EcoRenovator  

Go Back   EcoRenovator > Improvements > Conservation
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
Thread Tools Display Modes
Old 02-21-13, 10:03 AM   #1
Drake
DIY Guy
 
Join Date: Jan 2011
Location: Mpls,MN
Posts: 315
Thanks: 2
Thanked 17 Times in 17 Posts
Default Electric resistance heat efficiency?

Is there any real difference in efficiency of types of electric resistance heaters for on demand zone heating a room?

Drake is offline   Reply With Quote
Old 02-21-13, 02:40 PM   #2
Daox
Administrator
 
Daox's Avatar
 
Join Date: Aug 2008
Location: Germantown, WI
Posts: 5,482
Thanks: 1,117
Thanked 370 Times in 301 Posts
Default

Nope. All electric resistance type heaters are 100% efficient.
__________________
Current project -
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
&
To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
Daox is offline   Reply With Quote
Old 02-21-13, 03:56 PM   #3
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
Thanks: 241
Thanked 165 Times in 123 Posts
Default

I agree with Daox,

All resistance heaters have a COP of 1.00 by definition. This would include any device that asserts it is an infrared high efficiency heater ("Amish Heaters"). One kW = 3415 BTU. And if each kW costs ten cents ($0.10 - about the national average, $1 gets you ~34,000 BTU.

Sadly, some assert that resistant heat is 100% efficient compared to a high efficiency gas furnace ~94% efficiency. What they do NOT tell you is the energy cost of the fuel.

The above calculation, which gives you the cost of heat per $ of fuel is the best way I know of comparing apples to apples.

If a heat pump has a COP (coefficient of performance) of 4, then for each $ of electricity cost (@$0.10) would be 136,000 BTU/$. This is why heat pumps work so well.

Incandescent light bulbs are essentially resistance heaters as ~ 90%+ of the electrical energy goes to create heat.

By contrast, LED bulbs have the opposite (higher) efficiency with very little heat and lots of light (~90%).

Steve
__________________
consulting on geothermal heating/cooling & rational energy use since 1990
stevehull is offline   Reply With Quote
Old 02-21-13, 04:56 PM   #4
Drake
DIY Guy
 
Join Date: Jan 2011
Location: Mpls,MN
Posts: 315
Thanks: 2
Thanked 17 Times in 17 Posts
Default

Thanks, that is what I believed but marketing people can really get you to question what you think you know.
Drake is offline   Reply With Quote
Old 02-21-13, 08:20 PM   #5
kabutomushi
Kabuto
 
Join Date: Mar 2010
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Incidentally, even with incandescent bulbs, aside from the small amount of light that escapes from your windows, the entire amount of energy that is emitted as visible light (that is the missing 5% when we say they are 95% heat emitters) almost immediately is converted to heat energy after it strikes an object and is absorbed. The re-release of excess energy in the struck object will be--ta ta, long-wave, i.e. heat radiation. So even incandescent lights are 100% efficient--all but window light leakage is almost immediately released as heat.

So also it is with the LEDs. If an LED is 5 watts, that is the amount of heat it ultimately contributes to your heat budget, except for leaked visible light. Of course, your windows leak long-wave radiation as well...

This logic continues to virtually all of your electrical usage with the exception perhaps of your wireless router--your washing machine contributes the wattage almost entirely as heat into your house. Of course your electric range, and your refrigerator and TV do, too. In effect, in each case it is energy being released into an almost closed system, except that portion which leaks out of the enclosure. So if you add organized energy (electricity) to your house, it eventually shows up in its disorganized form--as heat.
kabutomushi is offline   Reply With Quote
Old 02-25-13, 02:00 PM   #6
NiHaoMike
Supreme EcoRenovator
 
NiHaoMike's Avatar
 
Join Date: Oct 2008
Location: Austin, TX
Posts: 1,131
Thanks: 15
Thanked 249 Times in 235 Posts
Default

Reflector incandescent lamps make great heaters. The actual amount of heat coming off is about the same as other incandescents, but it feels much more intense because it's focused. Use a dimmer and you'll be able to control the heat as well as prolong the service life.
__________________
To my surprise, shortly after Naomi Wu gave me a bit of fame for making good use of solar power, Allie Moore got really jealous of her...
NiHaoMike is offline   Reply With Quote
Old 02-25-13, 02:09 PM   #7
Ryland
Master EcoRenovator
 
Join Date: Mar 2009
Location: Western Wisconsin.
Posts: 913
Thanks: 127
Thanked 82 Times in 71 Posts
Default

I disagree that all electric heaters are the same.
infrared heat will make you feel warm with fewer watts being used, that is why infrared heaters are used for keeping people warm in out door seating, in large poll buildings and even in large stores, they don't care as much about heating the air as they do about heating the people and objects.
Ryland is offline   Reply With Quote
Old 03-12-13, 11:22 AM   #8
servant74
Lurking Renovator
 
servant74's Avatar
 
Join Date: Jul 2012
Location: Near Nashville TN
Posts: 6
Thanks: 2
Thanked 1 Time in 1 Post
Default

Yep, they all produce the same amount of heat from the same amount of power.

The difference is how the heat is delivered. Conductive heat, like from a stove top, is best if you are in direct contact like a pan on a stove top. Most of us don't snuggle up to a stove.

So Convection (even with forced air) is normally moving the air past the heating element, and then you get heated from the air.

There is also radiant heating, like infrared heaters use. Yes, they warm up, but you sense the heat more directly without heating the air between you and the heater as much. This is what 'heat lamps' are.

The latest rage are 'heat pumps', where you use the energy to get, say a SEER of 10, is supposedly efficient enough to 'collect' 10 watts of heat for every 1 watt it uses, and allows you to re-deposit the heat elsewhere. ... This is basically a refrigerated HVAC unit in reverse. ... This is also why 'heat pump' water heaters cool the room where they are located. So if you use them, putting heat pump water heaters in your conditioned space makes sense to me (but that could be argued differently too).

I hope that helps.
servant74 is offline   Reply With Quote
Old 03-12-13, 01:49 PM   #9
workaholic
Lurking Renovator
 
Join Date: Jan 2011
Location: evansville, indiana
Posts: 18
Thanks: 1
Thanked 1 Time in 1 Post
Default

My 20 year old propane water heater gave out last summer and I went shopping for water heaters. The propane models were predicting 513$/ year energy costs while conventional electrics were I think 508$/yr. Then i spied the heat pump type. estimated energy cost 295$/yr. The purchase price was around 400$ more but that's a 2 yr payback. When we got it home my wife looked and found that our electric company was giving a 350$ rebate! It works fine and seems to keep up with my 4 person household. Since it takes heat out of the room air and it is located in the same room as the furnace/air conditioner I cut a hole in the return ducting so the a/c when running would suck cool air out of the utility room and distribute it throughout the house. I only run it on heat pump mode during the summer cooling months, in the winter I run on conventional electric resistance mode. My theory is that the heat i take out of the air to heat my water needs to be replaced by heat from my propane furnace.
__________________
If there are two ways to do a job always choose the hardest; it'll take twice as long but you will learn twice as much.
workaholic is offline   Reply With Quote
Old 03-12-13, 02:01 PM   #10
JYL
Heat recoverer
 
Join Date: May 2011
Location: Quebec, Canada
Posts: 17
Thanks: 0
Thanked 2 Times in 2 Posts
Default

All electric heater generate the same amount of heat.

However, the thermostat governing the heater might make a sensible difference. Older mechanical thermostat might increase the heating cost by 15% and sometime much more depending on the characteristic of the enclose area. Furthermore, the comfort is much less generally.

Unit without FAN also permit a High quality electronic thermostat to make the room much more comfortable by keeping the heat element at a lower "Average temperature". What it means is that the heater is generally warm to the touch -- instead of being scorching hot.

I am in Quebec (where over 73% of the heating is by baseboard heating), so these type of thermostat are available at any hardware store (probably 10 brand of them). Elsewhere in US, I was able to find some of the HONEYWELL TH1xx series.

In any case, read the instruction carefully: You might need to inform the thermostat of the presence of a motorized FAN. Some assume the FAN exist -- and go ON/OFF by default -- these are not as comfortable. Some assume NOFAN -- and go proportional by default -- those will kill a fan motor on short order if you fail to reprogram them.

Actually, Honeywell did purchase a Quebec company call AUBE... You might get almost all model from their line-up under the HONEYWELL brand name -- Visit Aube Technologies inc. for more information

JYL is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 09:06 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Ad Management by RedTyger
Inactive Reminders By Icora Web Design