Pizza oven won’t light

[ectofix]

Verify that the ball valve supplying gas to the oven is -INDEED- fully turned on and the gas hose (if it has one) is fully connected by ensuring the quick disconnect is fully seated.  Otherwise, consult your owners manual for guidance on troubleshooting.  Since you didn’t provide a model number, I can’t provide you one.

 

If none of this solves the problem, then call a service company.  There’s simply too many variables to your situation.  A technician will need to troubleshoot it.

[fixbear]

Unless you own a manometer and know how to use it, Ectofix is right.

[john]

This is the same user who posted Regulator LP gas is not putting out gas 

 

Thanks for joining and welcome to you, samps129!

 

So, either you’ve got two ovens down or you’ve got a regulator not putting out gas to the pizza oven which won’t light, and you’re lighting it manually.

 

Sounds like the regulator (you installed?) isn’t putting enough gas out. Keep in mind, it may not be lawful for you to mess with gas connections in a commercial setting depending on your state law, of which the burden is on you to know.  

 

It’s never something an owner/operator wants to hear, but be safe and choose a qualified tech for the job. Safety first! It’s not worth endangering yourself or your employees. Coupled with the above information re: state law, you can be liable if something bad happens.

 

Plus, your ovens likely aren’t cheap; breaking them will just cost more.

 

I am curious, did the old regulator malfunction? How’d you know? Or perhaps are you working on a conversion?

 

-John

[fixbear]

I was hoping that we could get some feed back on his oven.  Especially model.   I know from experience that different parts get blamed for problems and replaced when they are not at fault.  I would sure like to know how many. More than less would not surprise me.

[ectofix]

John B (Parts Town Admin) wrote:

 

So, either you’ve got two ovens down or you’ve got a regulator not putting out gas to the pizza oven which won’t light, and you’re lighting it manually.

 

Let me clarify something.

 

He should NOT be able to light the main burners manually.  ALL ovens will have some form of a pilot safety valve (PSV).  Be it a TS11 PSV, a BASO PSV, or a combination valve – that valve should NOT allow the main burners to have any gas supplied to it if the pilot isn’t lit.

 

This is a KEY function of a pilot safety system that EVERY technician should check whenever they work on an oven.  It’s called a “lock-out” test.  Ovens are particularly dangerous if lock-out doesn’t occur within a specific time (about a minute) after the pilot burner extinguishes.

 

AGAIN:  Gas SHOULD NOT be allowed to flow into the main burners when there’s no proof of a proper ignition source (the pilot).

 

Additionally, the PSV is designed to cut gas supply to the PILOT burner if its own flame goes out.  That’s also part of the aforementioned lock-out test.

 

SO:  If he’s able to light the main burners MANUALLY…without having to light the pilot while pushing in that button (or knob), then he has a DANGEROUS situation there and needs to have it repaired before ANY attempts to use it again.

[john]

As always, thanks for the in-depth info, ectofix. 

When OP said “light with match,” I was thinking he’s holding it at the pilot to prove flame. Would that even work? It doesn’t sound like it based on your explanation.

 

In that case, if he has to, in fact, “light with match,” have the safeties been bypassed?

[ectofix]

John B (Parts Town Admin) wrote:

 

When OP said “light with match,” I was thinking he’s holding it at the pilot to prove flame. Would that even work?

Regarding your response to the original question?  Your guess was as good as mine as to what he was expressing.  The way samps129 wrote it is very confusing.  I wasn’t sure why he felt the need to mention a match, but figured he was just saying that’s what he lighted the pilot with, but the pilot wouldn’t stay lit.

 

But to answer your question – no, a match doesn’t put out nearly enough heat to prove flame.  Only the pilot should be able to do that.  Now, a propane torch would get hot enough, but once its flame was taken away – if the pilot flame is extremely weak or non-existent, the pilot safety should lock out in a short amount of time.

I DON’T recommend using a torch though.  It can get too hot and damage the thermocouple or thermopile.

 

I mention both, because I don’t know which one samps129‘s oven has in it.  Some older deck ovens used a “now-defunct” hydraulic safety valve.  Since those were removed from the market, oven manufacturers were sending out standard TS11 pilot safety valve conversion kits for field technicians to retrofit those old ovens.  However, (if memory serves) I think Bakers Pride deck ovens use combination valves.

 

I’ll elaborate some on thermocpouples, thermopiles, their differences…and how a pilot safety system works:

 

A thermocouple (or thermopile) generates a DC voltage when a pilot burner’s flame flame impinges upon its tip (called the “hot junction” portion of those).  The thermocouple (or thermopile) wires are connected to a pilot safety valve.

A pilot’s flame must be of a sufficient intensity so that a high enough DC voltage output is produced in order to push adequate electrical current through the pilot safety valve’s electrical coil to make that coil an electromagnet. That current flow directly correlates to the strength of a magnetic field established by the coil. When the magnetic field is strong enough, it can overcome spring tension that’s opposing it.  Otherwise, the spring would merely push the plunger closed again. So once the field is strong enough, it can hold the valve open on its own.  That’s when you can take your finger off the valve’s button.

 

FYI:

A thermocouple is designed to output 30mV peak voltage.  Thermocouples are most commonly found with pilot safety valves that are typical in standard range ovens.  I’ve seen some griddles…and even open-top stoves use them too.  They’re also in some pizza (deck ovens), but most of those ovens generally use a setup employing a thermopile. A thermopile is designed to output 750mV peak voltage.  Thermopiles are used with combination valves.  Combination valves also have an internal pilot safety valve, but also have a main valve to facilitate cycling of gas output to the main burners on and off through the control of a thermostat.  Combination valves are most commonly used in gas fryers.  Some stand-alone convections use them.  Many deck ovens use them.

 

 

The easiest way to recognize the differences between a thermocouple and thermopile is simply through a play in words:

“A thermoPILE is a bunch of thermocouples that are PILED on top of each other”.

 

In a sense, that’s true.  If you compare the two side-by-side, the thermopile is much fatter than a thermocouple.  From an electrical standpoint, the internal parts of a thermopile is just a whole bunch of thermocouples connected in series.  Therefore, its higher voltage is made possible.

 

 

John B (Parts Town Admin) wrote:

 

In that case, if he has to, in fact, “light with match,” have the safeties been bypassed?

That’s highly unlikely.  It’d be REALLY difficult to circumvent the safety aspects a pilot safety valve (PSV) or combination valve.

 

The reason for my earlier speech regarding lighting the main burners manually?  Pilot safety valves can and DO occasionally fail in an open position.  It’s not OFTEN, but they do.  That’s why I harped on about technicians needing to perform a lock-out test when working on ovens, fryers, gas water heaters, gas fire places…or anything else that uses them.

 

Usually a customer doesn’t even know their oven’s PSV is stuck open that way.  As long as the pilot stay lit, they’re cookin’. 

 

But what if the oven’s pilot were to get blown out at some point when the oven is OFF?  If the PSV is fault and stuck open, gas would continue flowing into the burner chamber and up into cooking compartment.  Even the little bit of gas that a pilot burner puts out can build up in a very short time.  If the gas were to find a happenstance ignition source to ignite it – it could BLOW UP the oven!

That’s all the more reason to a tech to test that system at every service call. 

 

I’ve personally seen the results after this had happened.  I was told an employee was transported to the hospital and found out later on that he’d suffered permanent hearing loss in one ear.

 

Here’s an article I just found on the importance of doing a lock-out test…and more:

Troubleshooting the Standing Pilot Safety System

[fixbear]

Like to add here that with this scenario being a bakers pride, if older, could very well be a hydraulic valve.  I still had 8 customers that had them in service.  And nothing can be more frustrating than a bad pilot assembly  that doesn’t provide the correct heat to keep the valve open..  They can be on the verge and work fine,  then the atmospheric pressure changes and no flame. Or the pilot mixture changes from dust.in the air intake. Lastly the pilot flame deflector onto the sensor element (beryllium copper) can become oxidized and non reactive. Then no matter what one does short of pilot replacement, you will never have the necessary heat to keep the mercury hot enough.