Thick silver styrofoam probably the best idea.
Use a small 12V heat blanket the first week it's cold so the cats learn that it's warm in there.
Then only use it the few nights when it really gets cold, should only have to charge the battery 4-6 times that season and it's not to much of hassle.
So how does one fit in Amps or Volts in reference to heat? Not very directly...
+++++++++++++++
Use the compost pile for heat and insulation, then the battery can run a Propeller driven monitor and maybe control a fan.
BTU and Joules are the same thing, give or take a scaling constant of 1054. A measure of energy.
BTU/s and watts are the same thing, give or take a scaling constant. A measure of energy consumption.
BTU is not BTU/s and so Joules is not Watts.
In terms of amps and volts we have:
watts = amps * volts
heat in joules = amps * volts * time in seconds
How easy could it be?
Of course that says nothing about any temperature rise.
But we have:
H = Cp * M * delta T
Where delta T is the temperature rise in degrees C, H is the energy input in joules, Cp is the specific heat capacity in J/kg x degrees C and M is the mass in kilograms
So to warm a typical 4Kg cat by 1 degree C we need approximately:
H = 4000 * 4 * 1
Or 16000 joules.
Or 16000 watts for one second.
Ouch! That does not sound right. Anyone care to check?
Edit: Well that is only about 260 watts for a minute, perhaps not so crazy.
Well now.... If it was me and I wanted to keep my furry little friends warm during the winter months... First I would provide an insulated shelter, then I would lay down some heat tape and cover it with an inch or two of sand or dirt, and then cover it with a blanket. The heat tape would then be connected to a thermostatically controlled relay, which would only supply power when the shelter temperature dipped below a preset level.
I put out the box yesterday, checked on it today and both the cats are inside it. So the hardest part is done which is getting them to go inside. The rain helped. This is a quick test box to see if they would go in. It has 1/2" foam board on all sides, top and bottom with a blanket. If they stick with it I will make some improvements and look at the heat options. This area is under trees and there would not be much direct sunlight.
That's just about exactly what I was suggesting (well, I don't see a blanket). Is that a Rubbermaid storage container? It looks like one (I have a bunch of 'em)
As long as the shelter is dry, cats can use their own body heat to keep warm. My cats simply prefer a piece of glass wool to lay on, even though they have access to a well insulated cat house with heated floor.
Never seen they get itchy or feel any uncomfortable with it. The glass wool have to be replaced once in a while as it gets worn out. But any insulation material would work as long as it is soft enough. On this picture from my barn you can see the piece of glass wool to the right in the background couch.
I just think pragmatically of heat generated in Watts, and avoid all that conversion.
1054 Watts is roughly what my little floor heater does.
30 Watts is what my soldering iron puts out.
5 Watts is unlikely to burn me, but is what 1 amp at 5 volts will generate.
BTUs, Joules, Calories, and Columbs just distract me from have a means for comparison. After all, any heat we feel is going to Watts or BTU/s.
Even a watt can burn you if it is concentrated on a small area like that of a SOIC regulator chip or mosfet. The tiny burn like that is not much of an injury, but can be a painful nuisance if it is on a finger tip or similar area.
BTW thanks for the explanation Phil, so whether it is a heating pad or light bulb, a watt will be the same amount of heat. I never knew that.
Heat is the same, but keep in mind heat rises, so a light bulb will give a nicely warmed roof.
- best idea is draft & weather proofing, insulation and thermal inertia - simple thermal mass is cheaper than batteries.
When I first read this, my thoughts were with a water heater / exchanger configuration, but that won't be cheap. Atwood makes water heaters that might be suitable but they'd require both 12V and LPG to operate. On the up-side to that, they have electronic start models that don't require a permanent pilot flame so wouldn't consume LPG until heat is needed.
Circulate the liquid around the battery too, after passing the liquid through the 'cat motel' and that'd help keep it warm enough to not adversely affect its output.
Properly set up, the liquid could probably auto-circulate and not require additional power drawn from a pump, but even then, the pump wouldn't run very long since likely you'd only be trying to maintain a consistent temperature at the bedding, so I think that LPG would be the biggest cost involved in maintaining it, and my experience with RV's suggests the battery should last at least a month, if properly selected, like a larger marine / RV deep-cycle battery, and a 30# (7.5 gallon) LPG tank should last at least that long too, provided the system isn't running continually- I've seen homes with 500 gallon LPG tanks go for weeks to months heating both water and air.
WRT the liquid, water with either propylene glycol or glycerol based antifreeze should be fine and both are non-toxic. Though, the system should be flushed at least a couple times a year.
Later, started thinking about making the dwelling subterranean. Then you get the benefit of having a relatively well insulated space with temperature buffering caused by the earth itself. Keeping the entrance unobstructed could be an issue, as could flooding though a sump pump may be an option. Maybe half under / half above ground...? And a wind-break surrounding it might not be a bad idea.
Further thought got me thinking since solar doesn't appear to be an option, what about a small wind turbine? It could be mounted high enough to not deter the cats from the dwelling, and might give enough power to keep the battery charged at least enough to extend any change-out periods substantially, if not eliminate the need.
A smallish BLDC fan could provide intermittent air circulation- one or two minutes should help clear any stale air.
Dang, I'm starting to think I'm designing my future home.
I got a very interesting bit of take away knowledge when it occurred to me that a compost pile might provide a sustained heat source for the whole winter.
The bio-chemical process actually outperforms any battery and is more reliable than the sun. Enzymes and digestion are still not really well understood. Linus Pauling claimed that human metabolism relies on something between 20,000 and 30,000 enzymes in his General Chemistry text.
So, the bio-chemical source of heat really have a lot to offer over just burning fuel or conversion of electricty to heat. It is sustainable over many months as a low rate.
+++++++++++++
Greeks and Romans used large and long subterrainean tunnels to provide air in buildings that was both cool in the summer and warm in the winter. If you have enough property, this solution still can cut your a/c bills in the summer and your heating bills in the winter.
It was a post before yours that mentioned anti-freeze.
Personally, I doubt the cats need all that much help. It's Atlanta after all, not Alaska. Probably a cheap plastic storage container or two from Walmart with old blankets inside would be plenty good enough.
Wait a minute, we're talking about Atlanta GA ???????
A quick Google shows that it rarely even gets to freezing.
Seriously, as I mentioned, a couple of those plastic milk crates with some insulation, off the ground in 2x4 or some bricks, small entryway with maybe an old towel as a hanging door, and those should be some very contented cats.
--EDIT-- Ahh, I see you did something similar. I wanna see some more pictures of this during the winter.
Atlanta gets below 32F on quite a few days, and has many weeks in the freezing range. It is not that they wont survive, but if it is a simple matter to put a battery, some rigged up controller and a battery, then why not. Lots of good ideas here, but solar and underground(or under compost) are not options. City property so I don't want to modify the land. Some lessons over the first box I built that they never went in: The box must be big enough or they wont go in it. I also included a front and rear door on this one, as I read they prefer a rear escape route in their house, else they may not go in. Some great info here on heat and watts and amps, so that helps out a lot to make a plan.
Although this is an interesting idea I still think the simplest and best solution is to provide an insulated shelter and fuel for the cats to produce their own heat. If they can survive an Ontario winter where we get weeks of minus 20 to 30 degrees celsius (-4 to -22 farenheit) then they will survive in Atlanta. Outfitting the shelter with temperature and occupancy sensors and collecting the data would make for an interesting project.
Comments
Re: 100% efficiency. Yes, that's what you said. Missed that comment in your post somehow. Too many interruptions and not enough coffee this morning.
Use a small 12V heat blanket the first week it's cold so the cats learn that it's warm in there.
Then only use it the few nights when it really gets cold, should only have to charge the battery 4-6 times that season and it's not to much of hassle.
http://www.ask.com/science/many-volts-joule-equal-91376d83ed0d9423
Amps x Volts = Watts
1 BTU = 1054 Joules
1 BTU/s = 1054 Watts
So how does one fit in Amps or Volts in reference to heat? Not very directly...
+++++++++++++++
Use the compost pile for heat and insulation, then the battery can run a Propeller driven monitor and maybe control a fan.
I don't understand what you are getting at.
BTU and Joules are the same thing, give or take a scaling constant of 1054. A measure of energy.
BTU/s and watts are the same thing, give or take a scaling constant. A measure of energy consumption.
BTU is not BTU/s and so Joules is not Watts.
In terms of amps and volts we have:
watts = amps * volts
heat in joules = amps * volts * time in seconds
How easy could it be?
Of course that says nothing about any temperature rise.
But we have:
H = Cp * M * delta T
Where delta T is the temperature rise in degrees C, H is the energy input in joules, Cp is the specific heat capacity in J/kg x degrees C and M is the mass in kilograms
So to warm a typical 4Kg cat by 1 degree C we need approximately:
H = 4000 * 4 * 1
Or 16000 joules.
Or 16000 watts for one second.
Ouch! That does not sound right. Anyone care to check?
Edit: Well that is only about 260 watts for a minute, perhaps not so crazy.
Heat tape supplier -> icedamcompany.com/product-category/ice-dam-heat-cables/
Never seen they get itchy or feel any uncomfortable with it. The glass wool have to be replaced once in a while as it gets worn out. But any insulation material would work as long as it is soft enough. On this picture from my barn you can see the piece of glass wool to the right in the background couch.
1054 Watts is roughly what my little floor heater does.
30 Watts is what my soldering iron puts out.
5 Watts is unlikely to burn me, but is what 1 amp at 5 volts will generate.
BTUs, Joules, Calories, and Columbs just distract me from have a means for comparison. After all, any heat we feel is going to Watts or BTU/s.
Even a watt can burn you if it is concentrated on a small area like that of a SOIC regulator chip or mosfet. The tiny burn like that is not much of an injury, but can be a painful nuisance if it is on a finger tip or similar area.
- best idea is draft & weather proofing, insulation and thermal inertia - simple thermal mass is cheaper than batteries.
Circulate the liquid around the battery too, after passing the liquid through the 'cat motel' and that'd help keep it warm enough to not adversely affect its output.
Properly set up, the liquid could probably auto-circulate and not require additional power drawn from a pump, but even then, the pump wouldn't run very long since likely you'd only be trying to maintain a consistent temperature at the bedding, so I think that LPG would be the biggest cost involved in maintaining it, and my experience with RV's suggests the battery should last at least a month, if properly selected, like a larger marine / RV deep-cycle battery, and a 30# (7.5 gallon) LPG tank should last at least that long too, provided the system isn't running continually- I've seen homes with 500 gallon LPG tanks go for weeks to months heating both water and air.
WRT the liquid, water with either propylene glycol or glycerol based antifreeze should be fine and both are non-toxic. Though, the system should be flushed at least a couple times a year.
Later, started thinking about making the dwelling subterranean. Then you get the benefit of having a relatively well insulated space with temperature buffering caused by the earth itself. Keeping the entrance unobstructed could be an issue, as could flooding though a sump pump may be an option. Maybe half under / half above ground...? And a wind-break surrounding it might not be a bad idea.
Further thought got me thinking since solar doesn't appear to be an option, what about a small wind turbine? It could be mounted high enough to not deter the cats from the dwelling, and might give enough power to keep the battery charged at least enough to extend any change-out periods substantially, if not eliminate the need.
A smallish BLDC fan could provide intermittent air circulation- one or two minutes should help clear any stale air.
Dang, I'm starting to think I'm designing my future home.
The bio-chemical process actually outperforms any battery and is more reliable than the sun. Enzymes and digestion are still not really well understood. Linus Pauling claimed that human metabolism relies on something between 20,000 and 30,000 enzymes in his General Chemistry text.
So, the bio-chemical source of heat really have a lot to offer over just burning fuel or conversion of electricty to heat. It is sustainable over many months as a low rate.
+++++++++++++
Greeks and Romans used large and long subterrainean tunnels to provide air in buildings that was both cool in the summer and warm in the winter. If you have enough property, this solution still can cut your a/c bills in the summer and your heating bills in the winter.
Wait a minute, we're talking about Atlanta GA ???????
A quick Google shows that it rarely even gets to freezing.
Seriously, as I mentioned, a couple of those plastic milk crates with some insulation, off the ground in 2x4 or some bricks, small entryway with maybe an old towel as a hanging door, and those should be some very contented cats.
--EDIT-- Ahh, I see you did something similar. I wanna see some more pictures of this during the winter.
I agree, thats a pretty darn nifty idea. Only problem in this case is that its not his property, and isn't there a possibility of suffocation?