# Acceptable CCF usage for gas water heater?



## ls3c6 (Jul 6, 2009)

It's a 2001 AO Smith unit 40 gallon, I run it at an indicated "130f" which produces about 118-120f at the faucets, I take one shower per day and the unit consumes about .45ccf/day with an ambient temp of 60-70f, seem right?

I've removed the burner to clean it and flushed the tank.


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## Grampa Bud (Apr 6, 2009)

At a 1/2 P.S.I. you have more air in your lungs than the heater has gas. Make a box out of cardboard 1'x1'x1' (a cubic foot) then cut it in a little more than half. The smaller volume half is what your heater has consummed (all day??? or per hour when firing???) You may only take one shower per day and you may be the only person in your dwelling, but you have a lot of temperture drop from the tank to the fixtures 130F down to 120F. Newer heaters in a well insulated home usually run 2-3 degrees variance. This cooling of the heater causes it to run more often to maintain your 130F setting. Try wrapping the heater in a thermal blanket if you're
concerned about gas usage and/or are looking for higher efficiency.


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## ls3c6 (Jul 6, 2009)

Grampa Bud said:


> At a 1/2 P.S.I. you have more air in your lungs than the heater has gas. Make a box out of cardboard 1'x1'x1' (a cubic foot) then cut it in a little more than half. The smaller volume half is what your heater has consummed (all day??? or per hour when firing???) You may only take one shower per day and you may be the only person in your dwelling, but you have a lot of temperture drop from the tank to the fixtures 130F down to 120F. Newer heaters in a well insulated home usually run 2-3 degrees variance. This cooling of the heater causes it to run more often to maintain your 130F setting. Try wrapping the heater in a thermal blanket if you're
> concerned about gas usage and/or are looking for higher efficiency.


but is it worth my time buying a brand new unit vs. the 2001 one I have installed (it has R-07 insulation in it already, but no blanket) or would an aftermarket blanket make any difference?

I'm trying to decide if it's remotely worth replacing since I could do it myself and it's 8yrs old anyway *shrug*


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## Grampa Bud (Apr 6, 2009)

It's worth keeping. The new tanks are 300-500 dollars just for the unit and while you may be able to do it yourself the unit you have right now appears to be working very nicely. Just get a heater thermal blanket (maybe 50 bucks) and some pipe insulation for your sizes of pipe for the HOT side from the tank to as near your fixtures as you can get. The best rule of thumb with water heaters is if they don't leak and don't cause you the national debt in energy costs is DON'T TOUCH IT. Water heaters can leak right out of the box or they can last 30, 40, 50 years with no problem. My first one lasted 29 years and the only reason I took it out was my family was growing and I needed more draw down at the same pressure and temperature. The one I have now is 10 years old going on 100.


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## ls3c6 (Jul 6, 2009)

Grampa Bud said:


> It's worth keeping. The new tanks are 300-500 dollars just for the unit and while you may be able to do it yourself the unit you have right now appears to be working very nicely. Just get a heater thermal blanket (maybe 50 bucks) and some pipe insulation for your sizes of pipe for the HOT side from the tank to as near your fixtures as you can get. The best rule of thumb with water heaters is if they don't leak and don't cause you the national debt in energy costs is DON'T TOUCH IT. Water heaters can leak right out of the box or they can last 30, 40, 50 years with no problem. My first one lasted 29 years and the only reason I took it out was my family was growing and I needed more draw down at the same pressure and temperature. The one I have now is 10 years old going on 100.


gotcha, the hotside is insulated throughout the house but i've always suspected the thermostat wasn't "accurate", any way to clean/verify tstat operation?


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## Grampa Bud (Apr 6, 2009)

Nope not for you and I. Just the manufacturer


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## ls3c6 (Jul 6, 2009)

well each "setting" seems to be about 10f shy of the actual temp

i'm set to "A"/130f but I get 120

I like HOT showers, but I dont' want to turn it up any further and run the gas bill up, i'd probably prefer "B" / 140f though...

Also I noticed when it's set to "A" I have to turn it to "C"/150f or past to make it start up


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## Yoyizit (Jul 11, 2008)

ls3c6 said:


> I take one shower per day and the unit consumes about .45ccf/day with an ambient temp of 60-70f, seem right?


We use 35 therms/month for two of us to heat the water. Normal water usage is 100 gals. per person per day, with probably 2/3 rds of this being cold water.
1 Therm of energy can be had from approx. 100 cubic feet of natural gas.
The heater may run 5 min out of 7 hrs to make up for insulation loss.


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## ls3c6 (Jul 6, 2009)

Yoyizit said:


> We use 35 therms/month for two of us to heat the water. Normal water usage is 100 gals. per person per day, with probably 2/3 rds of this being cold water.
> 1 Therm of energy can be had from approx. 100 cubic feet of natural gas.
> The heater may run 5 min out of 7 hrs to make up for insulation loss.


sounds about right then, i take 15-20 minute showers (shave in there and everything and i'm lazy so i stand there awhile), i avg ~15ccf a month with the water heater, 1 load of laundry in the gas drier a week here in the summer, but in the winter running the furance 65f ~8hrs a day and ~60 offpeak I used up to 90ccf a month, 2000sq/ft 2001 built bilevel, 9" of insulation in the attic, 80% efficient furnace


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## Yoyizit (Jul 11, 2008)

Would you repeat that? :laughing:

I don't know the 95th percentile for resi. water usage; it's probably high, brought up by those with automatic sprinklers.


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