Electric Bill Enigma: Newsletter Challenge (February 2018)

The bill includes more than the 30 day average billing period, due to initiation of a new customer...or if they are running the dehumidifier they might have water leaking into the basement, or the humidifier is not being properly drained...

wet wire under slab?

electric heat?

moved into big musty house?

lots of coffee brewing?

the people under the stairs?

It's the little green green men down the back of the garden.......they could be either:

1. Leprechauns

or

2. Gremlins

I have them......my electricity bill for three months (summer quarter) was AUS$1 500 (US$1 162) also I do have an 8m x 4m, or 32 000 litre swimming pool (unheated), but, the pump runs most of the summer months, but, in South Australia we have one of the highest electrical tariffs (the tariffs changes on 5, yes FIVE minute cycles) in the world.......all thanks to the government for selling all our suppliers to Chinese companies......I say nothing!!!!

Just on those tariffs.......during one our last heat waves, I think that they said for one (probably more) 5 minute segment they were charging AUS$10 000/Mw

"Cheaper at half the price"......as the saying goes.......I'll take it!!!!

I would suspect it has to do with the furnace. It is December, possibly filters need changed or cold air return is blocked. I am guessing the furnace is running more than it needs to.

Trying to de-humidify the Earth is a Sisyphean task.

I'd say to have a look at the vapor barrier, but good luck with that

Yes, that makes sense!

I have experience of fridge dryers for compressed air. They have to cut off at a point above freezing (to prevent ice building up in side that will stop the air flow) if not, the fridge runs consuming power - but doing nothing useful.

In any case, with a room dehumidifier, the bulk of the water vapour is removed at the higher temperatures, and nothing much is gained by running it a very low temperatures.

The best indication I find is to collect the condensate (in a bucket say) to keep an eye on how much water is dumped - which becomes progressively less over time as the building dies out.

And the point about 'estimated' readings to calculate a bill is valid.

In my case I have an empty property - and has been for 3 years. The meter reading has been exactly the same - ie, zero consumption. But I keep getting bills (direct debits) based on an 'estimate' for the average family of similar properties in the area "...zero must be wrong!.. is the smart-arse reply...you will get a credit next month..."

So the OP might be a victim of this sort of practice.... just a guess.

This is a challenge?

Either the dehumidifier is using the extra energy, or it's a trick question!

"When the electric bill arrives a month later it is much higher than expected."

Doorman changed their front door for one with a higher letter box.

A "small" dehumidifier shouldn't be more than ¼ kW, so, even if they put it on full power 100% of the time it would come to less than 200 kWh per month.

So I don't believe the problem is the power used by the new appliance.

Question says thee bill is for several hundred kWh more than expected. I think you just proved that is the culprit.

The Watt is a unit of power, not energy, so can't correspond to any specific quantity of water removed. It could correspond to a rate of water removal, such as liters or pints per day.

This (very questionable) 2018 table, seen today on a dehumidifier review site (www.bestdehumidifiersguide.com) indicates much lower power ratings:

81.2 Watts (the highest power unit tested) corresponds to only 2kWh per day, or 60 kWh per month, not "hundreds of dollars" for a month.

BUT, the first spec sheet I found was for an LG LD451EGL, which is rated at 45 pints per day, and it specifies 590 watts. Since the larger home units remove 70 pints per day, this could be considered a "small" dehumidifier. 590 W 24/7 corresponds to 425 kWh per month.

Even at a high rate of $0.25/kWh, that would be $106/month; still not what I'd call "hundreds of dollars".

The "Energy Star 2.0" ratings indicate a minimum of 1.5 liters/kWh of energy for medium sized dehumidifiers. 45 pints per day would be ≈21 liters per day, and would thus require ≈14kWh per day, or 422 kWh per month, which corresponds quite well to the LG data.

The large discrepancy between the above table, from a supposedly independent testing agency, and the actual rated power of the one spec sheet seen and the agreement of that with the Energy Star data, seem to indicate some unscientific use of data...

I saw no clues to other possible energy drains in the original challenge; I'll be interested to see the answer...

Hopefully, I'll go check out one or more actual units today...

Yes I guess small is a relative term...I have a 'small' dehumidifier and have noticed the difference in my electric bill when it runs a lot....I usually only run it on rainy days when the humidity is high....the higher the humidity the better it works, I only run it down to 50%, and not very long there....

...but in a basement it shouldn't run that long, it's a sealed room...unless there is water seeping into the space from some source, or they have the humidity set point set really low....the dehumidifier must be drained properly to remove the condensate water from the space...then again they might have a non-vented dryer and washing machine in the basement, or an extra bathroom that gets a lot of use....700 watts can create several hundred kw in a month running continuously, 7kw every 10 hrs...times 30 days = 210kw

..then again there could be a security deposit included in the first months bill...this sometimes happens if previous inhabitants of that property have left the property without paying the final electric bill, or were late with the payment often....the previous owner could have been on some bill averaging program and the monthly electric charges were levelized, or their personal electric usage was much lower than average, some people don't use a lot of electricity....my electric bill is always higher than average...this new house might not be as well insulated as their old house, or they might have more family members living at home....when comparing two different family's electric bill, you are comparing apples and oranges...

Interesting that your unit uses only 6.3 Amps.

I just checked in the local big box store. They have 30, 50, and 70 pint GE™ dehumidifiers, all rated at 115V 15A. This is the only numeric indication of energy use on the outside of the box, and there were no open boxes to check the device labels. I do believe I remember seeing the Energy Star emblem, but it was not on the same box face with the power label (this happens to be from the 30 pint box, but they were all the same):

Since they all use 15 Amps, I presume they all use the same mechanism. Presumably the larger units have larger radiators and of course larger storage chambers.

If the unit is rated for 255W based on normal appliance rating, then it consumes 6.12 KWH per day or 189.7 KWH for a 31 day month. I don't know whether to class 189.7 as several hundred, but depending on the sticker shock from the bill, the customer may be over perceiving it a bit.

Second adder is that the power companies typically are actually billing for VAR rather than watts and the appliance will typically draw higher current than straight watts because of shaded pole fan motor induction. That could easily push the bill to a few hundred KVAR.

Why ask when all one has to do is look at the watts of the unit, mutiply by hours running in billing period and one would know? -- JHF

The, " issue " is that without empirical data to support a hypothesis on any measurement of expectations is valueless.

This would be like setting a cup of water on a table the night before a summer day and not knowing when the sun will rise or set, the average temperature or humidity or any other pertinent information and making an accurate or partially accurate claim as to how much water will evaporate from the cup. The only part of the test that you would know is that it is a summer day.

The basis of the question has absolutely nothing to do with a humidifier.

The question attempts to make a comparison with the amount of kilowatts and or costs thereof.

The insertion of a humidifier is a diversion. There is no mention in the question that a humidifier was used in the previous house.

The cost of electricity used at the old house compared to the electricity usage at the new house cannot be established until a baseline value is established, then a hypothesis can be constructed.

Jp, ha ha! Gotta love them funnies.

From the OP:

"The old owner confirms their bills were less as well."

This establishes, for the purpose of this exercise, the baseline. The previous bills were less as well. There is a reasonable implication the kWh consumption increased with the addition of the appliance.

That's what I'm seeing as a comparison, a typical residential refrigerator uses about half of the current of a dehumidifier in overall operation.

Does all this have something to do with the latent heat of the water, or maybe the gas to liquid phase change? Offhand I would guess yes, but would also guess the impact is quite small.

What are we missing?

All of this is a guess. Get facts. Then one can draw conclusions. Amp meter incoming lines to main panel. Start turning things off and on and see what draws how much current. Then you know. Even if you have wierd stuff going on. (Contactor stuck on A/c while in heating mode., heating and cooling at the same time.) You would know how much the de-humidifier is drawing and every thing else that is taking power. Of course, as has been mentioned, was this a one month bill or was the first billing cycle messed up so it was a month and a half. Lot of thing can be done on site that this forum can only speculate about. - JHF

I am a fan of a device called a Kill-A-Watt. It plugs into an outlet and your device plugs into it. It monitors volts, amps, watts, VAR, watt-hours, VAR-hours and power factor. I use it currently on some business related equipment specifically to keep track of KW-H for business related tax deduction purposes. It works well for tracking down power usage. The device is cheap and easy to use.

A refrigerator runs only part time. A dehumidifier in a water rich environment runs continuously.

No, it (dehumidifier) has to power down occasionally, deice the cooler.

As I recall, mine ran (estimated) 25% - 33% on. Emptied the water capture bucket twice a day. This makes the numbers even more mystifying.

Did yours have a defrost cycle?

Yep - if I selected setpoint at 20% RH (or whatever the lowest setting is) device would run until it froze up, then stop and deice the plates, then start back up again when the thaw was complete. I would guess this was more like 90%-95% on.

"a typical residential refrigerator uses about half of the current of a dehumidifier in overall operation."

Actually, that makes sense, at least under certain conditions. A refrigerator only has to cool the air, and consequentially remove some water from it (temporarily, since that water is normally evaporated back into the ambient air). A dehumidifier has to cool the air below the dew point to condense the water, but apparently then heats the dried air back up again to avoid cooling the ambient temperature.

I've never had, nor operated, a dehumidifier; in fact, I've always avoided humid climates when possible, so I'm NOT speaking from experience. The only places I remember wishing I had a dehumidifier were close to or in the tropics (principally Puerto Rico and Hawaii), and in those places I would definitely turn off (or disconnect, if necessary) any heater. I doubt if a defroster would be required in such places.

Let's elaborate on Relativity PL's post 10. December in the Midwest USA, furnace turns on to heat house (-3 F outside temperature). The thermostat reads low humidity in upper level living area, triggering an Aprilaire unit to add moisture into dwelling (ahh, 69 now feels like 72 and no more static shocks from the spouse). Basements are typically the lower level and become cooler and more humid due to less dense warm (less dense dryer too) air rising. The cooler humid air trapped in the basement becomes more condensed and hangs around creating a damp musty stale air smell. Dwellers purchase dehumidifier and place it between a floor drain and open pit sump (not good to place unit near unlimited open water sources). They program it to 30%RH (I want this dank smell gone ASAP). Every 4 hours it beeps and somebody heads downstairs to pour the full tray down the floor drain (refer to open water source above). Each day gains a little time between bucket dumps and it doesn't smell so bad anymore, but there is a serious static issue on the upper level again. Boil a kettle of water every day... Weeks later, dump timing set at 8 hours consistently (new alarm clock?), but what is that discoloration in the concrete floor in front versus behind that dehumidifier? We have sucked the moisture out of everything... better adjust the RH% setting.

IMHO: Basically you are running 3 separate (inefficient) systems that continue to fight with each other and run almost constantly. A better option may have been to simply improve the air exchange between lower and upper levels. When experiencing shock therapy in the upper living area and dank gym socks or under-roos in the basement laundry area, it is time to open up that basement and exchange that air. For forced air systems, open up air returns at the basement level and restrict some of the air returns from the upper level. Run the fan in the on position for several hours to equalize both levels. A couple days during the week turn the fan to "on" when getting home from work and switch it back to "auto" before bed to sustain the better exchange.

Humid air is LIGHTER than dry air at the same temperature and pressure. The molecular weight of water is 18 (O=16, H=1, H₂O=18); the average molecular weight of dry air is ≈29 (N₂=2*14=28, O₂=2*16=32, 80%*28+20%*32=28.8). Small amounts of other gasses, such as CO₂ (mol wt=44) raise it slightly. In order to maintain the same pressure, every water molecule added to a given volume of air pushes some other (usually heavier) molecule out of that volume.

Also, an open drain should be just that: a drain, not a source of water. Obviously there will indeed be a small amount of evaporation from that cool standing water in the bottom of the pipe, and more for a little while after you dump the bucket down the drain. but that evaporated water will be tiny compared to the amount of water produced by one person breathing, and in many basements, compared to the amount of water coming in through the floor and walls.

You do have a very good point about adding water in one part of the house and removing it from another.

The easy thing to do is turn it off. Then check running costs for the same period.

It is not all bad though - it is counter-intuitive - but a compression fridge has an an efficiency of over 100%. For the power it consumes it returns air to the room at a higher temperature than would an ordinary heater of the same power consumption for the same air flow.

The expert physicists here know the maths better than I do.

I see your point, at least during heating season. It's definitely NOT true during the cooling season.

Thanks for all the responses -- I posted the answer in the OP.

What?

Boy, this one is a Shaggy Dog story.

Perhaps a review of Chekov's Gun is in order.

Tony was correct in #29: "The basis of the question has absolutely nothing to do with a humidifier." I'm throwng him a GA for that. In fact, I'm going thru the thread and pass out a GA to anyone that questioned the challenge. Sheesh!