bristolflyer
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Question For All You Physicists/engineers

Sun Jan 14, 2007 1:39 am

Good people of a.netland,

I was trying to be efficient recently by using my small table-top oven to heat some food up instead of my industrial-size gas oven. Then it dawned on me - does my gas oven cost me anything to run in the winter?

My heating is thermostatically controlled so any heat produced by the oven will escape into the house eventually and the house heating won't have to come on. The house is well insulated and I'm not opening windows/using the extraction hood when the oven is on. I can't see that the oven costs me anything to run as any cost to run it is offset by a saving on the house heating.

Any thoughts?
Fortune favours the brave
 
YWG
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:44 am

Quoting BristolFlyer (Thread starter):
Then it dawned on me - does my gas oven cost me anything to run in the winter?

Depending on its efficiency, no! Taking into consideration the fact that you are well insulated, the heat transfer coefficient (r) should be low enough to keep all that heat in until it disperses around your house.
Contact Winnipeg center now on 134.4, good day.
 
OlegShv
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:45 am

This would depend on the heating source of your house, meaning wether it's gas or something else and of course the rates from your energy suplier.
 
ANITIX87
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:47 am

Quoting BristolFlyer (Thread starter):
Then it dawned on me - does my gas oven cost me anything to run in the winter?

I probably wouldn't recommend running a gas oven to heat your house. If you light a candle or produce a spark by mistake (static electricity?) you might blow your house. I don't know how flammable the gas is, but it seems to me like even inhaling the stuff would not be a smart thing to do.

TIS
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Klaus
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:50 am

In case of a gas stove you'll probably lose some heat through the necessary exhaust via the chimney so you won't suffocate (even if the additional ventilator isn't on). Unless you've got a heat exchanger there, some of the heat will still escape, but some will in fact contribute to room heating (as will any electrical stove, just at lower overall efficiency and higher cost).
 
Klaus
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:55 am

Quoting ANITIX87 (Reply 3):
I probably wouldn't recommend running a gas oven to heat your house. If you light a candle or produce a spark by mistake (static electricity?) you might blow your house. I don't know how flammable the gas is, but it seems to me like even inhaling the stuff would not be a smart thing to do.

A modern gas stove automatically shuts off the gas supply when the burner should be extinguished, so the risk is actually minimal as long as the installation is intact.

And nobody is proposing to heat the house primarily that way - the point was just whether or not cooking with a gas stove lowered the consumption of the main heating burner - and that it does, even if it's certainly not a replacement.
 
jamesbuk
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 1:58 am

Have you thought about the fact that the gas would give off unpure air? and well you might poisen yourself.

Rgds --James--

P.s. this is pure logic, im not backing it up with any theory.
You cant have your cake and eat it... What the hells the point in having it then!!!
 
David L
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 2:05 am

Some of the energy is used up by the chemical changes in the food as it cooks and doesn't contribute to the heat. Just don't ask me how much!

Quoting ANITIX87 (Reply 3):
I probably wouldn't recommend running a gas oven to heat your house. If you light a candle or produce a spark by mistake (static electricity?) you might blow your house. I don't know how flammable the gas is, but it seems to me like even inhaling the stuff would not be a smart thing to do.

But the gas would already be burning.  Smile
 
comorin
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 4:35 am

I think the only real issue here would be the by-products of combustion. If there is an accumulation of unburnt gas, CO or other noxious substances overnight you might wake up in a place far, far away.
 
David L
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 5:23 am

Why don't fears about combustion products and unburned gas apply to gas central heating too? I suspect effeciency is the major problem with using an oven to heat your house.
 
comorin
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 7:18 am

Quoting David L (Reply 9):
Why don't fears about combustion products and unburned gas apply to gas central heating too? I suspect effeciency is the major problem with using an oven to heat your house.


Gas Central Heating uses gas to heat water in a boiler (heat exchange). The hot water is piped around the house to radiators. The flue (combustion) gases escape into the outside air. Gas Central Heating systems are designed for unattended 24-hr operation, gas ranges are not. In NYC, many fires in winter are caused by the misuse of gas ranges.

But I could be wrong  Smile
 
YWG
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 8:28 am

Quoting Comorin (Reply 10):
Gas Central Heating systems are designed for unattended 24-hr operation,

Not so much. They're pretty old technology and extremely inefficient when compared to modern heating systems.
Contact Winnipeg center now on 134.4, good day.
 
bristolflyer
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 8:40 am

Thanks for the replies. For the record, I use the same gas source for my heating as for my oven.

Quoting Klaus (Reply 4):
In case of a gas stove you'll probably lose some heat through the necessary exhaust via the chimney so you won't suffocate (even if the additional ventilator isn't on).

What exhaust? When I installed the oven there was a gas feed to it and an electric supply to it (for the clock/igniter). No 'exhaust'.
Fortune favours the brave
 
TSV
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 8:42 am

"Physicists/engineers"

You do know of course that Physicists can't actually do anything without Engineers but Engineers can do without Physicists!
"I told you I was ill ..." Spike Milligan
 
jamesbuk
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 8:43 am

Quoting BristolFlyer (Reply 12):

The extractor, the bit that gets rid of the fumes that are going to be coming from that flame. As the fire does create a gas, a gas which if unventilated could do god knows what to you.

Rgds --James--
You cant have your cake and eat it... What the hells the point in having it then!!!
 
David L
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 9:31 am

Quoting Comorin (Reply 10):
The flue (combustion) gases escape into the outside air. Gas Central Heating systems are designed for unattended 24-hr operation, gas ranges are not.

That's true but gas ovens are often operated for several hours, when cooking a large turkey, for example, and I'm not sure my central heating boiler ever operates for more than half an hour before the thermostat cuts in.

What about portable gas heaters for use indoors?  Smile

Out of interest, what exactly is the product of burning natural gas in a correctly working oven? I guess that's one for the chemists.  Smile
 
bristolflyer
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 9:49 am

Quoting Jamesbuk (Reply 14):
The extractor, the bit that gets rid of the fumes that are going to be coming from that flame. As the fire does create a gas, a gas which if unventilated could do god knows what to you.

Other than the extractor hood above the oven there is no 'exhaust' system for the oven. So the gas that the fire creates disperses within the building.
Fortune favours the brave
 
adh214
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 9:50 am

A gas oven produces CO2 when in normal operation. In the quantities that a gas oven produces while cooking this does not need to be vented. (ina domestic setting)

However, if you oven is not working correctly, it will produce CO or carbon monoxide. This is dangerous and can kill you. A good friend of mine's heater was repaired recently and all of the sudden he was much more energetic after the repair. I think his heater was poisoning him with carbon monoxide (not enough to kill him but enough to make him lethargic). Thus, keep your gas appliances in good repair.

You are correct a gas oven basically cost nothing to run during the winter as you are either going to burn the gas in the oven or in the furnace. One posted correctly pointed out that some energy is lost in the process of actually cooking the food. Additionally, some heat is lost in the process of heating a piece of meat from 32 degrees F to 160 degrees F. This assumes that the meat was refrigerated before you started cooking it.

Personally, I do a great deal more baking and roasting in the winter because it heats up the house generally. In the summer, I try to grill to take the heat outside. Unfortunately, my oven is electric so I am using expensive electricity (12.5 cents US per kilo watt) to save relatively inexpensive gas.

Finally, to save energy it is not a good idea to place hot items in the refrigerator immediately. Of course this has to be balanced with health concerns of leaving them out. For example, if you make a soup let it cool covered on the stove for an hour before placing it in the refrigerator but don't leave it out for more than 2 or 3 hours or you could have food poisoning.


Andrew
 
allstarflyer
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RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 11:11 am

Quoting BristolFlyer (Thread starter):
Then it dawned on me - does my gas oven cost me anything to run in the winter?

Have you considered running an electric space heater? You'd only have to focus on the specific areas where you would need heat (sleeping, dining, lounging, etc.).

-R
Living the American Dream
 
David L
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Joined: Tue May 18, 1999 2:26 am

RE: Question For All You Physicists/engineers

Sun Jan 14, 2007 8:14 pm

Quoting Adh214 (Reply 17):
A gas oven produces CO2 when in normal operation. In the quantities that a gas oven produces while cooking this does not need to be vented. (ina domestic setting)

However, if you oven is not working correctly, it will produce CO or carbon monoxide.

Exactly as I suspected - thanks! So a properly functioning gas oven does not produce toxic fumes and a simple CO detector would let you know when there's a problem.

Quoting Adh214 (Reply 17):
Additionally, some heat is lost in the process of heating a piece of meat from 32 degrees F to 160 degrees F.

I did consider including that but then I thought some of that heat is going to warm you from the inside and the rest will be radiated into the surroundings to heat the air - not "waste" as such.  Smile

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