Wasting@Home - Confessionals

[mopo3]

well when they start selling electricity in BTUs let me know and I'll change my calcs, but until then my energy balance holds true, just change the numbers to match your situation. I am not going to do this mod to my apartment, because it isn't mind to make changes on, so the numbers mean nothing to me, but having a chemical engineering background I thought I would help others by setting up the equations for them so they could see the possible benefits. I'll remember to keep it to myself next time.

[WTFM8]

Originally Posted by mopo3

I'll remember to keep it to myself next time.

Yeah, quit trying to tell me how to use less energy. That's not the point of this site at all!

Ass.

[Arminius]

Originally Posted by Who

Leaving the hot water running albeit slowly while shaving. No excuse. Anyone else letting water get heated for nothing or worse?

4,500 sq ft house, part of which (1,300 sq ft) is a true mother-in-law suite.
5 bedrooms
2 kitchens
3 full baths and 2 half baths
2 furnaces and 4 heating zones
150 lights, half of which are compact flourescent
Attached garage - 3.5 car garage

Highest utility bill was two months ago: $575 gas + electric

[Who]

mopo, no my fault. Sorry, I was just trying to give something that might be easier to remember. ΔT calcs are easy and 8.3 pounds per gallon.

There are 3413 BTUs in a kilowatt if you want to convert your bill. It's just some of us don't know what mols are, but non-electric water waters, furnaces, and boilers all have BTU ratings. The Eurpopean alternative is kilowatts. I have a 32 KW boiler, although they are sized by BTUS here.

I wasn't at all trying to dismiss what you are saying. I did want to point out that some research that's been done (NRC) has showed transfer efficiency to be in the 30 to 60% range for factors like length, loop wrapped piping diameter, drain diameter and even manufacturer. I'll add the link if I could find it.

I have no intentions of offending you, just wanted to show what maybe easier to remember calculations. I tend to think in BTUs.

What fields use mol as a measure and what does it represent?

http://www.regie-energie.qc.ca/audie...2_28sept07.pdf

[roflwaffle]

Originally Posted by WTFM8

Yeah, sucks very little fuel! Viva la 1980s Hondas!

Shoot, yer porkin' yers out! Those little things should do 60+mpg easy peasy.

[WTFM8]

Father MPG, it's been 4 tanks since my last confession. Yesterday, father, I cranked up an industrial shrink wrapper at my workplace to wrap a single small box. This probably wasted as must electricity in 10 minutes as I use in my home in a day. Furthermore, I sometimes wash my car with hot water... I know it's shameful. And, from time to time, I leave my TV on the weather station while I'm using my computer just because having the Doppler maps in the corner of my eye comforts me. Also, I sometimes turn on my juice-sucking space heater just so my dogs can be warm while they sleep. And most offensive at all, I take 10 minute showers each morning... for shame...

[WTFM8]

Originally Posted by roflwaffle

Shoot, yer porkin' yers out! Those little things should do 60+mpg easy peasy.

I'm working on it! Damned commute is kryptonite for MPGs! Someday she'll pull 60...

[Who]

WTFMB, so would pulse and glide entail 16 minute showers every other day?

[mopo3]

mols are used by scientist and engineers, maybe others too(a mol is 6.02x10^23 atoms or molecules). I did the conversions in plain sight as best I could and I later posted a link to an excel sheet that will do the calculations for you (I left it as an .xls file so you could open it with either microsoft office or open office). If you work with a lot of equations with differing units trust me it sometimes is easier to just convert to the metrics, though it could be done in made-up units if you knew the conversions.

I also stated my assumed 100% heat transfer which to get close to would require quite a large heat exchanger (I work at an oil refinery, we have a lot of these that are bigger than mack trucks). I also assumed that the flow in is the same as out but since the water in the shower is hot and cold mixed to get a comfortable temp then you would have more later on the hot side than cold going to the water heater. (i.e. I neglected the mass term to simplify the equation).

8.3 pounds of water per gallon x 2½ GPM max x 60° x 60 minutes = 75 MBH

MBH = thousand BTUs per Hour?

Does this include waters heat capacity? that is the Cp. I don't know what that is in standard units, but I could have converted it from metric.

I don't mean to lose it, but it is hard to read something and get how someone is saying it sometimes, I'm not so good at that. I think simple calcs are great and I use them all the time, but this website is very much about hard numbers when possible

[Who]

Originally Posted by mopo3

MBH = thousand BTUs per Hour?

Exactly

It does not include the water heater's capacity. It's just looking at the usage. Most gas water heaters consume around 40 MBH and their output is less so they wouldn't be able to sustain a 2.5 gallon shower. Electric waters typically have 3KW, 3.8KW or 4.5KW elements. Since for the vast majority of them only one element is on at a time, the recovery is only 10 - 15 MBH. We shower until we are clean or the water gets cold... unless you are my kids and then you shower until the water gets shut off from the basement by the BTU keeper.

BTUs make for hard numbers. A BTU is the energy needed to raise one pound of water 1 degree Fahrenheit. The pounds per gallon varies with temperature of course but not enough to factor here. They are accurate units but sinfully outdated. North American home energy metrics are like aviation in that they are slow to switch over to metric, even when you live in a metric country.

Thanks for the explanation of mols.