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What does MV stand for on a gas valve?
These are usually a PV (pilot valve), an MV (main valve), and a COMMON wire. In the redundant valve one coil allows gas into the onboard regulator where you can set the output pressure and the second coil allows the output of that regulated gas to the burner manifold. Both have to open for the valve to allow gas out.
How does a two stage gas valve work?
How It Works. The two stage gas valve is rather intelligent, switching between modes as needed, based on the thermostat. If a two stage gas valve, which starts at the low-fire setting, finds that your house is not heating quickly, it will quickly switch to full capacity to compensate.
How do you light a gas valve?
Place the lit match or ignited lighter tip at the pilot while depressing and holding the reset button or depressing the knob, as appropriate. Depress the button or knob for about 30 seconds. This maintains gas flow to the pilot until the thermocouple gets hot enough to open the main gas valve.
How do I know if my gas valve is open?
Gas shutoff valves When the long side of the nub or handle is parallel to the incoming gas line, it’s open and the gas is flowing. When it’s turned a quarter turn, perpendicular to the incoming pipe, it’s closed.
What’s the difference between th and TR gas valve terminals?
TH – The 24v hot leg from the thermostat on a call for heat (R+W closing) to the gas valve (TH terminal) to open the solenoid to allow gas to flow. This is assuming that the transformer is good and the high limit is closed. TR – The 24v common/return side of the transformer.
How is the common connected to the gas valve?
The common is connected to the C on the thermostat and the TR on the gas valve. The 24VAC is connected to the (optional TH-TR and on to the) R on the thermostat. At this point, the thermostat has 24VAC power and a C (common) that completes the circuit from the transformer so it will stay powered on, as long as the transformer is on.
What does it mean when a valve is normally closed?
Normally closed (N.C.) means that when the solenoid valve is not energised the supply pressure port is closed off. In the case of 3 way valves the downstream port is open to the exhaust port.
What’s the name of the port on a valve?
L-port – commonly used as a flow diverter. In one position port C is connected to port A, in the second position port C is connected to port B. T-port – commonly used as a valve for draining or relieving the downstream pressure.