Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

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Deaconfan
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Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Deaconfan » Thu Mar 29, 2018 10:33 am

March 2018
BIlling days: 28
Avg Daily Temp: 37 F
Therms used: 221.1
Avg Therms/Day: 7.9

March 2017
Billing days: 29
Avg Daily Temp: 38 F
Therms used: 174.6
Avg Therms/Day: 6.0

GIven that the temp. basically stayed the same year over year, any ideas why the therms used would have gone up almost 33% per day in 2018? I haven't been keeping the house any warmer than usual (70 degrees). Furnace is only 3 years old and is checked twice a year (filters replaced, etc.) Do I maybe need to have my ducts cleaned out? Any other suggestions?

Thanks, Deaconfan

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CAsage
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by CAsage » Thu Mar 29, 2018 10:37 am

Definitely not duct cleaning - I've always thought that was a ripoff, and definitely not for a system that's only three years old. Who is in charge of the thermostat? Any change in windows left open, people home more during the day, more hot water or cooking (as in, what else is gas used for...). I would take a look at several months data before I worried too much.
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Chan_va
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Chan_va » Thu Mar 29, 2018 10:42 am

It could be a case where averages are deceiving, and outliers matter. Have you had a lot more really cold days and really warm days this year? The energy efficiency as the temperature drops is not linear.

Amphian
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Amphian » Thu Mar 29, 2018 10:44 am

What else does the gas run other than heat? Hot water? Dryer? Stove? Any reason those might have run more than normal?

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lthenderson
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by lthenderson » Thu Mar 29, 2018 10:44 am

I also wouldn't look to much into over one month's billing especially if the previous months had them closer together for similar temperatures.

mortfree
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by mortfree » Thu Mar 29, 2018 10:47 am

how old is your thermostat?

And if you're interested in tracking usage, I would recommend a Nest thermostat or similar so you can see the hours per day (and when) the furnace was running.

oldfatguy
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by oldfatguy » Thu Mar 29, 2018 10:49 am

Chan_va wrote:
Thu Mar 29, 2018 10:42 am
It could be a case where averages are deceiving, and outliers matter. Have you had a lot more really cold days and really warm days this year? The energy efficiency as the temperature drops is not linear.
This is the most likely explanation, IMO.

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eye.surgeon
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by eye.surgeon » Thu Mar 29, 2018 11:00 am

Any visitors/guests that month? An extra hot shower per day will noticeably raise your gas bill. Were you out of town for part of this month last year? Same thing.
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David Jay
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by David Jay » Thu Mar 29, 2018 11:03 am

I would compare at least 3 months bills (a month either side) together. The meter may not be read on the same day and the billing cycle may move up to a week from year to year - note that they are billing for 28 days in a 31 day month.
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Grt2bOutdoors » Thu Mar 29, 2018 11:06 am

Average temperatures are skewed by outliers. On a spell where the temperature is 28 degrees for two-three days straight, you can bet your furnace is working more often than on a day where the temperature rose to 45 stayed there for a week before normalizing back down to 36-37. Don't rely on averages to tell the story.
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neilpilot
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by neilpilot » Thu Mar 29, 2018 11:21 am

In addition to many of the possible causes mentioned above, consider the average wind velocity during the March 2017 and 2018 billing cycles. If the average wind velocity in 2018 was measurably higher than 2017, and especially if your residence suffers from wind infiltration, than you could consume measurably more energy to heat your home during an otherwise equivalent degree-day period. To a lesser extend wind direction can also influence home heat loss, although velocity is the most significant variable.

Of course I'm also assuming that the bills are based on actual measurements, and not estimates.

Trapper
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Trapper » Thu Mar 29, 2018 11:24 am

Could be a misread meter

zkzkzk
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by zkzkzk » Thu Mar 29, 2018 11:31 am

Is it an actual or an estimated reading? I received a high use gas bill for January, it was an estimated bill and corrected itself in February when they actually came out and read the meter.

chambers136
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by chambers136 » Thu Mar 29, 2018 11:36 am

Try to find the ‘heating degree day’ data (HDD) for the time periods in question. Then compare them he two. You can often find the data online for you zip code or even for a weather station near you.

mrc
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by mrc » Thu Mar 29, 2018 11:51 am

Around these parts, March has been colder than Jan or Feb. The 28-day averages are notoriously noisy.

Were the meter readings actual or estimated?

After I installed solar, I found electric meter was read only every other month. In the early days, the estimated readings were wildly off.

Can you go back and look across multiple billing cycles (e.g., find usage for other months with similar average daily temps, especially in the fall)? I think it's noise.
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iamlucky13
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by iamlucky13 » Thu Mar 29, 2018 1:40 pm

Chan_va wrote:
Thu Mar 29, 2018 10:42 am
It could be a case where averages are deceiving, and outliers matter. Have you had a lot more really cold days and really warm days this year? The energy efficiency as the temperature drops is not linear.
With gas heat, it will be fairly close to linear, while heat pumps are really significantly affected by colder temperatures. Also, I'd hope the utility is reporting the weighted average based on HDD, not simply averaging the daily highs and lows for the month.

But this is similar to some of the ideas I had. Windy weather cools the house more than calm weather at the same temperature, as do clear nights compared to cloudy nights.

Other ideas:

- Leakage, such as a window, attic hatch, or other space left open
- Faucet left dripping unnoticed on warm or hot
- Family members adjusting the thermostat upward
- Vacation last year with the heat left turned down
- "Upgraded" from a programmable to a "smart" thermostat like Nest. While the idea behind Nest is interesting, it doesn't really know your schedule better than you do, and it can even lead to unnoticed behavior creep.
- Utility company read the meter wrong. I've had this happen to me, but I checked the number on my bill against the meter, realized the mistake, and sure enough, I had a much lower than usual bill the following month.

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munemaker
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by munemaker » Thu Mar 29, 2018 1:43 pm

I had something similar to this happen one time. I never did get to the bottom of it.

FraggleRock
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Not a Mystery

Post by FraggleRock » Thu Mar 29, 2018 1:45 pm

The average temperature is the same.
But, which one is most likely to have higher gas usage?

Image
vs
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madbrain
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by madbrain » Thu Mar 29, 2018 1:47 pm

Do you have any other gas appliances, like clothes dryer, cooking appliances, etc ? If so, this could partially explain the difference too.

Mudpuppy
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Mudpuppy » Thu Mar 29, 2018 2:17 pm

Chan_va wrote:
Thu Mar 29, 2018 10:42 am
It could be a case where averages are deceiving, and outliers matter. Have you had a lot more really cold days and really warm days this year? The energy efficiency as the temperature drops is not linear.
This was going to be my suggestion as well. You could have a month where one week was at 20F, one week was at 30F, one week was at 40F, and one week was at 50F and the average would be 35F. But that would be a vastly higher amount of heating needed for the week that was at 20F than you would recover from the lack of heating needed in the week that was at 50F. So you could easily end up using more gas in a month like that than in a month where two weeks were 30F and two weeks were 40F, and the average was also 35F.

Edit: Typo

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FreeAtLast
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by FreeAtLast » Thu Mar 29, 2018 2:48 pm

zkzkzk wrote:
Thu Mar 29, 2018 11:31 am
Is it an actual or an estimated reading? I received a high use gas bill for January, it was an estimated bill and corrected itself in February when they actually came out and read the meter.
This sort of thing just happened to me. They didn't read my meter for NINE MONTHS, so all I had during that time were estimated readings.....and then made up for the deficiency in one bill! The lady at the energy company could give me no explanation for the lack of actual readings. :oops:
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TSR
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by TSR » Thu Mar 29, 2018 3:13 pm

I once had an unusually high bill and went out to look at the meter. Some shrubbery on the side of the house had grown over the meter. I'd bet that the meter reader guy got frustrated and either estimated it or just gave me a really high number. I have taken no action to correct it, other than cutting back the shrubs.

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jharkin
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by jharkin » Thu Mar 29, 2018 3:21 pm

The proper way to normalize usage for temperature is to divide gas consumption by heating degree days for the month.

Plug your zip code into this tool and it will spit out the degree days for any time period. http://www.degreedays.net/

I picked a station near me and it shows that Mar 1-28, 2018 actually had less total degree days of heating (862 HDD) vs Mar 1-28, 2017 (956 HDD) even though the average was a bit colder.

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Pajamas
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Pajamas » Thu Mar 29, 2018 3:43 pm

The one time this happened to me it turned out to be that they there was a problem with the meter reading. They actually wanted to charge me to come re-read the meter so I waited another billing cycle and it averaged out.

The other strong possibility is the problem with going by average temperature as noted above.

Another possibility is that you were out of town or had guests if your water heater is also gas. My electricity bill drops significantly when I am gone for a week or more and it is just lights and appliances, no heating or hot water and rarely air conditioning. If you had guests you may have used a lot more hot water.

If it is none of those, you might want to check to see if your heating system needs maintenance or replacement. Something as simple as a filter that really needs to be changed can affect the efficiency.

It also occurs to me that you might have left a window open in an unused area upstairs or in the basement or similar.

Deaconfan
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by Deaconfan » Thu Mar 29, 2018 5:40 pm

OP here. Thanks everyone for your replies.

Regarding questions some of you raised:

Our thermostat is three years old.
No windows were left open.
We didn't travel this year or last during the months in question, so the house wasn't dormant for a week or anything like that.

The consensus seems to be that one month does not a trend make, and also that any errors or poor estimates made by the gas company in terms of reading the meter will get ironed out over time. So I'm going to proceed as if this month's bill is an outlier and will carefully monitor future gas bills.

Thanks to all, Deaconfan

SeekingAPlan
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by SeekingAPlan » Thu Mar 29, 2018 6:18 pm

Since last Sept or Oct I had been having the same problem except that I was supposedly using 3 to 4 times more than the amount of gas I usually use. I was at my wits end as far as what to do because the gas company kept insistingthat nothing was wrong & I was just using more gas. They closed every dispute case I opened. My normal bill range is $50 to $125 per month during the cold season. This year that $50 bill was $185 and the rest went up proportionally even though I turned the temperature down to 60 to 64 on the main level and turned the heat off altogether in the rest of the house. If I turned the water heater any lower it would have been off. I did not use my gas dryer at all.

By coincidence there was a letter in my mailbox from the gas company when I got home today. It says, "During a recent test of your gas meter, we determined that it was recording more energy than you actually used." No kidding! Wish they could have figured that out before I had to spend the whole winter in an uncomfortably cold house. Also hoping this is not an April Fool's letter and that the promised check for an unspecified refund amount really turns up and is in the correct ball park.

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just frank
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Re: Mystery: Gas bill says therms increased 33% year over year but temperature stayed the same. Why?

Post by just frank » Thu Mar 29, 2018 6:58 pm

Forgot to put storm windows down in the Fall?

Teen children starting using a lot more hot water?

Difference in vacation time in the two years?

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