Table of Contents
on/off switch. Thermopile Output- MAIN BURNER ON: 110 mv minimum required for system to operate consistently. If lower than 110 mv, conduct valve operating head test.
How many millivolts does it take to keep a gas valve open?
The thermocouple generates about 20-30 millivolts, enough electricity to keep the part of the gas valve that controls gas flow to the pilot assembly open. This is why the pilot stays lit on its own after the initial lighting. This is also why it stops releasing gas if the pilot light goes out.
How many millivolts should a thermopile put out?
A healthy thermopile in an open circuit test will read between 650 to 850 millivolts or somewhere in between. If the open-circuit test reads below 400 millivolts, then the thermopile likely requires service or replacement.
How many millivolts should a thermocouple read?
Thermocouples designed for residential gas appliances, such as fireplaces, water heaters and furnaces, are made for 30 Millivolts. The reading should be between 25 and 30. Anything under or hovering around the 20 millivolts mark means the thermocouple needs to be replaced.
What does millivolt control mean?
A millivolt ignition needs a pilot light lit to work. Follow the manufacturers instructions for how to light the pilot light. Their function is to light the main burner without having a pilot light running. A switch, remote or thermostat can be used with this system.
What is millivolt control on gas logs?
1. Millivolt Gas Valve. This small amount of electricity provides enough of a current to control an electromagnet that pulls the valve open against a spring; if the current isn’t present, the valve will snap shut and turn off the gas.
How many millivolts does a power pile produce?
The normal millivolt output is 25 to 35 millivolts; on some, you may even get up to 35. The other part of this safety pilot system is the electromagnet (power unit).
How many ohms should a thermocouple read?
A thermocouple should exhibit very low resistance. Attach the negative lead to the red wire, and the positive lead to the yellow. In this case, the reading will be about three ohms. Thus we can conclude that this sensor is a thermocouple.
How many ohms should a gas valve read?
Test the coils with an ohmmeter with the wires disconnected (you only need to disconnect one wire on each coil) and you should get around 40-60 Ohms resistance at the two leads of each coil. If the meter reads much lower or much higher then the coil is bad and needs to be replaced.
How many ohms should a gas valve have?
That’s the common terminal so you’ll leave that there and with the other probe touch one of the other terminals and then touch the other terminal. Both readings should be about 216 Ohms.
How does a millivolt thermostat work?
Millivolt Thermostats Unlike low-voltage systems, they do not require a step-down transformer and are not connected to the household wiring system. Instead, they are self-powered by a special thermocouple device called a powerpile or thermopile generator that produces direct current (DC) electricity.
How do you test for millivolts?
How to Measure Millivolts Plug the red probe into the hole marked “V” or “+” on your meter. The hole may be colored red. Plug the black probe into the hole marked “COM” or “-” on your meter. Turn your meter on. Hold the insulated handles of your probes. Read the measurement from the meter dial or the display screen.
How many milliamps does a thermocouple produce?
A single thermocouple (C Type) is used for a standing pilot system and generally produces around 30 millivolts. This voltage is used by the gas valve to keep the pilot valve solenoid internal to the main gas valve open.
How do you test a thermocouple on a furnace?
Remove the thermocouple by unscrewing the copper lead and connection nut (first) and then the bracket nuts. Next, take your meter and set it to ohms. Take the two leads from the meter and touch them—the meter should read zero. Once this check is done, turn the meter back to volts.
What is the difference between millivolt and electronic ignition?
A millivolt system does not require any external power, and operates solely off of the pilot light being lit, whereas an electronic ignition system requires external power, usually a standard electrical outlet.
What is a millivolt switch?
This light switch is specifically designed to control a gas log set that utilizes a millivolt pilot control. This pilot system has a small flame that generates power for the unit’s gas valve to operate. As a result, they do not require outside power to operate and can be used in the event of a power outage.
How many millivolts should a flame sensor have?
When the flame lights, you should read between 0.5 and 10 microamps (μA), depending on the furnace. Readings between 2 and 6 are common.
How do furnace gas valves work?
The furnace gas valve operates by electromagnets. The primary valve — also known as the safety valve — supplies gas to the pilot light. Without adequate heating of the thermocouple or thermopile, the furnace gas valve closes. As a result, this cuts off the supply of gas to the pilot light.
How do you calibrate a thermocouple?
A basic calibration process involves heating water to 30°C in a thermal bath. Next, each of two multimeter leads is attached to the free end (cold junction) of the thermocouple – at this point, the multimeter should register zero microvolts as both ends are at the same temperature.
Should thermocouple be in pilot flame?
The pilot flame should touch the thermocouple at a specific level. If the flame is blue and weak, and barely reaches the thermocouple, it needs to be stronger. If it extends well above the thermocouple, it’s too strong. Install a new thermocouple by screwing it in, heating it up a bit, and then lighting the pilot.
