Does the length of a thermocouple matter? The length of a thermocouple has no effect on its measurement accuracy or its ability to transfer the signal to the instrument.
Are thermocouples universal? Universal Thermocouples. Universal thermocouples, as the name implies work on most water heaters. They are available online and in home supply stores for a reasonable cost.
The length and the thread type are the two concerns when purchasing one. Should a thermocouple be in the flame? Typically the thermocouple sensor is mounted right in the flame of the pilot light on gas fired heating equipment. But not all of these systems use a thermocouple. Some gas fired heating equipment relies on an electronic ignition to ignite the flame.
Those devices generally will not use a thermocouple. Can a thermocouple leak gas? Without a thermocouple, it will seep tiny bits of gas into the combustion chamber of the device. In a few hours, it can leak enough gas for a small explosion, probably just enough to shorten your eyebrows. Can you overheat a thermocouple? If the back end of your thermocouple bulb gets constantly overheated, it will fail. With excessive back pressure coming from the burner ports, thermocouples can get burned up quickly.
How do you replace a thermocouple? Unfasten the three nuts that hold the thermocouple and the two gas tubes to the valve. Detach the thermocouple from the burner. Install the new one the same way that you removed the old one.
Turn the gas back on and follow the lighting instructions on the water heater. These wires are manufactured at the highest tolerances to ensure the fewest possible impurities and the greatest consistency in alloy ratio. Because a thermocouple measures temperature differentials, any temperature fluctuations around the reference junction cold junction , which has the known temperature, result in an erroneous temperature reading.
Solution: Make sure no fans or other sources of cooling or heating are located near the reference junction. Simple insulation can also protect the junctions from extreme temperatures.
A thermocouple should be grounded at only one location. This is likely to generate electromagnetic fields, which can lead to radio-frequency-interference-related problems that can impact measurement accuracy.
Selecting transmitters that have internal isolation between the input, output, and ground usually provides enough isolation to eliminate a ground loop. Loop isolators are also available and can be put in the loop wiring circuit to prevent this from happening. While thermocouples are reliable temperature measurement devices, they do drift with time.
Maximum exposure temperature, cyclic measurements, and frequency of the cycles affect the metallurgy with a resultant drift, usually downward. You can learn more about industrial temperature measurement using versatile and low-maintenance thermocouples from this WIKA reference page. Our website uses cookies. By continuing to use it, you agree to their use.
Further information Agree. Thermocouples from different manufacturers vary as to their dependability. The only thermocouples I recommend are made by Johnson Controls. The K15 and K16 series are the best. If you are having durability problems then use the K16RA, which is a nickel-plated high ambient or corrosive environment thermocouple. The combustion condition excessive temperatures in the chamber is also an issue and this will require a combustion test and draft measurement to insure that excessive temperatures are not being applied to the pilot.
In some cases on water heaters it may be necessary to alter the pilot adaptation to get better quality performance. This however should not be done unless you have had proper training. The possibility of the equipment operating in a depressurization environment will certainly lead to thermocouple failure.
In addition if the equipment is flued together with a "fan assisted" furnace or boiler this can lead to problems. There are solutions to this also but training is required. The thing that I find is often a problem is the environment in which the equipment is operating.
Many times corrosive chemicals and airborne contaminants are being drawn into the air gas mix and a chemical reaction takes place. This again requires attendance at a training session by a professional combustion person to help you to see the various affects this will have. Last of all the failure to put all the doors and covers back in place on equipment.
The failure to do this will cause an alteration in combustion air and the flame stability is affected. The design of some equipment is also a problem. When there is high demand for heat very cold weather the temperatures that are created in the chamber have an adverse affect on the pilot and thermocouple system.
The addition of the K16RA thermocouple can offer some assistance toward extending the life of the thermocouple in this situation. Insufficient air for combustion and dryers operating in close proximity to equipment also lead to problems. Last of all and this is not directed at any one in particular but just plain lack of service personnel and installers knowing what they are doing.
World Plumber Member Posts: November Good tests! We hads a problem years back we were pulling our hair out till Peerless put out a tech bulletin on it. For every degrees above the life of the thermal couple is halved.
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