Cheapheat

[OldCoot]

Originally Posted by tncruiser

... only a heat pump will give you more output than input...

I think that defies the First and Second Laws of Thermodynamics.

[tncruiser]

Originally Posted by dunnnc

I think that defies the First and Second Laws of Thermodynamics.

our quote is correct i should have said "a heat pump will use the 1500 watts more effciantly(sp) than a 1500 watt resistance type heater
as a side note laws 1 and 2 of thermodynamics have been recently modified do to a proposal put forth by al gore from here on out heat sources will be defined,regulated and taxed by an upgrade in a algoreythm
brianj

[5fulltime]

Originally Posted by tncruiser

1500 watts of heat = 1500 watts of heat only a heat pump will give you more output than input,the neat thing about cheap heat is it is a nice installation but is not any different than using a 20 dollar electric space heater
brianj

You could not be more wrong check out there web site. Thrie heater coil has three temp ranges:
1800 watts for a 30 amp service 16.5 amps on the one leg
3750 watts for a 50 amp service 16.5 amps per leg
5000 watt for a 50 amp service 21.5 amps per leg.

Also a gas is only 60% eff (40% out the flue) so 40,000 btu gives you 24,000 out and the gas furnace has a pre purge and post purge (total 2 1/2 min every cycle with no fire) so when you actually check the true sinsable heat over an hour so your true sensible btu an hour output is only 18,000. The 5000 Watt coil at 230 VAC (a true 50 amp service has 2- 115 VAC legs out of phase which gives you 230 VAC same as a house) is 17,500 btus (100% eff no pre or post purge) an hour or 98% of a 40,000 btu gas furnace.
My cheap heat system has heaterd my 38 foot 5th wheel with 5 slides to a comfortable 72 degrees inside when it was zero degrees outside.

[OldCoot]

Originally Posted by tncruiser

our quote is correct...

Beg to differ, your quote cannot be correct. It is impossible to create energy! If you input 'x' amount of energy, your output is 'x-?'

[5fulltime]

Originally Posted by dunnnc

Beg to differ, your quote cannot be correct. It is impossible to create energy! If you input 'x' amount of energy, your output is 'x-?'

Your wrong a heat pump by design is always over 100% eff the key is it doesn't make it, it takes the heat energy out of the outside air and raises it up to a usable temp ( by compression) and delivers it to the inside structor.

[OldCoot]

Originally Posted by 5fulltime

Your wrong a heat pump by design is always over 100% eff the key is it doesn't make it, it takes the heat energy out of the outside air and raises it up to a usable temp ( by compression) and delivers it to the inside structor.

http://en.wikipedia.org/wiki/Carnot_cycle:Every thermodynamic system exists in a particular thermodynamic state. When a system is taken through a series of different states and finally returned to its initial state, a thermodynamic cycle is said to have occurred. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. A system undergoing a Carnot cycle is called a Carnot heat engine, although such a 'perfect' engine is only a theoretical limit and cannot be built in practice.

[5fulltime]

Originally Posted by dunnnc

http://en.wikipedia.org/wiki/Carnot_cycle:Every thermodynamic system exists in a particular thermodynamic state. When a system is taken through a series of different states and finally returned to its initial state, a thermodynamic cycle is said to have occurred. In the process of going through this cycle, the system may perform work on its surroundings, thereby acting as a heat engine. A system undergoing a Carnot cycle is called a Carnot heat engine, although such a 'perfect' engine is only a theoretical limit and cannot be built in practice.

With a heat pump you put a dollar of energy in you get two to three dollars of heat energy into your building. Simple math

[OldCoot]

Originally Posted by 5fulltime

With a heat pump you put a dollar of energy in you get two to three dollars of heat energy into your building. Simple math

Don't disagree with the $$$. Just that you cannot get more energy out of a device than what you put in. Physically impossible.

[RJHuser]

Actually a heat pump does not creat heat, it transfers it from one place to another. An air conditioner is a heat pump in reality. It transfers heat from the interior of, say, a RV to the outside. In heating mode, it does the opposite, it transfer heats from the outside to the inside.

Even in very cold conditions, there is "heat" or thermal energy in the outside air. The heat pump "pumps" that heat using a phase changing fluid. Just like with water and steam. To convert water at atmospheric pressure and 212*F to steam at 212*F takes about 1000 BTUs, this energy comes from some source of heat, burning fuels or electricity heating an element. This energy is recovered when the steam changes back to water (condensation).

In a heat pump, the electrical energy is used to run the pump, also known as the compressor.

The coolent enters the compressor as a low pressure gas. It is then compressed, and then goes through the condenser where the high temperature high pressure gas transfers it's heat to the air passing through the condenser, causing a phase change to a high pressure moderate temperature liquid. This high pressure moderate temperature liquid enters the evaporator, where a nozzle or valve causes a sudden drop in pressure. This low pressure moderate temperature liquid absorbs heat and boils, turning back into a gas that is returned to the compressor, where the cycle repeats.

Now, in the summer, the condensor is outside and the evaporator is inside, so heat is transferred from inside to outside. In the winter the cycle is reversed, the condensor is inside and the evaporator is outside, so heat is transferred from outside ot the inside.

As said above, the electricity used in a heat pump is used to drive the pump (compressor) and fans, none (or a very small amount) is converted to heat energy. So, it is possible to get 3 to 6 BTUs of heat (or cooling) from each BTU of electricity used.

A very good decision oh how a heat pump works is here Heat pump - Wikipedia, the free encyclopedia

Rick

[Iggy]

Rick

Heat pumps are more inefficient as the outside temps drop closer to freezing to apoint that it is just a waste of electrical energy to produce very little heat. In a house with a larger condensor it is more efficient but with a small RV unit the condensor is way too small to make it worth while to use a heat source.


Drawbacks of air-to-air heat pumps are:

• loss of efficiency as temperature decreases below 6–7ºC
• higher initial purchase and installation cost than portable heaters
• air distribution is by fan, which can cause draughts and noise
• space is needed to install larger exterior consensor

[trell]

There is heat that can be take out of a atmosphere down to absolute zero(-460 degree) the Question is , is it feasible. Depend on your equipment it can be done @what cost who knows. Sometimes it not worth
the hassle.The cheapheat seem like it may be good alternative.Still in the investigation just seeing how cheap it can be.

[Witch Doctor]

Originally Posted by Iggy

Rick

Heat pumps are more inefficient as the outside temps drop closer to freezing to apoint that it is just a waste of electrical energy to produce very little heat. In a house with a larger condensor it is more efficient but with a small RV unit the condensor is way too small to make it worth while to use a heat source.


Drawbacks of air-to-air heat pumps are:

• loss of efficiency as temperature decreases below 6–7ºC
• higher initial purchase and installation cost than portable heaters
• air distribution is by fan, which can cause draughts and noise
• space is needed to install larger exterior consensor

Iggy you are correct, But Rick gave a great explanation on how they work. When the heat pump can not keep up a heat strip should kick on. A heat pump without a strip heat is not going to work when the temp outside drops to be unacceptable the strip should kick in auto if your stat will not reach the set pt. most stats have a 2 to 4 degree band. The whole point is that you can turn on the emergency heat which activates the heat strip (cheap heat). In commercial apps. you have a air handler then when you call for heat the electrical strips turns on, which creates your heat otherwise it is just cold air 24hrs. aday. I had a wildwood LE trailer. The ac unit roof top (not a h/p) came with a plug in heat strip connection as an option. Also a propane furnace. If I wanted heat from the roof top unit the heat strip and blower came on only. The same concept of cheap heat. The only thing is that you just had to buy the strip and plug it in where your filter is. All wired and set up already. The only thing is that strip heat pulls a lot of amps. So maybe I would have been able to put a 4kw strip in. Not very much but my trailer was only 19' at that time........ My new Rookwood doesn't have that option.....