How to Sell Electric Vehicle/Solar Power?

[Brock]

Yup, I have an alarm on my chest freezer. It starts beeping at 25F. It has a min/max temp as well. I do have it set low, cycling about -5 to +5F and after 10 hours it's typically about 20F to 25F (if it was opened a lot or my wife put something in it to try to freeze it) most likely depending on where it was when it shut off. Ideally I would like a second thermostat to force it on, just in case it hit 25F or so, but it hasn't done that to often so I am not worried. We just hit our "winter" rate hours here. 8a to noon is peak, noon to 4p is off peak, 4p to 9p is peak and 9p to 8a is off peak again. So the longest run I have is 5 hours on the freezer, no problem at all.

And because it is a chest freezer opening it doesn't affect it as much, but it is a pain to get things in and out.

Our fridge is also shut off for the last 2 hours of on peak rates. It warms up rather quickly, and my wife hates that the light doesn't work, but she lives with it.

We are at the point here that gas is about 5% more then off peak electricity, not to mention any losses, even the 92% efficient gas furnace costs 13% more then straight off peak electric.

I am so glad I found you all, now I don't feel quite so nuts.

 

[Brock]

Oh, I just installed a heat recovery ventilator, a Fantech VHR 1404 http://www.fantech.net (I still don't know how to do URL's) Since last week we were in the 40's I finally hooked it up. It is an amazing thing. I was dumping 81F air (from the pool room) in to the box. The box then dumped that air at 62F. Incoming air was 44F and air in to the house was 69F! My only explanation for the extra heat was the humidity in the air. Once the pool room had dried out it was still above 62F!

In the past I had been dumping about 25cfm 24/7 and make up air was just dropped in the furnace. This should make a HUGE difference when it is -10F out this winter. I do wonder about freezing the heat exchanger, time will tell.

 

[BB]

I agree that the cold air dumps when opening the door--but we are talking about 300 lbs of food and 0.8lbs of air (0.08 lbs (35 grams) per cu.ft. of air).

So, even dumping 10 cu.ft. of air (assuming 15 cu.ft. freezer with 5 cu.ft. of food weighs 64 lbs/cu.ft--assuming density/properties similar to water). You would only be dumping, roughly, less than .3% of your heat (mass) with each opening of the door. And much less than 0.3% of your total heat if you include the energy of freezing/melting water itself (which air does not have).

It turns out that placing unfrozen items in the freezer is going to add much more heat--then one should override the 6 hour off cycle.

As a rough guide, it takes about the same amount of energy to freeze 1 gallon of water as it takes to reduce the heat from 212 F (100 C) to 32 F (0 C) (really, 1 UNIT of water in any metric/English standard).

So, technically, placing 1 gallon of water of 70F water would bring how much water from 0F to 31.9F would be found by:

212 (heat to freeze) degree units + 70-32 du (cooling to freezing point) = ~250 units of heat (to lazy to use real btu's etc.)

0F - -31.9F = 31.9 du (heat required to bring 0F food to near thawing)

250/31.9 = 7.89 "thawing factor"...

So, very roughly, placing 1 unit of room temperature food into a freezer would bring to thawing temperature approximately 7 units of deep frozen food...

In the second case, if you are bringing a load of food home from the store and place it in the freezer, you should override the energy conservation switch.

All of this is kind of interesting to me because I thought, like everyone else, that an upright freezer is much less efficient because of the dumping of heat issue... However, when I looked at the energy sticker and saw that there was approximately 20% difference between a chest and upright freezer, it did not seem that there was that much lost to door operations...

Assuming that operating the door, freezing new food, and other consumer operations are included in testing... I looked for the test procedure, but I was not successful...

In any case, there is still not that much heat dumped out with opening the door vs the costs of freezing the food in the first place.

-Bill

 

[Darell]

We are at the point here that gas is about 5% more then off peak electricity, not to mention any losses, even the 92% efficient gas furnace costs 13% more then straight off peak electric.

Wow. I assume this is apples-to-apples price per unit of energy? Yikes. Remember way back when... when gas applicances were WAY cheaper to operate?

I am so glad I found you all, now I don't feel quite so nuts.

Hey - it doesn't make you any LESS nuts. Just drags us down with you.

 

[BB]

Someone a week or so ago posted this energy cost comparisons link, either in this or Darell's other thread. It makes it very easy to compare price at point of use for various home fuels (oil, gas, lp, hardwood, softwood, electricity, and coal).

Our new gas rates per therm (as of October 7th, 2005) are:

$1.57886 (baseline)
$1.79375 (over baseline)

Baseline charges have recently been round $1.10 per therm and a couple of years ago, were even below $0.80 / therm at times.

Assume that my new 10% increase off-peak power will be $0.10 / kWhr and peak will be $0.13 (winter) and $0.32 (summer) (all assuming baseline usage, using the above link with 80% natural gas efficiency):

Electric:
$32.23 per Million BTU of Heat delivered to home ($0.11/kWhr)
$38.09 per Million BTU of Heat delivered to home ($0.13/kWhr)
$93.76 per Million BTU of Heat delivered to home ($0.32/kWhr)
Gas:
$19.75 per Million BTU of Heat delivered to home ($1.58 per therm)

I don't see the numbers crossing yet... I think that Natural Gas will remain cheaper unless:

Either natural gas goes above $2.56 per therm, or electricity drops below $0.07/kWhr in our area... (baseline G-1 and E-7 rates assumed).

-Bill

 

[Brock]

Bill, that is so true about the amount of heat lost during a door opening. We try to avoid putting any room temp or warm things in the fridge or freezer until they are running. We even try to time shopping so we get home off peak with the groceries. Heck we even turn off the ice maker during the week and only run it on weekends. I metered it at one point, but it adds quite a bit of power to make ice.

Darell here is a online calc that allows you to put in your energy cost and efficiency to compare gas, to electric, to what ever.

Comparison Calculator (I figured out the URL)

Ok you got me Darell, were all nuts

 

[Brock]

Bill beat me to the link.

Our current off peak rate is .0417
and current gas is 1.28 per therm

Our electric rates are supposed to go up soon, so it will likely swap back, but for now I am running electric water heat. I have a 40 gallon electric in front of my 40 gallon gas, the electric obviously only runs off peak. Right now I have the gas turned all the way down so I use it as a storage tank so I have about 80 gallons of hot water.

Also in the summer when electric wasn't cheaper I used the electric as a storage tank and circulated that water through a radiator and a fan. So the water got up to room temp from about 50F. Extra cooling for the house and pre-heating the water to the gas water heater.