My favorite science question:

Two sealed, insulated rooms, one has a fan running inside, the other, not.

Which room is cooler?

 

room heating. highest efficiency based on percentage.

Heat pumps aren't usually used for room heating but that's the most efficient option by a wide margin.

Something that uses electricity to process information, such as a computer, is more 'efficient' than a mere heater or light bulb. It's delivering the same watts of heat for watts consumed but you get a higher quality of energy for free in the process. It would take a while to explain the thermodynamic concept of quality, but I think you get the idea that a computer is somehow better than a lightbulb.

 

My favorite science question:

Two sealed, insulated rooms, one has a fan running inside, the other, not.

Which room is cooler?

So I am at a US Navy facility in Naples Italy and it was an unusually cold evening with the temperature about 35 degrees F. There was a strong wind off the Mediterranean so the wind chill temp was mid 20s. A technician asked me why the puddles of water in the parking lot weren't frozen. Uh?.....

Ron

 

My favorite science question:

Two sealed, insulated rooms, one has a fan running inside, the other, not.

Which room is cooler?

the room without the fan.

 

Heat pumps aren't usually used for room heating but that's the most efficient option by a wide margin.

Around here, that's usually what a device that is specifically called a "heat pump" is used for.

Whether they are more cost efficient is debatable (which is why they aren't in extremely widespread use) because they cost a lot more to install than electrical resistive heating and electrical energy is generally a lot more expensive than natural gas. Of course, all of that is location-dependent, so in some places heat pumps are much more popular than others.

One thing that I looked into a number of years ago was using geothermal heat pump and while I'd still like to do it, it's hard to justify on cost basis. We were looking at about $12,000 to install it. Currently we heat our home for about $10/year in wood (but a LOT of labor) and about $500/year in propane. The heat pump would increase our electrical usage, so we'd probably be lucky to save $300 to $400 a year. Considering that, if I had $12k to install the heat pump, if I could get about 4% real rate of return on an investment, that would endow our propane indefinitely, there simply isn't any percentage in the investment (particularly which such systems are NOT maintenance free over the long term).

 

Around here, that's usually what a device that is specifically called a "heat pump" is used for.

Years ago I lived in Chesapeak VA in an apartment duplex heated by a heat pump. Soon as the outside air got down in the mid 30s F or around 0 C. it was useless and blew cold air. At that point you hit a magic switch and tossed electric heater elements into the mix. You stayed warm finally but you got a hell of an electric bill.

A few decades ago out in the west Cleveland suburbs they built a community of all electric homes. There was a deal cut with the power company for huge discount power. This was supposed to be lifetime and as any power company deal things got ugly. When people tried to move and sell their homes the new owners would be hit with double and triple what the old rate was. This made selling your home difficult to impossible. That mess is still in the courts as electricity is the most expensive way to heat a home. We use natural gas fired forced air which is quite inexpensive around here and even my emergency generator is natural gas fired.

Ron

 

Years ago I lived in Chesapeak VA in an apartment duplex heated by a heat pump. Soon as the outside air got down in the mid 30s F or around 0 C. it was useless and blew cold air.

That's the beauty of the geothermal systems they install around here. The external reservoir is the ground water down about a hundred feet for so. From talking to the guy that was installing one of the systems, they drill down into the second aquifer (our well goes down and draws from the third). So year round your heat sink/source is a pretty constant temperature (which is apparently about 70°F here, quite a bit warmer than I was aware of). The heat pump is reversible, though the need for cooling in the summer is very minor, here.

If I were younger, I'd love to get us completely off the grid, either as primary with grid backup, or at least be capable of being completely off the grid as a backup. It wouldn't take that much. We don't get a whole lot of sun here, but I think we could get enough panels to handle our base load fairly well. Then I'd like to have a propane fired backup generator. Again, if I were younger, it would be neat to try to go for one year completely separated from the grid. But at my age now, I just have too many other things that are of higher importance to me.

 

By consensus, natural gas is the least expensive. Electric, the most expensive.
It is my second year in reverse: Canceled gas service and replaced the gas burner with electric heating
Now my gas service bills are non-existent. They used to charge me every month of the year with zero consumption, a minimum charge plus 'transportation' plus fees plus 'basic service' plus taxes plus whatever they felt adding to the bill.

Am still ahead for the year, spending less for heating even with electric heat, plus peace of mind about gas leaks.

 

Mussharraf Hossen Shoikot,

I doubt you realized what responses you'd trigger. In case the term "Heat pump" is unfamiliar to you, it is essentially an "air conditioner", but you use it to cool the outside air and the opposite side of the equipment discharges heated air into your area that you want heated.

The only way to get more heat out of an electrically powered heater than the amount of electrical power it directly consumes is to power a mechanism like a "heat pump", as it is actually moving heat from one area to another, and if installed correctly, all the mechanical inefficiency will be discharged as heat also, into your intentionally heated space.

 

Use electricity to run a heat pump to transfer heat from one area that doesn't need it to the place that does need it. You can get 300 - 400+% energy efficiency that way on energy input to thermal output.

Source of that claim?

 

Source of that claim?

<snipped the uncivil remarks>

http://www.powerknot.com/2011/03/01/cops-eers-and-seers/

 

Source of that claim?

That's how they work. They're like air conditioners, which typically move ~10 units of heat for each one consumed. Heat pumps are less efficient than air conditioners because of the operating conditions under which you specify their performance, but they're essentially the same.

 

That's how they work. They're like air conditioners, which typically move ~10 units of heat for each one consumed. Heat pumps are less efficient than air conditioners because of the operating conditions under which you specify their performance, but they're essentially the same.

<snipped remark regarding deleted content>

And thank you Wayne for your response.

I was under the same ideas that you have about air based heat pumps. Until I needed to replace my furnace. After spending time talking to the 'tech guys' at a company that sells tens of thousands of HVAC units a year all across the country to do it yourselfers, they talked me out of it. Unless, according to them, you go geothermal, in my area they only get somewhere between 150% efficiency. And are more , money to buy, less reliable over time, and more expensive to maintain and repair. That 150% vs a 96 t0 98% gas furnace. The payback for the heat pump wasn't realistic.

They would sell me one, but highly recommended not getting one. They also said that as an air conditioner they weren't as efficient as a standard unit. That they "looked good on paper" but in the area I live, which isn't really that extreme, they don't live up to the paper hype.

 

That they "looked good on paper" but in the area I live, which isn't really that extreme, they don't live up to the paper hype.

Ditto where I live. Nobody has one around here. They're very common about 300 miles south of me, in southern Illinois. I approached the TS's question as more of a theoretical question since there was nowhere near enough detail to provide a better answer. "Efficiency" could mean heat produced per dollar spent, and that's a very different question than BTUs per kWh or whatever.