found it - water heaters instead, will try again later!

But that might make the constant fan a small issue. They'd probably need a separate relay/control for it, you want the fan to run a while after the compressor shuts off, to get that last bit of cool/de-humidification out, and maybe to keep it from freezing.

Plus, if you don't circulate the air, that auto/humidistat is going to react to the local humidity within a few feet of the unit. Keeping the fan running helps to keep that air moving through the whole area. I considered running another big box fan to move more air around - I do see several points delta from one end of the basement to the other.

-ERD50

 

[JoeWras]

I got off my duff and plugged in my Kill A Watt.

My 3 year old 70 pint Frigidaire uses about 74 watts when just the fan is running, and between 570 and 590 when the compressor is running.

Got off my duff and checked my 6 year old LG, smaller unit:
- 50 watts fan (or 30 on low speed, which I don't use)
- 500 watts with compressor

I'm looking up my Kill-A-Watt instructions now to configure it for our latest rates and let it run a day. I've never done that before. In this case it will come in handy since the compressor's duty cycle is unknown since I don't sit there watching it. The basement is in a "typical" cycle of humidity so I can estimate a season's cost from a day or two.

EDIT: this should be easy and is really how the Kill-A-Watt should be used. Plug it in a few days and let it do the math. I've typically only used it for instantaneous measurements. I'll get back to ya'll in a few days on what I find.

 

[JoeWras]

Ran the Kill-A-Watt for a day during this humid period, with rain, and it is calculating about $14 per month. My dehumidifier is medium in size and the area is about 350 sq. ft. I run it 6 months per year. This is probably worst case scenario because it is cool enough such that the A/C is not running right now, which would help in the dehumidifying.

I'm OK with saving the house structure and our stuff for $100 per year.

 

[marko]

Ran the Kill-A-Watt for a day during this humid period, with rain, and it is calculating about $14 per month. My dehumidifier is medium in size and the area is about 350 sq. ft. I run it 6 months per year. This is probably worst case scenario because it is cool enough such that the A/C is not running right now, which would help in the dehumidifying.

I'm OK with saving the house structure and our stuff for $100 per year.

My electric bill is coming out in a few days and I keep meticulous records. Assuming last year's electrical usage is fairly close to this year, I should be able to do a May '21/May '22 comparison as the DH is the only new appliance running. I'll let y'all know.

 

[ERD50]

My electric bill is coming out in a few days and I keep meticulous records. Assuming last year's electrical usage is fairly close to this year, I should be able to do a May '21/May '22 comparison as the DH is the only new appliance running. I'll let y'all know.

Get a Kill-a-Watt meter (or equivalent). I put little faith in year-year comparisons, far too many variables.

-ERD50

 

[ERD50]

Update to below - the govt docs were very difficult to follow, all sorts of cross references that had me going in circles. I found some talks about how the performance numbers were changed ~ 2019 - previously, all dehumidifiers were tested at 80F, it was decided that "portable" units were more likely to be in a basement, so they started testing at 65F (which gives a much lower capacity figure, cold air holds less moisture), and built in "whole house" units at, I think 74F?

But those same sources didn't say what the humidity level they tested at was, geez, give me the number, it's pretty important! Finally found a few sources that mentioned 60% RH, which makes sense, I have no idea why this was so hard to find.

So now I'm going to check mine over a 4 hour cycle - humidity average will be below 60%, but I can probably figure a reasonable allowance for that.

https://www.sylvane.com/blog/new-dehumidifier-testing-standards-for-2020/

-ERD50

I don't know if the test conditions are made public.

(edit/add -oops, thought I found it - water heaters instead, will try again later!

But that might make the constant fan a small issue. They'd probably need a separate relay/control for it, you want the fan to run a while after the compressor shuts off, to get that last bit of cool/de-humidification out, and maybe to keep it from freezing.

Plus, if you don't circulate the air, that auto/humidistat is going to react to the local humidity within a few feet of the unit. Keeping the fan running helps to keep that air moving through the whole area. I considered running another big box fan to move more air around - I do see several points delta from one end of the basement to the other.

-ERD50

 

[marko]

Get a Kill-a-Watt meter (or equivalent). I put little faith in year-year comparisons, far too many variables.

-ERD50

Yeah, I will; they’re cheap enough. But the DH is the only thing I'd have use for measuring. While I hate the term "it is what it is ", I'm not sure I'd alter my use regardless the (within reason) extra cost, but it would be good to know. I just like understanding "the envelope" of everything.

 

[ERD50]

Update: Constant 4 HR ON vs Auto Efficiency

I mentioned earlier that when I leave my De-H in "Auto" mode (humidistat controlled), it cycles ON/OFF pretty often , and I didn't think that could be good for efficiency. The other day, I realized that it would not be so hard to measure this (harder to describe):

A) Wait for basement to hit 60% RH. Drain the tank, plug De-H into my Kill-a-Watt, and reset the kWh reading. Set it for a 4 HR constant ON cycle.

B) At the end of that cycle, record the kWh usage, and measure the water in the tank. I got 2.18 kWh and 3.75 Quarts.

Later, when the RH gets back to 60%, repeat that with the "Auto Mode" set to 60% (it roughly turns on @ 60% and runs down to 55% and turns off). I waited until it started cycling (about 1 hour), and then reset and drained. I let it run until the kWh meter read close to 2.18, then did the math for kWh/Quart. BTW, when I caught it, it was running ON for 19 minutes, OFF for 5 Minutes, and that was near the start - they might have got a bit shorter as time went on.

I happened to catch it almost exactly, at 2.20 kWh. I drained it, and got only 3.25 Quarts.

2.18/3.75 = 0.581 kWh/Q running "ON", vs
2.20/3.25 = 0.677 kWh/Q running "AUTO" ~ 16% more electricity per unit of moisture removed.

I might repeat that a few times, not everything is that well controlled, temperature varies a bit, and while humidity isn't constant in either case (more constant with the "AUTO" mode), in the end, (within reason), it's really the amount of moisture removed that I'm focused on. If I go a little further with the 4HR setting, fine, it's just that much longer before I need to turn it on again.

But the savings isn't tiny, and I would think constant ON would be better than the ON/OFF cycles, and longer total run time for AUTO's lower efficiency.

Obviously, this only makes sense for a case like mine where I can easily check the humidity several times a day (I can see the humidistat at the bottom of the stairs from the door to the basement), and it's convenient to go hit the 4HR button. And if I'm going to be out and can't watch it, I'll just set it to AUTO, not a deal breaker.

But it's considerable enough that I'll continue to do the 4 HR cycles when needed.

Oh, and that 3.75Q in 4 hours is actually pretty close to the stated 50 pints per day specification - within a reasonable range of error for my level of control of the conditions.

-ERD50

 

[marko]

So my electric bill came in today. I know that this method is not accurate at all but my May '21 to May '22 comparison shows that my dollar cost increased by $38 and an increase of 158kwh. The new dehumidifier ran almost nonstop from May 2nd to the end of May. It's the only new appliance I've added.

In general, my month to month comparisons show a fairly consistent usage, so my "windage" says that for $40 a month for six months, it's worth it.

 

[Go-NoGo]

My basement also runs damp in the summer months and the dehumidifier I purchased tended to run all day. The compressor turns off when it reaches the desired RH setting, but the fan continues to run. it does NOT have a cycle setting.

Rather than have it run 24 hours a day, I repurposed a "smart plug" - created a schedule that runs it for 2 hours followed by a rest period of 4 hours. Total run time now is 8 hours a day and the air in my basement is dry.

If it is a particularly humid day I just ask Alexa to run the dehumidifier from my living room.