Reduce water heater usage? 1yr old 40k BTU 40gal Bradford White

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Old 11-29-10, 01:37 PM
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Reduce water heater usage? 1yr old 40k BTU 40gal Bradford White

It is not a power vent unit, have it set @ 120f, it's in the furnace room which is in the finished basement and in the center of the foundation.

I shower once daily and don't use much hot water, it still consumes .5ccf/day which trans to about 3 minutes per hour over 24hrs, would adding a blanket help at all or is this about as good as it's going to get with a unit like this?
 
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Old 11-29-10, 05:15 PM
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15 ccfs/month is pretty minimal consumption for a water heater.

There are ways to cut that. For example, you can turn the gas control to the water heater to "pilot" which prevents the burner from turning on but keeps the pilot lit.

You can experiment with leaving the water heater in that position. The pilot light typically will keep the water warm ---- you might be able to leave it set in that position for several days before you are motivated to let the tank PARTIALLY heat up.

The idea is to minimize the heat loss from a big tank of hot water sitting there 24/7.

This can actually be an entertaining game you can play that will save you a few bucks.


To be a real winner, shut the hot water heater off and just heat two quarts of hot water for a daily sponge bath. You don't need floods of hot water to stay squeaky clean. Two quarts of hot water, a towel and soap is all you need, but it does take some practice and skill!

This is best look at as a hobby that will save you a few dollars.

(Next ask me about using rain barrels instead of city water!)
 
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Old 11-30-10, 05:26 AM
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I shower once daily and don't use much hot water, it still consumes .5ccf/day
Perhaps Iím missing something, but your 15 ccf/month gas consumption seems like an exceptionally high amount if that is just for a water heater and only 1 person using little hot water. You donít state whether youíre using natural gas or LNG (i.e., propane) but Iím assuming natural gas (if using LNG, your gas usage would look ridiculously high).

My understanding is that natural gas contains about 1,000 btu per cubic foot and propane contains a net of about 2,316 btu per cubic foot. This gives a ratio of about 2-1/3 btuís per cubic ft. If your 15 ccf/month is converted to propane, you would be using about 6.5 ccf/month.

While Iím a low user of energy and have high energy efficient appliances, my usage of propane gas is averaging 2.45 ccf/month for YTD 2010. This is for a water heater, dryer, and stove. I realize you live up north, and the cold water intake to your tank would be at tempís far lower than what would occur in S. FL. I read SeattlePioneer saying that 15 ccf/month is minimal gas usage, and he too lives up north in a very cold climate. Iím just surprised that a cold climate makes such a dramatic difference although Iím assuming your water heater is located in a heated room. Perhaps Iím making a mistake in my conversion assumption or math. However, if reasonably correct, your gas usage just for a water heater using little hot water looks very high to me (based on someone living in a warmer climate).
 
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Old 11-30-10, 07:13 AM
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Just to clarify....LNG is not the same as propane. I really doubt anyone would have a LNG tank in their yard...lol.
 
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Old 11-30-10, 09:57 AM
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Gunguy is correct. LNG is the acronym for Liquefied Natural Gas and no consumer uses LNG. The acronym for propane and butane is LPG for Liquefied Petroleum Gas.
I read SeattlePioneer saying that 15 ccf/month is minimal gas usage, and he too lives up north in a very cold climate.
I have to laugh at that statement, Seattle is NOT a "very cold climate". The temperature in the greater Seattle area rarely drop to zero and many winters it doesn't even drop below freezing. I live ab out ten miles northeast of Seattle and while we had a cold snap last week the low temperature at my house was 15 degrees, hardly what I would call "very cold" when compared to even eastern Washington state.

In our area water heaters are often installed in unheated garages and that could explain a slight increase in gas consumption during colder weather. The whole truth is that natural draft gas-fired tank-type water heaters are a fairly abysmal method of producing domestic hot water and especially so when the amount of hot water consumption is low and at infrequent intervals. Water heater blankets can, iin some instances slightly decrease the "standby losses" of a tank-type water heater but it is the central flue always having a draft of room-temperature air flowing through that is the biggest loss. The constantly burning pilot light is also a significant loss when the water is used infrequently.

In cases of fairly infrequent usage the instantaneous (tankless) water heater really shines when compared to the standard gas-fired tank. The installed cost is quite high, probably three or four times the cost of a standard heater and in many installations there will be additional maintenance required over that of a standard tank. But if you are the type who ignores capital costs and wants the lowest operational costs then the instantaneous is what you want.
 
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Old 11-30-10, 08:55 PM
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I can hear the draft of the outdoor air through the piping, probably no way to eliminate that though eh?

Yes i'm on natural gas and this 1yr old standard unit is consuming less than the one it replaced which never cycled properly anyway and didn't keep the water warm enough 75% of the time
 
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Old 11-30-10, 09:49 PM
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A standard water heater is gravity vented and has a "draft diverter" on top of the water heater that forms a gap between the vent and the water heater. This allows room air to be sucked up the vent 24/7. If the water heater is located in a heated area, that means heated room air being sucked up the vent, and every cubic foot of heated room air going up the vent is replaced by a cubic foot of cold air from outdoors infiltrating the dwelling.

That's a significant source of inefficiency in gravity vented gas appliances.

Another source of inefficiency is that the heated combustion gasses are directed through the flue in the middle of the storage tank. When the burner is off, that metal flue is kept nice and warm by the hot water, and air flows by convection from the burner compartment up through the flue and then up the vent and outdoors. Again, every cubic foot of heated room air going up the flue is replaced by a cubic foot of cold air from outdoors.


The main reason for higher gas consumption to heat water during the winter is that water coming into the tank is usually a lot colder during the winter than during the summer. Water from a city water supply may heat up to sixty degrees or more during the summer and get down to 35-40 degrees during the winter.

It can take 50% more energy to heat that cold water compared to the warm water during the summer.

Your water utility can give you the typical water temperatures during various months if you ask them.



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Old 12-01-10, 05:26 AM
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The main reason for higher gas consumption to heat water during the winter is that water coming into the tank is usually a lot colder during the winter than during the summer. Water from a city water supply may heat up to sixty degrees or more during the summer and get down to 35-40 degrees during the winter.

It can take 50% more energy to heat that cold water compared to the warm water during the summer.
Seattle Pioneer-Thank you for answering my question, and the info on cold water intake is helpful .

My point was that the cold water intake here in S. FL relative to Seattle, WA or Grand Rapids, MI would be quite different. A search shows our average range of temps as 55į-75į during January (coolest) and 74į-90į during July (warmest). Perhaps I should have referred to Seattle, WA as having a semi-cold rather than very cold climate. Someone living in Prospect Creek Camp, Alaska or Stanley, Idaho could nit pick the notion that eastern Washington state might be a very cold climate.

I donít recall taking a temperature reading on the cold water side of faucets in my home. At my irrigation pump station that is drawing water from a lake, the water temp during summer months is in the mid-80ís but can go higher during the hottest months when air temps are approaching 100į. When showering, very little hot water is used as the water from the cold water side is mostly adequate during our hottest months. When temps drop during the winter months, the water being drawn from lake is around 60į but fluctuates when cold snaps roll through.

While these are guesstimates, Iím still trying to rationalize why I see no measurable difference in my gas usage between summer and winter months assuming a 25į temperature differential in the cold water intake. This may be attributable to different usage patterns which mask the effects of increased gas usage at the water heater. In trying to make an apple to apple comparison, I attempted to adjust for btu content between natural gas and LPG although not sure Iím adjusting that correctly given possible differences in the way a water heater burns these two different fuels.

It seems to me that OP could gain insights into improving energy efficiency by comparing gas usage during winter vs. summer months. If OP finds that his gas usage appreciably spikes during the winter months, that may lead him to adopt a certain set of energy saving options to address the cause of that spike if waste energy is involved (e.g., insulating blanket or jacket, pipe insulation, point-of-use tankless water heater for showering, etc.). I would think energy efficiency gains from pipe insulation may be highly dependent on differential temps of ground vs. air temps, and how much pipe is exposed to colder air temps. On the other hand, if his gas usage is fairly constant across all months of the year (similar to mine), then there may be a different set of energy saving options to address. For the latter, it usually requires more attention to the estimated economic cost vs. benefit tradeoffs if the energy saving option(s) are expected to have minimal effect.
 
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Old 12-01-10, 07:26 AM
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Consumption summer to winter are pretty similar, on the most ideal month I might squeeze through with .3ccf/day, or .5 average/worst.
 
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Old 12-01-10, 08:56 AM
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I have a water heater installation similiar to the OP, a 40 gallon natural gas fired unit sitting in a utility closet in the middle of a heated and finished basement. I'm single and take one shower a day, wash two loads of clothes a week in a top-loading washer, and run the dishwasher once a week. In the summer, the water heater is the only gas-consuming appliance. I typically use around 0.5-0.6 MCF of gas each month during the summer. I have to read my own gas meter, so I keep pretty good records on consumption. By my calculations, this usage comes to 16.6 cu ft/day of natural gas, or.166 ccf. My municipal water is well water, which is fairly cold in the summer, and I keep the heater at the 120 degree mark.

Adding an insulation blanket to your water heater wouldn't save anything, as any heat lost by it to the surroundings is utilized in keeping your finished basement area warm. In my case, at least, in the summer, the basement tends to be too cool, so the little added heat thrown off by the water heater is welcome.
 
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Old 12-01-10, 09:29 AM
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Originally Posted by Beachboy View Post
I have a water heater installation similiar to the OP, a 40 gallon natural gas fired unit sitting in a utility closet in the middle of a heated and finished basement. I'm single and take one shower a day, wash two loads of clothes a week in a top-loading washer, and run the dishwasher once a week. In the summer, the water heater is the only gas-consuming appliance. I typically use around 0.5-0.6 MCF of gas each month during the summer. I have to read my own gas meter, so I keep pretty good records on consumption. By my calculations, this usage comes to 16.6 cu ft/day of natural gas, or.166 ccf. My municipal water is well water, which is fairly cold in the summer, and I keep the heater at the 120 degree mark.

Adding an insulation blanket to your water heater wouldn't save anything, as any heat lost by it to the surroundings is utilized in keeping your finished basement area warm. In my case, at least, in the summer, the basement tends to be too cool, so the little added heat thrown off by the water heater is welcome.
I guess it's to be expected then, ~$15/mo isn't too bad, just seems as if you don't use much you're paying anyway
 
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Old 12-02-10, 06:48 AM
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The cost of natural gas used is only one component of the typical gas bill. You also pay a charge for transportation of that gas, and a fixed charge to provide gas service to your house, regardless of use. Then there are the taxes! I find it frustrating that even though I only use a half MCF a month in the summer, the charge is similar to yours....around $25. Almost all that charge is for the fixed costs of providing service and reading the meter.
 
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