[pfgallo]

Hi, I have a Magic Chef Furnace with a Robertshaw Ignition Module and White Rogers Gas valve. The problem is that the gas valve will not open to start to flame to the furnace. If you turn up thermostat, I then get spark and then a pilot light. Then nothing. I have replaced the Ignition Module and then replaced the gas valve and still the same. I could have another bad Ignition Module and or Gas Valve. I need to know how to test the gas valve to see if it is there. I do see voltage changes from the Ignition module so leads me to the gas valve still. The gas valve is two stage module. I am a Electrical and Mechanical Tech so working on this is no problem, but cannot find any information to test this out, Any information will be appreicated. Thanks, Paul

[leoacrh]

Check your gas pressure at the valve

[pfgallo]

Hi, Do you know what the gas pressure should be?

[hvac1000]

Gas valve model number?

[leoacrh]

It should be on the valve

[pfgallo]

White Rogers 36C76-402

[leoacrh]

Look on the side of the valve or if you still have the box read the specs on the box

[pfgallo]

Hi, I am talking to the local gas company to come out and test the gas pressure. They cannot tell me what they normally supply. In the mean time if some one know how to test the valve.

[leoacrh]

Do you have a multimeter

[leoacrh]

If so hook it to the terminals on the vavle turn on the heat and read the voltage should be at least 24 volts

[pfgallo]

Hi I am way past that measuring the voltage 24 VAC, need to know how to test the actual valve in my hand. The voltage looks to be there to tell valve to opbe but gas valve does not open.

[leoacrh]

Run 24volts to valve and blow air through valve to see if it opens

[KISS]

The pilot flame has to be detected in order for the main valve to open. Likely 24 VAC won't do it. Need a link to the gas valve model #.

Proven can be done with a capilary tube or by rectification by the flame.

At this point, it's probably a flame sensor issue.

[hvac1000]

36C76-402 Bad number. Never produced by White Rodgers/not contained on White Rodgers master list.

Please recheck the number and repost.

NOTE since you replaced the valve and module please post the old part numbers also to see if I can locate a cross for those parts also. Also post the Magic Chef model number for the furnace. Thank you

[pfgallo]

Hi, Sorry for incorrect number -it is 36C76-224 which if you go to White Rogers website it does not give a replacement. Using 36C76-407 as a replacement. The ignition module is a one to one exact replacement. Could the 24 V transformer be bad and not able to send enough Amperage to the gas valve to open? Really do not think its this, grasping at straws now. I have the gas company coming Monday to check the incoming pressure. Furnace number need to get tomorrow. If the gas pressure turns out OK, still need to test gas valve some how.

[hvac1000]

Actually I believe you are in over your head on this one

You say you have a Robert Shaw Ign mod. That was the first mistake. Get the correct W/R part or start over. Many times it is posted that a Robert Shaw mod will work and they will not with a W/R valve.

NOTE: the pilot flame has to be proven by a signal back to the module to allow the main burner to be turned on. You might have a problem with the flame sensor (clean it) or replace if the signal is to low. You will need to go to the R/S site to get the needed signal value for the module you are using. Check all grounding also. These systems need the components grounded and the 120 volt circuit needs a good ground all the way back to the panel.

[pfgallo]

Hi, Do not understand what the mistake is?

I work for a large compressor company and was a serviceman for 15 years traveling all over the world (when on the road I was the best they had and traveled to the worst jobsites) . I work on Million dollar equipment, that includes Compressors PLC controls, High voltage up to 6000 volts, medium voltage, low voltage, Switch gears, MCC contactors, can work down and trouble shoot to PC board level, work with Lube oil systems, Tuning gas control systems, work with pressure of up to 600 psi with all kinds of gases that need to be compressed.

So this is really no big deal to work on, the problem is I do not have Literature to read of how the gas valve works and or the module works. If I have that then I could trouble shoot this system better. If I call someone here they are usually parts changers and just change the parts till it works. I have 15 years controls experience and would not be here if I had the information to read or test procedures.

This Magic Chef Furnace came new with the Robert Shaw module, and W/R gas valve. The module has been replaced a few times over the years and would work fine again as well as flame sensor has been changed before. This time the module was replaced and the gas valve still did not open. The flame sensor was remove and cleaned till bright metal was seen too.

If you raise the thermostat over the room temperature, the module starts to spark as soon as the pilot lights the spark turns off, if you disconnect the flame sensor it starts to spark again, so it is seeing the flame. Then as I said before nothing, no gas valve opening. When this started I measured the voltage at the gas valve and it looks to be were it should when needed and off when not. So that lead me to the gas valve as a issue. So got another gas valve. The new one has the exact electrical connections as the old one and looks the same. The Hi and low pressures are slightly different but this should not stop the valve from opening.

One person said to measure the incoming gas pressure, this I did not know that these need a Min pressure to open or that's what they are implying.

The gas company is coming tomorrow to check there pressure . I will install a new ground wire to the system as suggested and double check that it is good.

Any other ideas would help and or if someone knows how to really test a gas valve if it is good, like resistance readings across terminals or what other electrical tests can be made to it. Thanks, Paul

[hvac1000]

So this is really no big deal to work on

Yes it is because of this

I do not have Literature to read of how the gas valve works and or the module works

NOTE:
Magic Chef/Armstrong corporation never did mix manufactures of equipment. They used W/R or Robert Shaw but never mixed. My small company did the paint line changeover at the factory in Ohio in the 70's during one of the other energy problems we were in at the time. Multi burner's for natural gas,L.P. gas and # 2 oil were installed by us including all the pipe and electric. We had fun back then with our own version of design build. LOL

Naturally with a good factory connection we sold some of there equipment for lite commercial/small bis jobs and never did I run into a combination of W/R and Robert Shaw controls/valves. The liability issue is just too much to risk. Now in the replacement arena that is a different story.

Se if there is a diagram on the blower door of your unit.

WHAT is the model number of the furnace? I have some old books that might contain info but without the number you know the drill.

[KERNAL]

Is thr GV in the "on" position?

[KERNAL]

I have seen GV's with the wrong knob - so off is on - also if the knob spins, it is brke & not turning the vavle stem.