sunfire commercial stove/oven pilot wont light

[fixbear]

I understand that you probably have a Garland range, but what model would be a big help as they used many different gas control systems..  Is it a standing pilot or intermittent?  Again, model number is all important here.

[duster]

I have the same issue with a SUnfire SDG1 oven. I have replaced the thermocouple and flame sensor rod. When you turn on the oven, I get lots of spark but no gas at the pilot light for the flame sensor. It has been an intermittent problem for some time so I thought it was a weak spark and or flame sensor? Anything I should be checking?

[fixbear]

You have confused me.  The garland SDG’s don’t use a thermocouple. They use a intermittent spark system by Baso.   Here’s how it works.  The controler calls for heat and 24 volts is applied to the ignition module.  The module supplies 24 volts to the first coil by PV and a spark to the pilot.  Once the pilot lights the sensing rod  Conducts a DC current to the module thru the sense terminal and burner ground.  Once the module senses a DC curent it will power the second solenoid to open the main valve. 

Now if the pilot is not lighting, either the valve is not opening or the orifice is plugged or dirty in the pilot.  If the pilot lights and goes out, You probably have a sensing circuit problem.  Usually the burner ground.  You can determine this with a good DVOM in series set to micro amps DC. It should read about 10 microamps.  Early modules had no retrys and a 5 sec delay. You should also check the connectors for the wiring to the valve to make sure they are tight both on the valves and control module.

[olivero]

Duster, this is for you.

Intermittent failure to light or stay light in my eyes can very likely be a gas valve problem.
I have had multiple gas valves that would open sometimes, then not or open once, heat it up and then not reopen when it was time to keep it hot.
So here’s what I would suggest. 
Hook your manometer to the outlet port, see if the gas valve opens, hook your A meter to the wires going to the gas valve and measure the A draw, it’ll be less than 1 most likely. Then check your data sheet on the valve and see what it SHOULD be. If it’s far below the rated A draw, that means the unit is trying to open the gas valve but not managing to open it, in which case it could be an internal flaw in the gas valve.

Then compare, that’s how I busted my kettles that wouldn’t heat, turned out to be fault gas valves from Honeywell, pulled my hair out until I found out about the A draw being different, that solved it.

[fixbear]

Then check your data sheet on the valve and see what it SHOULD be. If it’s far below the rated A draw, that means the unit is trying to open the gas valve but not managing to open it, in which case it could be an internal flaw in the gas valve.

I think you have that reversed. The high draw should be pulling the armature in.  Holding should be less.  But remember to always check the voltage first. They vary together as well as with the load.

[olivero]

Fixbear,

In my experiences, I would be looking at a gas valve going, why won’t it open? I see the 24V volts, stably there and it won’t open, so I replace it and it works. 

Then I found out later you could do A draws, stumbled onto it by accident, figuring there had to be something different somewhere and I measured A draw.

Here’s what I saw,

Valve gets 24V, tries to open, it’s drawing 0.55 A when it should be pulling 0.7A, the moment it went below 0.55A it wouldn’t open, when it was above that, it would. 

That’s what I saw with this particular application but many times with the same model of gas valve.

[fixbear]

You must have been working on Honeywell’s. The higher draw of amps should be when the armature is partially out.  If the armature get’s to far out the coils magnetic power can’t overcome the spring tension because it is beyond the flux field.  However, if the armature separates from the valve seal, the armature will come in and the amps drop,  But the valve may not flow.  That’s were your idea of a manometer on it comes in.  Rarely do you see that with a Baso.  And on quality ovens, the controls and solenoid valves are not in the combustion area. They also often have cooling fans to the electronic area.

[olivero]

Yes, it was Honeywell and I’ve seen it on multiple honeywell valves.

good to know, Honeywell didn’t really have an explanation for their valves failing, they just warrantied them.

[duster]

Same issue again but I have replaced the Flame sensor and pilot and switched the gas valve with one from the lower identical unit that never had a problem. The Lower oven works fine so the valve is not the problem but now the top oven does not fire at all, no pilot gas etc. I have jumpered out the door switch so not that either. Any suggestions. Spark unit when working shows 24v?

[duster]

Also it is intermittent as it worked fine when i switched out the valves yesterday but not this morning? Sunfire SDG1

[fixbear]

Duster,  I’m hearing two different things from you.First you said that it was intermittent.  But in the original post it said the pilot lit and went out.  It was also a range, not a stacked convection.  Two different animals..  Because you say that you checked the door switch.  And that normally means convection fan.  If so, there is a centrifugal switch in the fan motor that disengages the burner circuit 

Read back thru the post’s  If you have spark, and 24 volt at the valve, and the gas is on,  then the controller is sending it into lighting.  Now if the valve is not opening, (you should hear it click) Then you have a valve problem.  If it does supply pressure to the pilot line,  you have a blockage. Either in the line or pilot orifice.

Now the power to the ignition comes from the main board thru a 15 pin connector pin 9 to the door switch and then the ignition module. You should have pilot if you have power to the Baso ignition control at 24neg and 24volt.

You can find a wiring diagram here;  https://www.heritageparts.com/medias/DUK7346.pdf?context=bWFzdGVyfHBkZi1tYW51YWxzfDEwNzU4MDd8YXBwbGljYXRpb24vcGRmfHBkZi1tYW51YWxzL2g4My9oMzAvODk2MjgzMjc2MDg2Mi5wZGZ8MWYyYmM1YTI1ZDliMTIyYmMwYTU4ZThjZGI1ZmYxMDczNGE4NGYwMzE0NDk4ODU5MTgzNTM0NDM4NWM1NjcwMg

[duster]

Sorry it is hard to put everything in an email that makes sense to me. Yes they are stacked gas convection SDG1 ovens. Bottom oven never has had a problem. Top one seemed to have intermittent problems. Light sometimes and other times nothing. After replacing the pilot and flame sensor on the top one, I switched valves from one to the other to see if it was the valve. The Top oven valve went into the bottom oven and the bottom one still runs fine. So I assume that rules out valve issues since the original top oven valve works fine in the bottom oven and the bottom oven valve that never was a problem is now in the top oven which worked fine yesterday but wouldn’t light today? Any suggestions?

[fixbear]

Don’t be afraid to let us know how your doing with this.