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View Full Version : Gas dryers use electricity too!



craigwatanabe
March 12th, 2008, 04:06 PM
And a lot it seems.

I have a gas dryer to help cut down on my electrical costs. And to cut down on my gas usage I would run my gas dryer for about 90-minutes on Air Fluff only then about 30-minutes on Regular with a full load.

I do this everyday fiive days a week times three loads per day, so we're looking at 270 minutes or 4.5 hours just on Air Fluff. Then you add another 1.5 hours for the actual heated drying and that adds up to 6-hours per day or 120-hours per month.

Just for kicks I decided just how much electricity to drive the motor of my gas dryer uses per hour. I was floored when my watt meter read an astounding 300-watts per hour or 36,000 watts per month. To put that into perspective that's 36Kw/month so at $0.39 per Kwhr (Kilowatt per hour) that equals to $14.04 per month.

Now my propane usage before air fluffing came out to $15.00 per month. With air fluffing it came out to $10.00 per month.

So if I just use the gas dryer on regular for 50-minutes per load I use $5.00 more in propane than with air fluffing per month.

At 50 hours per month times 300 watts per hour that equals to 15Kw or $5.85 in electrical usage vs $14.04.

The cost of increased gas usage vs the cost of electricity saved is a net savings of $8.19 per month when you combine both gas and electrical monthly costs.

Hmmm...that still doesn't explain my spike in electricity from $388.39 to $457.59 (for March 2008) especially since I've been doing this air fluffing for over half a year already and during this last billing cycle I actually unplugged my garage chest freezer the day before the meter reader took my Feb 9th reading.

Taking into account any rate increase, according to my billing statement my Kw/day increased from 34.1Kw/day to 38.5kKw/day or an increase of 4.4Kw per day.
At 300-watts per hour times 6-hours per day (current usage) that equates to only 1.8Kw per day. Now the usage didn't change from the previous month so that 1.8Kw/day is a non-issue, but even if it was, that doesn't account for the other 2.6Kw/day.

I'm thinking HELCO didn't read my meter correctly. I know for a fact that my electrical meter doesn't have an AMR attached so the reading had to be done manually with eyes. My elderly mother who's bedroom window is right next to the meter saw the HELCO meter reader just drive by our driveway (going in thru the main driveway and exiting via the side street driveway) without stopping. There was no way that meter reader could have gotten a reading like that. I know, I used to work for the Gas Company and part of my job was verifying defective meter index dials and handling high bill complaints when a meter reader refutes any misreads on their part.

DNR55
April 1st, 2008, 06:52 AM
And a lot it seems.

Hmmm...that still doesn't explain my spike in electricity from $388.39 to $457.59 (for March 2008) especially since I've been doing this air fluffing for over half a year already and during this last billing cycle I actually unplugged my garage chest freezer the day before the meter reader took my Feb 9th reading.

Taking into account any rate increase, according to my billing statement my Kw/day increased from 34.1Kw/day to 38.5kKw/day or an increase of 4.4Kw per day.
At 300-watts per hour times 6-hours per day (current usage) that equates to only 1.8Kw per day. Now the usage didn't change from the previous month so that 1.8Kw/day is a non-issue, but even if it was, that doesn't account for the other 2.6Kw/day.

I'm thinking HELCO didn't read my meter correctly. .
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I had a spike in my HECO bill when there was an underground leak in a hot water pipe. Even though I have solar, the hot water was draining constantly and the electric heating element kicks in to compensate for the temperature drop. The leak never manifested itself in an obvious manner as it was underground. I complained to the solar company because I thought there was a problem with the solar controller or pump. They came out and properly diagnosed the problem. How is your water bill?

GeckoGeek
April 1st, 2008, 07:14 AM
Just for kicks I decided just how much electricity to drive the motor of my gas dryer uses per hour. I was floored when my watt meter read an astounding 300-watts per hour or 36,000 watts per month.

Just to check, what is the name plate rating on the unit? Does you watt meter properly adjust for power factor or is it just a amp meter?

The correct units are "watts" or "watt-hours" not "watts per hour".

The suggestion to check your hot water pipe is a good one.

craigwatanabe
April 4th, 2008, 10:53 AM
Just to check, what is the name plate rating on the unit? Does you watt meter properly adjust for power factor or is it just a amp meter?

The correct units are "watts" or "watt-hours" not "watts per hour".

The suggestion to check your hot water pipe is a good one.


Either way it translates into watts per hour and the meter I have is called the Kill-A-Watt P3 (http://www.supermediastore.com/kilwateldet1.html?WT.mc_id=adwordsACCKillawatt&utm_source=cpc&utm_medium=campaign&utm_term=Killawatt&utm_campaign=cp_ACC_adwords&gclid=CIzZn8WgwpICFRpOagod3w25aw)

It is a true watt meter and displays usage in amps, voltage and watts. It also displays wattage rates.

In electricity, amperes represents the load of a given circuit. Wattage represents the rate of which amperage is being consumed. Voltage represents the unit that equals the duration of load use or wattage consumed (P) per load requirement (I) translating that P/I = E or when solving for wattage: P = I x E.

Maintaining proper voltage and amperage you can manage your consumption of wattage. Drop either and you get power (wattage) loss because the rate cannot keep up with load requirements.

P = wattage
I = amperage
E = voltage

cezanne
April 5th, 2008, 10:08 AM
Wow good breakdown on the cost analysis. Does HD or Lowes carry a similar meter monitor (translated to mean instant gratification)?

BTW, I went to the link that you provided and the latest review says that the unit seems to be recording useage of ALL items plugged into the circuit, not just that outlet. Maybe that could be inflating your numbers a bit?:confused:

Also, ditto on your checking on the hot water leaking unless of course that's gas too.

GeckoGeek
April 5th, 2008, 06:28 PM
P = I x E

Not completely true. It's P = I x E x PF

Where PF is power factor. If the meter you use doesn't consider power factor, it may be giving an abnormally high reading. If your load is high in harmonics (like some electronics) it may not get an accurate RMS reading.

craigwatanabe
April 7th, 2008, 01:18 AM
Not completely true. It's P = I x E x PF

Where PF is power factor. If the meter you use doesn't consider power factor, it may be giving an abnormally high reading. If your load is high in harmonics (like some electronics) it may not get an accurate RMS reading.

It does give your Kw/hr rating as well as running wattage.

And I checked my supply voltage using a VTVM which can read in RMS as well. My gas dryer has no electronics, just a mechanical timer and a motor (with a start up capacitor so it's pretty damped).

The PF for that kind of electrical appliance should be very close to 1.0 anyway making that factor almost moot.

GeckoGeek
April 8th, 2008, 07:50 AM
The PF for that kind of electrical appliance should be very close to 1.0 anyway making that factor almost moot.

Motors by nature are inductive. So I don't think it's going to be unity, but I'd be surprised if the difference is more then 10% or so.

While not an issue in this case, your VTVM may not read accurately. It's calibrated for sinusoids. You need a meter that says "real RMS" that can give you an RMS reading of non-sinusoids. But you only need to worry about that with electronic loads as they tend to switch on/off during each AC cycle.

Given the size of your electric bill, I think you're still missing the big draw that's driving your bill so high. 300W just isn't that much. It's 3 old fashioned light bulbs.

I'll third the comment to check your water heater. The front building in my complex developed a leaking water pipe in the cement slab. No moist spot. The only clue was an elevated water bill and a sky high electric bill. If your heating element develops a short to ground, it can be running at "low power" (for a water heater) full time. I'd think the safety relief would go off or the over-temp breaker would trip, but maybe that's not how it's working out. Make sure there's no dripping faucets.

craigwatanabe
April 8th, 2008, 11:06 AM
Motors by nature are inductive. So I don't think it's going to be unity, but I'd be surprised if the difference is more then 10% or so.

While not an issue in this case, your VTVM may not read accurately. It's calibrated for sinusoids. You need a meter that says "real RMS" that can give you an RMS reading of non-sinusoids. But you only need to worry about that with electronic loads as they tend to switch on/off during each AC cycle.

Given the size of your electric bill, I think you're still missing the big draw that's driving your bill so high. 300W just isn't that much. It's 3 old fashioned light bulbs.

I'll third the comment to check your water heater. The front building in my complex developed a leaking water pipe in the cement slab. No moist spot. The only clue was an elevated water bill and a sky high electric bill. If your heating element develops a short to ground, it can be running at "low power" (for a water heater) full time. I'd think the safety relief would go off or the over-temp breaker would trip, but maybe that's not how it's working out. Make sure there's no dripping faucets.


A VTVM can read RMS by taking into account the leading and trailing edge of a waveform and the peaks. While in the AF as an avionics tech we used VTVM's for RMS readings to calibrate TFR radar systems so there's accuracy in RMS readings using VTVM's.

A PF rating of 10% is high but is temporary as the load stabilizes that's why a constant PF rating should be closer to a factor of 1% for somewhat accuracy over load use. You can spike to 10% but if you scope that spike you'll see a negative spike on the trailing end that kinda balances that initial load.

And yes I agree 300-watts wouldn't bring my electric bill to the point of a high bill complaint. That's why I told HELCO that I believe the increase was due to a misread.

As for my water heater, I have no leak. Water pressure is maintained throughout the night. I have considered the upper heating element as a possible culprit but I checked that and it's not showing an open or a short but a nominal impedance.

I think HELCO's meter reader estimated my meter reading for that month. They're not supposed to but there's no way HELCO would find out unless my meter was read automatically by their ITRON wand. I don't have an AMR electric meter so he had to read it manually. My elderly mother who sits at the window that's next to the meter saw the meter reader drive by without stopping. He didn't read my meter.

DNR55
April 8th, 2008, 07:26 PM
I think HELCO's meter reader estimated my meter reading for that month. They're not supposed to but there's no way HELCO would find out unless my meter was read automatically by their ITRON wand. I don't have an AMR electric meter so he had to read it manually. My elderly mother who sits at the window that's next to the meter saw the meter reader drive by without stopping. He didn't read my meter.
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Back about 14 yrs ago I was told by HECO that they only read every other month and sort of average it out. So if it is too high one month, then eventually the succeeding bills would compensate. I do not know if they still do that.

craigwatanabe
April 8th, 2008, 07:52 PM
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Back about 14 yrs ago I was told by HECO that they only read every other month and sort of average it out. So if it is too high one month, then eventually the succeeding bills would compensate. I do not know if they still do that.

No they do not. I asked them point blank.

DNR55
April 8th, 2008, 08:44 PM
No they do not. I asked them point blank.
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k den
you got a mystery. By the way, you mentioned water pressure as a leak test? The usual method of leak testing is to turn off all the faucets on the property and look at the water meter to see if it is still moving.

Here are other ideas...
Frig/freezer door seals broken-leaking cold air-causes compressor to run constantly. Check the bottom of the doors. That is where your coca-cola and root beer spills and sticks the rubber to the metal. Then the rubber tears and no more seal anymore.

Naughty neighbor runs extension cord tapping off your power.:eek:

GeckoGeek
April 8th, 2008, 11:21 PM
While in the AF as an avionics tech we used VTVM's for RMS readings to calibrate TFR radar systems so there's accuracy in RMS readings using VTVM's.

Unless the unit has the circuits to do the root-mean-square, it won't be accurate.

Another thing that you can look at is the refrigerator and freezers. Older unit can have water work their way into the insulation - and it no longer insulates as well. Your Kill-a-watt should check out the refrig.

It would be nice to scare up an electric meter to put on the water heater. That will tell you how much is going that way. The way to test the element is to measure from the electrical terminals to the tank. That's what will eat the power.