Gas Fired Hot Water Heater Safety Question

Hello,
Regarding the typical home (vertical cylindrical type) gas fired hot water heater.
Is it "legal," or a good idea, to shut off the water supply to these units when, e.g., going away on vacation and one would want to shut off the whole house water supply ?
Have had some pinhole water leaks in house Copper piping, and shutting off the house water supply on vacation seems like a good idea.
But, was wondering about the safety for the gas fired water heater.
For the typical reasonably modern, heater, if a leak, somewhere, develops, and the tank, somehow, gets depleted of water, is there some sort of over-temp safety that would shut off the gas supply ?
Any thoughts on this would be appreciated.
BTW: -Probably the furnace would be O.K., as it's forced hot-air. -Just out of curiosity: what legal or safety rules would apply to a forced hot water system; same as for the water heater ?
Thanks, B.
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I'd shut off the main water supply to the house and turn the valve on the water heater to the pilot position. That prevents the whole house from any leak, keeps the heater from being on, and saves gas.
The water heater has a final over temp mechanism in the gas valve on the water heater. If for any reason the temp exceeds a max temp, it cuts off the gas, permanently.
With a hot water heating system, in summer, during extended leaves, you could shut off the water to the house and turn off the boiler. During the winter, at least in the northern parts, you don't have that option.
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You are going to have major plumbing problems if you don't start ASAP getting rid of your copper pipe. For now, if you are going on a trip, treat the house to a full shutdown of all water related fixture, appliances. There are many online articles on best practices with neat ideas like turning down the thermostat on the water heater. In your situation, PEX would be the logical new piping for the house. Pinholes in the copper are telltale sign that the water system is chemically or electrically corrosive.
Joe
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I can agree with this. I spent about 2 years fooling around with copper pipe leaks in a 30 year old house. After spending about half a day fixing one and then another before I got them all fixed, I called the man and had it all replaced with the PEX type.
It is amazing how much water can come out of a small hole in a couple of days if you do not find it when it first starts.
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On 1/26/2011 4:30 PM, Bob wrote:

Simple, if you turn the water off, then turn the water heater to pilot or off.
--
Steve Barker
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It is.

You did remember to turn the burner off or at least on pilot only, right?
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Replace ALL the copper with PEX and end the problem forever.:)
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Read the manual, as different water heaters work differently.
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