Electricty Comsumption

Member Posts: 79 Age: 35

Over the last few weeks I have had quite a few discussions with other members of A-T and the GCCA forum about power consumption and usage. It got me to thinking.... What does our great hobby cost on a regular monthly basis?

Lets start off with a few basics you may already know. Your power provider measures your usage by the Kilowatt hour (kWh). I know out by me Commonwealth Edison charges $.08275 per kWh. All of our equipment has listed on it the wattage rating. With this info we can easily calculate what the cost of running a certian item will be.

Here is the formula for figuring out the monthly cost of an AC110. A few things to keep in mind here are 1. this formula calculates cost of running an appiance 24/7 for a month. We all know our heaters don't stay on all day and night. 2. This formula isn't 100% accurate as there are many variables that can have an effect on the outcome. 3. This formula will however get you into the ball park as to your costs.

The formula is: Wattage/1000 X your cost per kWh X 24hrs X 30 days per month.
So I looked up the AC 110 power filter and it uses 14 watts.
14 / 1000 X .08275 X 24 X 30= $.8341.

Thats only 83 cents a month to run an AC110. I was quite supprised and the cheapness of running one of these. I looked at some heaters and a 300w heater comes out to be about $17.87 a month, and that is if it stayed on 24/7, which we all know they don't. Some 48in light bulbs run about 32 watts each. That comes out to $1.90 a month if they are on 24/7.

Keep in mind that this forula won't be 100% accurate as there are too many variables involved. I have found and known that the majority of our expenses are tied to heating costs. Which is why if you have multiple tanks in a well insulated room you can heat the room with 1 heater and save yourself a bundle of cash.

Incase your equipment dosen't give you a wattage rating but instead it gives you a amperage rating you can multiply the Amps X Voltage (120V) to get your wattage.

Any comments are welcome.
Keeper

Subject: Re: Electricty Comsumption Sat May 30, 2009 4:49 pm

Very interesting, thanks for sharing....I have read similar discussions in the past and came to my own conclusion that it costs me on average about 5-7 dollars a month per tank.

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Subject: Re: Electricty Comsumption Sat May 30, 2009 6:22 pm

Good info! All in all it seems pretty cheap to run a tank.

Subject: Re: Electricty Comsumption Mon Jun 01, 2009 7:33 pm

DragonKeeper wrote:

Keep in mind that this forula won't be 100% accurate as there are too many variables involved. I have found and known that the majority of our expenses are tied to heating costs. Which is why if you have multiple tanks in a well insulated room you can heat the room with 1 heater and save yourself a bundle of cash

Which is pretty close to what I figured it at. Say a heater is on 50% of the time, that's app. $9 a tank, and with 40+ tanks goin' in... The heater I bought for my room is 3500 watts and advertises it'll raise the electric bill app. 30% at 82°. I haven't seen that, app. 26% is the largest I've seen. $35/month for one heater or $360 +/ month for 40+ heaters. Even if an aquarium heater is on only 25% of the time, that's still $180/month. If the tank heaters are on 10% of the time, I break roughly even and still don't have to worry 'bout electric outlets for 'em all.

Great post, Dragonkeeper.

WYite

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Member Posts: 79 Age: 35

Best way to curb heating cost is to insulate the heck out of the room. The more heat that stays in the room the less the needs to be generated.

Keeper

Subject: Re: Electricty Comsumption Tue Jun 02, 2009 12:47 pm

The other thing that works is more larger tanks. The heat will stay in a larger volume of water a lot longer than in a small tank. Plus it is another excuse to get a bigger tank... Wink

Member Posts: 79 Age: 35

dirtydawg10 wrote:

The other thing that works is more larger tanks. The heat will stay in a larger volume of water a lot longer than in a small tank. Plus it is another excuse to get a bigger tank... Wink

I am not completely sold on this theory yet. Larger volumes of water generally means more surface area. More surface area means more heat transfer (whether into the tank or out). Heat can't transfer if it has no where to go.

Heating a well insulated room with a efficient electric or natural gas heater controlled by a quality digital thermostat will in the long run save you much more money in heating costs. Keep in mind too that when that larger volume of water looses enough heat to turn on the heater it takes longer to warm it up to temp.

This is all just my opinions which are based on some facts and personally experiences I have had over the years.

Keeper

Subject: Re: Electricty Comsumption Tue Jun 02, 2009 1:46 pm

If you over insulate a room and dont let it breath properly your gonna be in bigger trouble than electricity consumption with the mold issue you will breed! Mold starts from the inside of the board also so it will take alot longer to notice.

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Subject: Re: Electricty Comsumption Fri Jun 05, 2009 7:03 pm

DragonKeeper wrote:

I am not completely sold on this theory yet. Larger volumes of water generally means more surface area. More surface area means more heat transfer (whether into the tank or out). Heat can't transfer if it has no where to go.

Heating a well insulated room with a efficient electric or natural gas heater controlled by a quality digital thermostat will in the long run save you much more money in heating costs. Keep in mind too that when that larger volume of water looses enough heat to turn on the heater it takes longer to warm it up to temp.

This is all just my opinions which are based on some facts and personally experiences I have had over the years.

Keeper

You're correct in that larger volumes mean more surface area; however, a smaller tank has more square inches of surface area per gallon than a larger tank. For example, a 225 gallon tank is 72" long x 24" wide x 30" deep, for a surface area of 9216 sq inches. Divide that by 225 and ya have 41 sq inches of surface area per gallon. A standard 10 gallon tank is 20" long x 10" wide by 12" deep, for a surface area of 1120 sq inches. Divide that by 10 and ya get 112 square inches of surface area per gallon. All other things being equal, the water in the smaller tank will contact a surface area more often than the water in a larger tank and therefore will lose heat faster.

This includes the sides and bottom. Heat transfer does not occur as fast through the sides or bottom as it does from the open top, due to the insulating effect of the glass, but does occur.

By all other things being equal, I'm referring to turnover rate, ambient temperature and humidity, and how well the top is sealed, just off the top of my head. A higher flow rate will turn water over faster and increase how often the water contacts a surface, increasing heat transfer. An open tank will lose heat faster than one with a tightly sealed lid due to air circulation and increased evaporation. Humidity will affect heat loss in the aquarium water; high air humidity decreases the amount of water the air can hold, so evaporation slows. Evaporation is a major conduit for heat transfer out of aquatic systems. Ambient temperature will also affect heat loss on a tank, as heat will transfer faster to the cooler air around it. Heat will travel slower from a tank that is 78° to air that is 76° than it will travel from a tank that is 78° to air that is 68° due to the higher thermal gradient between the two contacting surfaces in the latter scenario.

Put all these factors together, as well as others that I know I forgot, and that is what determines how much energy it takes to keep a tank a t a steady temperature. A larger tank is affected less by these issues than a smaller tank due to the lower surface area:gallon ratio.

WYite

_________________
One can never have too many fish tanks.

Member Posts: 79 Age: 35

detroitfish wrote:

If you over insulate a room and dont let it breath properly your gonna be in bigger trouble than electricity consumption with the mold issue you will breed! Mold starts from the inside of the board also so it will take alot longer to notice.

Good reminder. Completely forgot about the mold issue. Most fish rooms that are heated and heavily insulated are also fitted with a heat exchanger or vented with a timer fan. My personal fishroom of the future will be heated by a high efficiency furnace and vented with a heat exchanger.

Wyomingite wrote:

DragonKeeper wrote:

I am not completely sold on this theory yet. Larger volumes of water generally means more surface area. More surface area means more heat transfer (whether into the tank or out). Heat can't transfer if it has no where to go.

Heating a well insulated room with a efficient electric or natural gas heater controlled by a quality digital thermostat will in the long run save you much more money in heating costs. Keep in mind too that when that larger volume of water looses enough heat to turn on the heater it takes longer to warm it up to temp.

This is all just my opinions which are based on some facts and personally experiences I have had over the years.

Keeper

You're correct in that larger volumes mean more surface area; however, a smaller tank has more square inches of surface area per gallon than a larger tank. For example, a 225 gallon tank is 72" long x 24" wide x 30" deep, for a surface area of 9216 sq inches. Divide that by 225 and ya have 41 sq inches of surface area per gallon. A standard 10 gallon tank is 20" long x 10" wide by 12" deep, for a surface area of 1120 sq inches. Divide that by 10 and ya get 112 square inches of surface area per gallon. All other things being equal, the water in the smaller tank will contact a surface area more often than the water in a larger tank and therefore will lose heat faster.

This includes the sides and bottom. Heat transfer does not occur as fast through the sides or bottom as it does from the open top, due to the insulating effect of the glass, but does occur.

By all other things being equal, I'm referring to turnover rate, ambient temperature and humidity, and how well the top is sealed, just off the top of my head. A higher flow rate will turn water over faster and increase how often the water contacts a surface, increasing heat transfer. An open tank will lose heat faster than one with a tightly sealed lid due to air circulation and increased evaporation. Humidity will affect heat loss in the aquarium water; high air humidity decreases the amount of water the air can hold, so evaporation slows. Evaporation is a major conduit for heat transfer out of aquatic systems. Ambient temperature will also affect heat loss on a tank, as heat will transfer faster to the cooler air around it. Heat will travel slower from a tank that is 78° to air that is 76° than it will travel from a tank that is 78° to air that is 68° due to the higher thermal gradient between the two contacting surfaces in the latter scenario.

Put all these factors together, as well as others that I know I forgot, and that is what determines how much energy it takes to keep a tank a t a steady temperature. A larger tank is affected less by these issues than a smaller tank due to the lower surface area:gallon ratio.

WYite

Good point. Didn't even look at it that way!

Keeper

Subject: Re: Electricty Comsumption Wed Jul 08, 2009 1:54 pm

Right. I won't go into it too much but at one point I used.

1.1 something watt/h is like 1kcal/h.
1cal raises the temp of 1L of water.
A 300W heater is therefore capable of 2600 degrees per hour.

Adapting some REALLY hokey math used for swimming pool heating systems 36 degrees per square foot would be lost per hour, ignoring the loss through the sides and back because the numbers are tiny (and it makes life easier).

Ambient temp is currently 21 degrees. As an example I worked out that with a 3 foot tank of 120L you'd need to overcome about 110 degrees of heat loss and you'd needing to supply 120L with 3 degrees per hour means that you'll need an additional 360 degrees of heating for a total of 470 degrees of heating. As the heater can supply 2600 degrees per hour it will heat 43 litres by one degree per minute meaning that a 300W heater in a 3' 120L tank will remain on for 10.9minutes at that ambient room temperature.

Heat loss was mostly based upon the heat loss through evaporation and my tanks are kept covered. The amount lost through radiation is much lower. Also there a non liner increase in heat loss as the temperature disparity widens which would require constant adaptations in the formula for true accuracy. The calculations for heat loss through the glass was made using the heat loss through steel and modifying based upon the difference in R values for glass and steel. Typically it is about 1/3 as conductive so that is what I used. Insulation would seem very effective if you can get polystyrene on tank bases and maybe paint/foil coat sides. Acrylic tanks lose heat slower than glass.

The point I am trying to make is that there are many many variables to correct if you wanted a truly accurate costing. Add a few percentage to the surface area for heat loss due to surface agitation?

I use this 11minute per hour rule for all my costing during summer months and double it for winter months. It gives me a very rough average but it is better than grabbing say. 50% of the time. I've recently 'culled' my heaters and filters and pumps and things for a more energy lite setup and increased my water change frequency. I've got a total of 700W of heating, 70W of filters, 7W of pumps for a total of £12.50 per month, another £1.50ish for 105W of lights at 6 hours per day. I used to run almost 1800W of junk!