If I bypass all safety's with strap main burner lights. I have bypassed each safety one-by-one but this don't help isolate problem. have changed 750 volt thermopile. I have cleaned pilot orfice. I read 629 milivolts from thermopile disconnected from ckt while holding pilot button down to keep pilot on. I read approx 30 ohms resistance thru the safety ckt in series; 2 hi-limits, pressure switch,fuseable link.
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Re: pilot on main burner won't light.
30 ohms is too high. You generally need it close to or below 1. You need to read the ohms across each switch to find the connection or switch that is holding up your control voltage from opening the valve. If that still doesn't work, jump the th terminals on the valve and see if the valve even opens. You may need a new valve.
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Ovens generally have a couple of safety devices fitted meaning no gas gets to the oven unless there is sufficient gas pressure. There is also a valve controlled by a thermocouple. The valve prevents gas passing. There is a bypass operated by either a button or pressing in the oven control knob which allows gas to flow to the pilot light (and sometimes the burners). When the pilot light is lighted and has been burning for about half a minute with the flame correctly set to heat the thermocouple bulb the valve will switch on the gas supply and the knob or button can be released. The burners will initially be at maximum until the oven thermostat reduces the flow to maintain the temperature at a preset level.
If gas isn't reaching the oven and the pipework, oven control and thermostat is ok then the safety thermocouple is either defective or wrongly fitted.
this can be caused by a few different items. it can be a faulty/broken flow sensor, broken pressure switch, bad fireman switch. the best bet is to get a qualified pool heater technician to fix it properly. bypassing any of these safety devices is a bad idea
Depending on the specific unit you have the hot surface igniter (glow stick) may be only for lighting the pilot, which then ignite the main burners. The flame has to be proved before the gas valve opens for the main burners. This is done by the flame rod, which could be faulty in your case. The proximity of the igniter could also prevent ignition. Check that the flame rod is clean and secure. Note. be very careful when servicing gas appliances, and never ever use lighters, matches or any other flame source to light them except for the ignition system supplied by the appliance. These appliances are designed and built with safety devices to prevent ignition when it senses a fault or malfunction. This is all for safety. Do not bypass safety devices, it can kill. Call a qualified tech.
Gas ovens are fitted with at least one safety device and it could be it has failed.
The safety device is bypassed while the pilot light is lit. The pilot light heats a thermocouple bulb which switches the gas on to the burner. As long as the pilot light continues to heat the bulb gas will continue to flow - until the thermocouple fails, they aren't long-lasting...
The pilot light jet may have got a little bit of dirt or grit in it which is preventing it from keeping alight. If the pilot light has only a weak flame, the whoosh of the main burner igniting can quite often blow out the pilot. Try probing the jet with a fine piece of wire to see it the blockage can be dislodged. You may have to unscrew the jet to clear it by blowing air through it. Make sure gas is turned off first before removing any parts.
The pilot light also has a thermocouple that allows gas to the pilot light while the flame is burning. If pilot flame goes out for any reason, it shuts the gas off to the pilot jet to prevent unburned gas collecting and causing a safety hazard. The thermocouple is bypassed by a switch during the initial ignition and once the thermocouple warms up after a minute or two of holding in the bypass switch, it should maintain the pilot. If, after cleaning, the pilot light keeps going out, it would seem that your thermocouple is faulty and needs to be replaced.
I have the same problem with one of my burners (I have a morice range). I changed the thermocouple, but it didn´t help. I contacted Morice in France and was told that the problem most sertainly was the coil inside the gasvalve. I don´t know if it possible to dismantle the ovengasvalve to check the coil. As for a burner valve, one should open the valve at the end were the gas goes out to the burner to locate this coil. Best of luck
Have you checked your pilot generator voltage while everything is connected properly? You may have a shorted wire or limit or even thermostat. If you jump the TH connections on the gas valve, it would lead to shorted, inoperable safety, thermostat.
If everything is connected properly, the MV reading should be 500+, less than this and you are losing power somewhere.
Hello. It sounds like, from what you said, you have a new thermocouple. The device it is attached to, the pilot safety, could have a problem internally that allows gas to the pilot, but does not open the main part of the valve, or electrically has failed on the main coil. If you have a thermostat with wires on it, you can jumper the wires, to bypass it, temporarily please, if it comes on, you need a thermostat, if not, it is the valve most likely.
Hi there, it sounds like your thermopile, for the pilot, is failing during use, when this happens, the small DC voltage it generates is less than the gas valve requires to stay open, and shuts off the pilot, which shuts off the main burners. Another thing that could be happening, is the hi limit is opening prematurely, instead of shutting of the pilot at 450 deg. it now is opening at 325, or 225 or 250. Sometimes the sensing bulb gets broken where it pass's through the oil tank causing this symptom. If you temporarily bypassed the hi limit to test this also, and it still goes off, you need a thermopile. If it stays on, check your temp with a reliable thermometer, and see if it reads fairly close to your setting, if so, then you need a hi limit. Hope that helps, and thank you.