# gas won't stay on ......



## notahvacguy (Jan 23, 2019)

I am working on an Osburn Bay Vista natural gas fireplace insert built in 1995.  I replaced the ITT gas valve with a Robertshaw #710-511 millivolt gas valve and the pilot assembly with a Robertshaw #1819-001 pilot, thermo-couple.  Also installed a new spill switch which was located on the outside of the firebox between it and the masonry fireplace. The pilot assembly, spill switch, wall thermostat, and the on/off switch are connected to the valve on what I think are the correct TH, TP, and TH/TP contacts.  With the glass front off, the pilot light will light and the burner will come on.  When I try to install the glass on the front, the valve shuts all of the gas off.  Remove the glass and everything will work again.  The fan snap/thermo-disc works.  It will turn the fan on and off.  I checked the flexible stainless steel flue for obstructions but found none.  All of the part blow-ups on line do not show or label all of the parts well enough to identify them and the parts lists are incomplete.  What am I missing that could create this problem.  Open to any suggestions.  Thanks.


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## wooduser (Jan 23, 2019)

notahvacguy said:


> With the glass front off, the pilot light will light and the burner will come on. When I try to install the glass on the front, the valve shuts all of the gas off. Remove the glass and everything will work again.







notahvacguy said:


> I am working on an Osburn Bay Vista natural gas fireplace insert built in 1995.  I replaced the ITT gas valve with a Robertshaw #710-511 millivolt gas valve and the pilot assembly with a Robertshaw #1819-001 pilot, thermo-couple.  Also installed a new spill switch which was located on the outside of the firebox between it and the masonry fireplace. The pilot assembly, spill switch, wall thermostat, and the on/off switch are connected to the valve on what I think are the correct TH, TP, and TH/TP contacts.  With the glass front off, the pilot light will light and the burner will come on.  When I try to install the glass on the front, the valve shuts all of the gas off.  Remove the glass and everything will work again.  The fan snap/thermo-disc works.  It will turn the fan on and off.  I checked the flexible stainless steel flue for obstructions but found none.  All of the part blow-ups on line do not show or label all of the parts well enough to identify them and the parts lists are incomplete.  What am I missing that could create this problem.  Open to any suggestions.  Thanks.





https://www.supplyhouse.com/Roberts...IbneY-JWFp5livqzCKNHLomJ9gVQs2Y0aAjBLEALw_wcB

It looks like you have a pilot burner assembly that has BOTH a thermocouple and a pilot generator,  is that correct?


<<With the glass front off, the pilot light will light and the burner will come on.  When I try to install the glass on the front, the valve shuts all of the gas off. 



You need to be more detailed in describing what is happening here.

Carefully observe the pilot flame with the glass off so that the main burner will turn on.  You should observe the pilot flame like a small blowtorch,  with a sharp blue flame that engulfs the thermocouple and the pilot generator.

Now put the glass on and observe and report on any difference in the pilot flame you see with the glass on. What you described is that the gas to the pilot burner shuts off with the gas on.   How long after you put the glass on before that happens?  

If you just put the glass on,  will the pilot keep operating,  or does it shut off withe the glass on but without the main burner being turned on?

Or does the pilot shut off only when you turn on the main burner?

Describe any changes in color or size of the pilot flame.  Carefully observe if the pilot flame pulls away from the thermocouple before the main burner and pilot shut off.

It sounds like the pilot burner and perhaps the whole fireplace is being starved for combustion air.


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## notahvacguy (Jan 25, 2019)

The gas fireplace is in a rental so I could not access it today.  The fireplace front is two piece, i.e., the glass front and a metal louvered top.  When both are installed, they seal against the gaskets enclosing the fire chamber.  The warmed air from the fan blows out of the top through the louvers.  The pilot burner flame is blue.  The tips of the flames only go to the thermopile and the thermocouple but do not engulf them.  I've tried adjusting the gas to the pilot burner but it does not change the flame size.  I assume this is due to the orifice that fits on the end of the 1/8" gas line to the pilot burner.  I had install the gas line without the orifice but the flame was similar to the flame on the main burn when it is lit.  The gas turns off to the pilot burner and the main burner when I try to install just the glass.  This appliance does not use an outside combustion air source but draws the combustion air from inside the house through louvers on the bottom of the unit and openings in the metal plates that the burner sits on.  The pilot light does not go out when the burner lites and does not change color. The gas shuts off almost immediately when the glass is placed on the front but before the metal top piece is installed so there is more than adequate combustion air.  The thermopile goes to the magnet safety valve and I am wondering if the small size of the pilot burner flame is causing the magnet to shut off the gas.  The piezo electrode does not ignite the gas to the pilot burner most of the time but that may also be due to the low volume of gas coming through the orifice that is supplied with the valve.  I don,t know if this gives you enough information to help me.  I am totally unfamiliar with the magnet and  how it operates.


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## wooduser (Jan 25, 2019)

https://www.zoro.com/robertshaw-pil...onKXJRPkGHp1caxg0p8aAoq-EALw_wcB&gclsrc=aw.ds


Is this being used on natural gas or propane?

The pilot assembly you specified comes with a pilot orifices sized for both natural gas and propane.  I'm wondering if you might have installed the propane (smaller)  sized pilot orifice.

In any case,  the problem appears to be that the gas flow to the pilot burner is too small,  not placing adequate heat the keep the magnet energized.

Check to be sure that you have the correct pilot orifice for the fuel you use.  Even a new pilot orifice can be dirty.  I'd replace it again  (you can buy just the correct orifice pretty cheaply)  or at a minimum  take it out and clean it with compressed air.


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## notahvacguy (Jan 29, 2019)

Thanks wooduser for the info.  I didn't see a second orifice.  I will check to see where I can buy one and try it.


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## Heatsource (Jan 29, 2019)

b-vent unit i highly doubt its starving for air, the bottom of the burn tray is open to room air/


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## wooduser (Jan 29, 2019)

notahvacguy said:


> . The pilot light does not go out when the burner lites and does not change color. The gas shuts off almost immediately when the glass is placed on the front but before the metal top piece is installed so there is more than adequate combustion air. The thermopile goes to the magnet safety valve and I am wondering if the small size of the pilot burner flame is causing the magnet to shut off the gas. The piezo electrode does not ignite the gas to the pilot burner most of the time but that may also be due to the low volume of gas coming through the orifice that is supplied with the valve. I don,t know if this gives you enough information to help me. I am totally unfamiliar with the magnet and how it operates.





Well,  now you have me confused.


The pilot assembly I referenced in an earlier post has both a thermocouple and a pilot generator.  Is that what you have,  or is it a thermopile/pilot generator only?


Is this natural gas or propane?  What other appliances do you have on that fuel and have you been experiencing very cold weather since this problem has developed?    In very cold weather with substantial demand,  a propane tank may not be able to absorb enough heat to vaporize liquid propane into a gas,  causing gas pressure to drop.   That could be your problem if you have substantial demand and especially cold weather 

Also,  carefully observe what happens to the pilot when you put the glass on.  With an undersized pilot,  any little change might cause the magnet that is energized by the thermocouple or pilot generator to drop out,  shutting off the gas.   I'd observe that happening several times until you understand what is happening. 

It sounds like you don't have adequate gas pressure or perhaps a dirty or improperly sized pilot orifice.  That's still more of a guess than a diagnosis,  though.


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## wooduser (Jan 29, 2019)

wooduser said:


> https://www.supplyhouse.com/Roberts...IbneY-JWFp5livqzCKNHLomJ9gVQs2Y0aAjBLEALw_wcB
> 
> It looks like you have a pilot burner assembly that has BOTH a thermocouple and a pilot generator, is that correct?
> 
> ...





I keep asking questions to which I don't get a reply.


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## notahvacguy (Jan 31, 2019)

I contacted the company that I bought the pilot assembly from to get a natural gas orifice for it but the can't send just the orifice.  They will send me a replacement pilot assembly.  I will switch out the orifices when I get it to see if it solves my problems.  I will let you know if it does after I try it.  Thanks everybody for the help.


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## wooduser (Jan 31, 2019)

Good luck....


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## Brokenstone (Feb 6, 2019)

I had a similar problem once with a direct vent gas wall furnace. It took me a while to figure out that the pilot orifice was clogged with mineral buildup and the pilot wasn't burning big enough to generate current in the thermopile.


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## wooduser (Feb 6, 2019)

Brokenstone said:


> I had a similar problem once with a direct vent gas wall furnace. It took me a while to figure out that the pilot orifice was clogged with mineral buildup and the pilot wasn't burning big enough to generate current in the thermopile.



A dirty pilot orifice is certainly the most common problem.  It's relatively easy to disassemble the pilot burner and clean the pilot orifice,  although some,  notably Robertshaw bell shaped pilot orifice,  often can't be cleaned and need to be replaced.

However,  since the pilot orifice had been replaced,  it was quite possible it was replaced with a propane orifice,  which would be too small to operate a pilot fired with natural gas.


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