Gas or Oil?

[me]

OK

Can one also cool and use AC using gas as the energy source?

Just curios

[John Hines]

Sort of, one can setup a refrigeration cycle, using heat to provide the cooling, however you still electricity to move the air.

They used to have gas powered fridges for example, but they don't move air.

[Bill Seurer]

Of course you can zone ANY heating.

[John Gilmer]

Well, "modern" heating systems also require electric power.

(At one time many gas furnaces had "milivolt" type gas valve which used the small amount of power generated by the pilot light on a "thermpile" to power the thermostat circuit. If the electric was not working, the overtemperature sensor would cut the gas. Thus, you could get a little heat if you had gas but no electricity. Today, most gas water still work that way so if the power fails you can still fill your hot water bottle and take a hot bath.)

Up until the 70s the gas companies were still pushing gas central air conditioning systems. But when the gas shortages hit, they gave up on efforts to create new demand. Without the gas companies behind them, the makers of smaller gas cooling appliance (& AC) gave up the fight.

The "absorption" type of gas (or any heat source) water chillers (for LARGE commercial systems) are still being made but except for large industrial installations that use process steam they just aren't cost effective.

[David L]

"John Gilmer" wrote in news:4181beaf$0$ [e-mail]:

FWIW, my original post specified gas or oil. That's all I'm considering.

Any other comments on my original question?

[v]

So does my hot water baseboard system.

ANY heating system that uses a thermostat is supposed to only supply heat WHEN needed - there is nothing inherently more accurate about a thermostat controlling a resistance heater, in fact the ones mounted on the heaters themselves have additional problems from being both down on the floor, AND near to the heat source.

As to WHERE, there can indeed be some issues when trying to use a duct system optimized for cooling, for heating purposes. However, either a ducted or baseboard system actually designed for heating, also puts the heat where it is needed.

As for cost to operate - do the calcs. There is NO WAY that resistance heating can provide btus for less $, in any place with normal market electrical rates. This has not changed in the 30 years that I have been paying attention to the issue. It is inherent in the "system".

In a primarily cooling climate like FL or maybe So. TX, etc., if one is looking at capital costs, electric heaters can make sense as they will seldom be used, so go for the cheapest up-front cost.

-v.

[v]

Yes - and do *YOU* know what a heat pump does when it actually gets COLD out instead of just cool??? It switches over to its electric resistance backup! At the times of highest use, it becomes electric resistance heat.

Heat pumps work fine in mild climates like VA or further south. In New England they don't work out that well, too much time with the backup on. (Some people have fuel burning backup - but then its not "all electric" any more.) The cooling function of a heat pump (which as we all know is just a reversible "air conditioner" is also not so sought after in colder climates, where heating is the important load. Thus, my observation is that heat pumps are relatively rare in the North.

-v.

[Charles Spitzer]

a few years ago when i last investigated, you could get an ac unit that had a gas powered generator in it that produced the power to drive the normal ac unit in the other half of the unit.

[v]

No.

It takes a certain number of btus to heat a given area to a given temperature. Electric resistance btus are more expensive than fuel burning btus. The only way this seems to make sense, is similar to the analagous artificial argument made for gas fireplaces vs. central heat - someone compares heating the whole house, to only heating a small portion of the house. Of course heating a smaller area is less money, if all else is equal.

If you compared the same sized zone, it would still be cheaper to heat it with a properly sized fuel burning appliance. This can become ridiculous if one defines down the zone so much that there is no furnace or boiler that small - and set up a hypothetical to make the electric resistance come out on top - but in any "normal" application, the fuel burning btus are cheaper.

BTW, there is another issue - personally, I find that forced air heat is poor from a comfort standpoint - either blows hot or cold. That is why I prefer baseboard. But baseboard doesn't have to be electric. Comparing electric baseboard to fuel burning forced air is therefore also not comparable - you should compare to electric forced air, which has been done but is very rare by itself, but IS what happens when a heat pump system has to switch to its electric backup.

-v.

[Bill]

Here in Vermont where the tree huggers took over, we don't seem to build anything we need. We do have a contract with Hydro Quebec. Lets look at the electric bill I just paid today. Over in the corner of the bill is a box labeled Current Month Average Cost. It comes to 0.133, or

13.3 cents per KWH

I can't afford electric heat with those rates...

Bill

[John Gilmer]

I think I saw something about that in Popular Science (or variation thereof.) IF you didn't count the cost of the generator set it was about break even. But the gas engine would need the oil changes every few weeks and a complete re-build ever other year.

It might make sense in you are "off the grid" but ...

[Alan Sung]

Some utlities charge less if you have electric heat. Nstar in Massachusetts charges 13.358 cents per KWH for regular residential service, but 11.344 cents per KWH if you use electric heating (there are slight variations depending upon what town/city you live in).

-al sung

[Clark W. Griswold, Jr.]

Actually, there is a new version of heat pump that works quite well in very cold climates. I was able to look at one installed in North Dakota last summer.

The traditional air vented pumps do not. The newer geothermal heatpumps use multiple wells with a closed circulating coolant running 100-200 feet underground. The temps there are around 55 degrees year round, which is optimum for a heat pump in summer or winter.

Don't know how the capital (installation) costs compare though...

[Charles Spitzer]

[John Gilmer]

That's hardly "new." Just about every variant in ground source heat pumps has been established for years.

Some 6 years ago I was very interested in ground source and other heat pumps. (My HVAC guy basically said, "forget it" but it was fun looking.)

Anyway, one interesting design for VERY cold climates which was marketed in Finland used what they called a "Cold Finger." The outside evaporator presented a vertical "finger" with smooth flutes. In operation, it would ice up (just like any heat pump in cold weather) but because of the shape the ice would just flake off. No outside fan, no (or little) defrosting. And it would look "cool" standing out in your back yard!

[John Gilmer]

Thanks for the link. I "scanned" it and it was a fun read.

[Box134]

Ooooh-eeee! Need an asbestos suit to read your posts.

You're right. I did a calculation to compare the two here in Manitoba. For

730.337 M3 of gas consumption, I'd need to replace it with 7,646 kWh of electricity, considering that both would provide 27,526 Mj of energy.

At those rates electricity would cost $509.50, gas $218.27. Now that's calculated on the efficiency of my furnace. A more efficient one would lower the cost of gas still more, but not by much.

[Rick]

Well here in Canada (Vancouver) we pay 6 cents/KWH which IS cheaper than gas at $11/GJ (approx 10 therms). I zone heat with electricity and my heating bill is $200/year vs $1200 for gas.

[Edwin Pawlowski]

Can I run an extension cord to your house? I'll pay for your use as well as mine. Converted to USD I'm paying triple that in CT. I heat with oil ($1.599) as the only gas available near my house is from eating beans. Ed

[Rick]

Buy a chainsaw and a good woodstove! :)

Thank goodness for cheap hydroelectric power