Water heater acting strange. I think


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Old 02-03-10, 11:25 PM
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Water heater acting strange. I think

My 7 year old Bradford-White 40 gal water heater is acting up I think. I did a water temp measurement at the faucet and it read 120 deg. I turned it up a notch and it read 160 deg. This is not right because the manual says that the next notch is 160. I turned it back down to the original notch and it reads 137 deg now. I am trying to get 140. Not sure if this makes any difference but the temp control feels loose on the side. I also notice that in the morning some days I have enough hot water for two showers and some days I don't. On the days I don't I need to gradually turn up the hot side more and more. What could this be? Much help appreciated.
 
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Old 02-04-10, 01:06 PM
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Update - Happened again today

I took a shower this morning and noticed the water was cooler than usual. The only thing I can relate this to is my furnace running or not. When the air in the home is 68 or 70 deg The water heater seems to work fine. When the furnace is off at night and it reaches 60-62deg then in the morning the hot water is cooler.

Do hot water heater t-stats interact in some way with the ambient air temperature and could this mean my t-stat on the water heater is bad?
 
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Old 02-05-10, 12:53 AM
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Is this an electric or gas water heater?

No, the thermostats on water heaters are not affected by ambient temperature but the lower the temperature at the tank the faster it will lose heat to the surrounding air. This may be more prevalent with a gas-fired water heater.

The thermostats on water heaters, both gas and electric, are not precise instruments and any markings on them are what would be called "reference only" back when I was working for a living. Also, the thermostats have what is known as a "dead band" which is the temperature range between when they shut off and they start up again. Commonly on water heaters this dead band is about 20 degrees.
 
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Old 02-05-10, 06:13 PM
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Originally Posted by furd
Is this an electric or gas water heater?

No, the thermostats on water heaters are not affected by ambient temperature but the lower the temperature at the tank the faster it will lose heat to the surrounding air. This may be more prevalent with a gas-fired water heater.

The thermostats on water heaters, both gas and electric, are not precise instruments and any markings on them are what would be called "reference only" back when I was working for a living. Also, the thermostats have what is known as a "dead band" which is the temperature range between when they shut off and they start up again. Commonly on water heaters this dead band is about 20 degrees.
20 degrees? I read something about that. This is unacceptable in my book! That's the difference between your dishwasher working properly at 140 and not working at 120 deg according to the manual. I am going to need a narrow deadband if i get a new one. Thanks for the info.
 
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Old 02-05-10, 07:14 PM
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I seriously doubt that you will find a thermostat for a water heater, either electric or gas (which, by the way, you did not answer), that has a tighter deadband. The truth is that the hot water is taken from the top of the tank and that temperature does not vary as much unless you regularly use more than 70 % of the heater's gallon capacity in a short period of time.

The thermostat needs that deadband (sometimes called differential) to keep from activating the burner (gas) or electrical element in a rapid on-off cycle.

You could, of course, engineer your own thermostat that would have a deadband as close as 0.01 degrees but it would void the warranty (if any) on the heater and if anything happened to cause your heater to catch fire or worse it is highly probably that your insurance company won't even acknowledge you having a policy.
 
 

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