# What's the proper pilot adjustment for VS8420E 2020 Honeywell LP Gas Valve



## tom w (Feb 19, 2019)

I recently replaced the pilot assembly, and about 4 years ago I'd replaced this valve.  Never adjusted the pilot because I thought it was strong and OK.  But now I'm wondering if it's too strong?

I saw a lot of soot on the old thermopile when I replaced the assembly.  Now everything works well, strong blue pilot flame, but I'm wondering if my pilot is too strong, possibly causing the soot issue?  The thermopile is what I'd call "cherry red".  Is that burning too hot and should I therefore reduce the pilot?

There's a slotted, small brass screw to the left of the Off/Pilot/Gas knob, which I surmise to be the pilot adjustment, based on an old Honeywell manual.  (I know there's usually a screw on the outside as a "cap", but mine doesn't have that.  But I can see the threads on the end of the hole where that would go.)  However, when I go to turn the screw, it's extremely tight or stuck...it doesn't budge with moderate force, either way.  Didn't want to break it so I though I'd post.

There's another similar screw that looks to be an adjsutment screw, but that's above the gas Hi-Lo control, and I'm guessing that's for the main burner... which burns fine.

So...
1.  Is my pilot too strong... should I adjust so it's more a dull red, while pilot still burning steadily?
2.  Am I working on the correct screw to adjust pilot?
3.  Why the heck won't it turn... and what's my next step?

Thanks!


----------



## wooduser (Feb 19, 2019)

Yes,  there is one screw to adjust the gas to the pilot and another to adjust the gas to the main burner.  Both should be under cap screws. to protect them and prevent gas from leaking,  and discourage tampering by untrained people.  What you are experiencing is why such adjustments are discouraged!

The screw to adjust the pilot gas is a needle valve.  By turning the screw clockwise you advance the screw and it should gradually plug up the flow of gas to the pilot burner.  Turn the screw far enough counter clockwise and it probably allows the screw to be removed altogether,  although I've never had occasion to do that.

So a jammed screw such as you describe suggests that the screw has been over tightened clockwise,  causing the jam.  But that should have shut the gas off to the pilot. Instead,  you have much too much gas flow.

So it seems like the pilot screw is damaged in some way,  so that it wont turn down the gas the way it should,  even when jammed in past the maximum it should be turned.

You probably should call a fireplace repairman to inspect what you have,  and I wouldn't be surprised that the valve will need to be replaced because of the damage to the pilot adjustment.

If you want to take a chance on DIY repairs,  I'd start by shutting off the gas to the fireplace.

Use a screwdriver that does a GOOD job of fitting the pilot adjustment screw.  I'm betting you will find the screw well down in the hole,  at its maximum advance into the threads.

You can try turning the screw counterclockwise to extract and inspect the screw for damage.  Once it's no longer jammed at the bottom of its travel,  it will probably turn counterclockwise normally.  I'm guessing you will see some visible damage if you remove and inspect the pilot adjustment screw,  but since you wont be able to get a replacement replacing the gas valve would be your solution.

All this is based on a lot of guessing and supposing though.

The bottom line is that you are CORRECT that the gas flow to the pilot is excessive.  The question is,  what can you do about it when the pilot adjustment seems to be bad.


Someone else has very likely discovered this before you,  and tried to turn the pilot gas down,  jamming the pilot adjustment screw into the condition you find it.  That's my guess,  anyway.


Incidentally,  were the two screws covered by cap screws that had to be removed to uncover the brass adjustment screws?  If one or both were missing,  that's a clear indication that someone was working on the valve who didn't leave it in an acceptable condition by replacing the cap screws.

Depending on what you find if your remove the screw,  you might be able to repair the damage by filing the brass screw with a file.  But I'm just guessing with that possible suggestion.


----------



## Millbilly (Feb 20, 2019)

Are you on propane or natural gas


----------



## Millbilly (Feb 20, 2019)

Just read the title and answered my question.  Did you indeed replace the pilot assembly with and LPG pilot assembly?


----------



## tom w (Mar 4, 2019)

Millbilly said:


> Just read the title and answered my question.  Did you indeed replace the pilot assembly with and LPG pilot assembly?


Yes, it's LP.  Thanks


----------



## tom w (Mar 4, 2019)

wooduser said:


> Yes,  there is one screw to adjust the gas to the pilot and another to adjust the gas to the main burner.  Both should be under cap screws. to protect them and prevent gas from leaking,  and discourage tampering by untrained people.  What you are experiencing is why such adjustments are discouraged!
> 
> The screw to adjust the pilot gas is a needle valve.  By turning the screw clockwise you advance the screw and it should gradually plug up the flow of gas to the pilot burner.  Turn the screw far enough counter clockwise and it probably allows the screw to be removed altogether,  although I've never had occasion to do that.
> 
> ...


----------



## tom w (Mar 4, 2019)

wooduser said:


> You can try turning the screw counterclockwise to extract and inspect the screw for damage.  Once it's no longer jammed at the bottom of its travel,  it will probably turn counterclockwise normally.


Sorry for the delay, got busy with a bunch of more pressing concerns.  Thanks... now that I know it's a needle valve and should unscrew all the way I'll try that.  The valve was replaced about 4 years ago with a new one, but it had no cap screws, and no one fooled with it.  Unless it came from the factory damaged.  Thanks!


----------



## wooduser (Mar 4, 2019)

I looked up that part in more detail.  It looks like they never had cap screws hiding the gas pressure screws.

If it came from the factory,  perhaps I'm wrong about the screw being jammed all the way in  ----  is the top of the screw near the surface of the part,  or way down inside the hole?  Now I'm guessing that the screw might be corroded in place?  If that were the case,  there might be no need to remove the needle valve once you freed it up by turning it  ----perhaps with a little bit of oil to help dissolve corrosion?

If it were indeed corroded in place and you freed it up,  it might be simple to screw it down and reduce the gas flow to the pilot to a correct level.   Or with enough corrosion,  you might have to remove the needle valve and clean it of corrosion,

I'm guessing here,  of course.

Pictures of the valve and it's condition might be a help....


----------



## tom w (Mar 5, 2019)

Thanks for your reply, I really appreciate it.  The screw is pretty far down in the hole.  I attached a couple pictures, first is just from the web, 2nd is my actual valve when I had the stove apart.  Valve itself isn't corroded on the exterior, it's only 4 years old.  However, of course it's quite possible it's got some corrosion inside... LP can definitely have moisture issues, and humidity is pretty high in the summer.  
Yeah, maybe I'll give a little shot of PB Blaster or liquid wrench, and tap it a little. 

It's been pretty cold here in Upstate NY, I think I may wait until April to try anything more than that... if it breaks now I'll be out of commission for a while.  I'll report back when I try the penetrating oil.  Thanks!


----------



## wooduser (Mar 5, 2019)

I've never encountered this kind of issue with a screw in a valve like that.  The comments I've made are ideas on what might be happening,  but  not based on real experience.  So your guess is as good as mine.

My guess is that you should be able to free up that screw with some effort and penetrating oil.  Best bet would be to start turning it counterclockwise,  in case it might be turned all the way down.  

Good luck!  I'd be glad to hear how you manage with that when you work on it some more.

Sorry I can't offer you more,  but no point in making too many guesses  ----you can see some of what I thought has already been contradicted by additional facts that have come out so far.


----------



## tom w (Mar 5, 2019)

Thanks for your help, I'll definitely report back when I get a chance to try it.


----------



## bkaul (Oct 8, 2022)

I know this is an old thread, but in case anyone finds it in a Google search like I did, the brass screws being targeted above are pressure taps to hook up a manometer for troubleshooting, not the pilot adjustments. You do *NOT* want to remove these thinking they're adjusting valves. If you look closely, there is a cap screw on the corner near the wiring connections that's labeled "PILOT ADJ" - that should be where the pilot adjusting valve is located.


----------



## Tech Guru (Oct 17, 2022)

Yeah, if he budges the screw he targeted in that picture, he's going to open the inlet pressure test point.  Putting LP into the home.

Pilot adjustment cap screw is at the bottom right corner of his front on picture.  Top left in the actual picture of his control...


----------



## RXH (Oct 31, 2022)

Hello, Came across this site and think it can be helpful to me. I just replaced a Pilot Burner assembly on a 30 year old Crown Aruba natural gas furnace. Put it all together and ignited the pilot flame. However, I know the assembly is new and the flame is crisp but I'm thinking the pilot flame might be too high. So, I'm wanting to adjust the flame and want to confirm if the image I posted with the red circle around it is the pilot adjustment. If anyone know, I would appreciate very much your response. Thank you


----------



## RXH (Oct 31, 2022)

RXH said:


> Hello, Came across this site and think it can be helpful to me. I just replaced a Pilot Burner assembly on a 30 year old Crown Aruba natural gas furnace. Put it all together and ignited the pilot flame. However, I know the assembly is new and the flame is crisp but I'm thinking the pilot flame might be too high. So, I'm wanting to adjust the flame and want to confirm if the image I posted with the red circle around it is the pilot adjustment. If anyone know, I would appreciate very much your response. Thank you
> 
> View attachment 301779


Well I just did find the documentation and that is indeed the pilot adjustment screw. it turns easily clockwise BUT the pilot flame doesn't decrease. any thoughts?


----------



## RXH (Oct 31, 2022)

RXH said:


> Well I just did find the documentation and that is indeed the pilot adjustment screw. it turns easily clockwise BUT the pilot flame doesn't decrease. any thoughts?


UPDATE: In case anyone else comes across this issue (which really isn't an issue).. Keep turning the screw. Eventually, the flame will drop. must be a long screw. Case closed.


----------

