Testing water tank thermal couple

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guschash

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When testing a water tank thermal couple what meter reading should I expect ? Electric water tank ,lower limit 3300 upper limit 4500. If using my meter and couple is bad if my is 12 ohms is it bad or going bad ,if its good do I GET 3300 OR 4500.
 
guschash said:
When testing a water tank thermal couple what meter reading should I expect ? Electric water tank ,lower limit 3300 upper limit 4500. If using my meter and couple is bad if my is 12 ohms is it bad or going bad ,if its good do I GET 3300 OR 4500.
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Are you talking about thermostat for typical household electric water heater?

Those are a bimetal snap switch type of unit not a thermocouple.

A thermocouple creates a voltage when heated, a common use seen with water heaters is to hold pilot gas valve open as long at there is a pilot flame being sensed on standing pilot type gas water heaters.
 
It sounds as if the 3400 and 4500 refer to the wattages of the upper and lower elements, which will never be on at the same time if the upper thermostat is wired correctly.
The thermostat contact resistance should be a small fraction of an ohm.

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guschash said:
When testing a water tank thermal couple what meter reading should I expect ? Electric water tank ,lower limit 3300 upper limit 4500. If using my meter and couple is bad if my is 12 ohms is it bad or going bad ,if its good do I GET 3300 OR 4500.
Click to expand...
You’re mixed up some where.

Are the elements 3300 watts and 4500 watts? 13.75 amps and 18.75 amps respectively at 240v. 17.5 and 12.8 ohms respectively.

The element that tests at 12 ohms is close, not knowing how good your testing equipment and abilities are.
 
GoldDigger said:
It sounds as if the 3400 and 4500 refer to the wattages of the upper and lower elements, which will never be on at the same time if the upper thermostat is wired correctly.
The thermostat contact resistance should be a small fraction of an ohm.

Sent from my XT1585 using Tapatalk
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Starting to put more together here - 12 ohms is getting somewhat close to resistance of a 3400 watt 240 volt element, I think there is some terminology issues going on. I don't know if the cold vs hot resistance changes much with these elements either, but if he tested something at 12 ohms, my guess is it was likely across an element - and it probably is good.

Add, I don't think 3400 is a common 240 volt rating though, 3800 seems to be a standard rating. 3400 is about what a 4500 watt element will run at if connected to 208 volts though, so what he is seeing as 3400 and 4500 is probably the watt rating at 208 and 240 volts respectively.
 
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