Basic furnace pilot question

[bchee]

This is a pilot for a gas furnace. Can someone please tell me why it is shaped in this split fashion?

One flame heats the thermocouple directly.
The other flame doesn't seem to do anything, just blows off to the side.

Why is this? THANKS

 

[ZeroSignal]

Should be directing the flame towards the burner to light the burners.

 

[MrMark]

One flame to light the burner, one flame directed on the flame sensor, i.e., thermocouple. My honeywell valve only has one pilot nozzle directed to the hot film igniter and the flame sensor. It covers both.

You have an interesting setup.

 

[bchee]

Thanks guys

Can I save a reasonable amount of gas by setting the pilot flame as low as possible?

 

[MrMark]

Thanks guys

Can I save a reasonable amount of gas by setting the pilot flame as low as possible?

It should be as low as needed to accomplish its purpose. There is usually an adjustment and a spec on pilot flame width/length. You will save a little gas by having it correct.

Mine is presently messed up because it is way too big a flame and I can't turn it down for some reason. The pilot adjustment screw doesn't do anything.

 

[ZeroSignal]

You don't want it turned down to low. Just enough flame for the pilot flame to pass over the tip of the thermocouple. To high will burn out your thermocouples. To low and they won't heat up enough to open the gas valve.

 

[ZeroSignal]

It should be as low as needed to accomplish its purpose. There is usually an adjustment and a spec on pilot flame width/length. You will save a little gas by having it correct.

Mine is presently messed up because it is way too big a flame and I can't turn it down for some reason. The pilot adjustment screw doesn't do anything.

what gas valve do you have on your furnace?

 

[bchee]

My pilot adjust screw was actually a screw within a screw. One screw came all the way out, then inside was the actual adjustment screw, with a slot for the a flat head.

 

[MrMark]

what gas valve do you have on your furnace?

Thanks in advance for any help. I am flumoxed by my pilot problem.

Here is the number: SV9500M 2682

Honeywell Valve.

 

[MrMark]

My pilot adjust screw was actually a screw within a screw. One screw came all the way out, then inside was the actual adjustment screw, with a slot for the a flat head.

Same here, but mine doesn't do anything. And, it's very very hard to get at. You need a special length screwdriver. I ended up using an eyeglass screwdriver as my mini snap-on's woudn't fit without grinding the handle. The inducer motor is right in the way. A poor set-up.

 

[ZeroSignal]

Are you sure your adjusting the pilot adjustment screw not the regulator adjustment screw?

 

[MrMark]

I can't see your picture? It has a cap (Phillips screw) that removes to allow access to a small slotted screw in a bore. It is right next to the fitting for the aluminum pilot tube.

There is a larger, easier access, plastic slotted screw on the regulator. I wonder if that is the main regulator adjustment?

 

[Hlidskjalf]

Typically you are looking for the smallest possible pilot to prove your flame and light your main burner. If the thermocouple proves the flame your burner should light within a few seconds of activating the main valve.

If the main burner fails to light within 1-3 seconds you should adjust pressure or thermocouple height.

The fail proof way is to set the pilot pressure to manufacturer spec. and adjust the thermocouple just high enough to prove the flame.

The only real danger is if the pilot proves and the flame is too low to light the main burner you can have gas spilling out for a while before it ignites and it can cause a small explosion. How bad do you like having eyebrows?

 

[MrMark]

Typically you are looking for the smallest possible pilot to prove your flame and light your main burner. If the thermocouple proves the flame your burner should light within a few seconds of activating the main valve.

If the main burner fails to light within 1-3 seconds you should adjust pressure or thermocouple height.

The fail proof way is to set the pilot pressure to manufacturer spec. and adjust the thermocouple just high enough to prove the flame.

The only real danger is if the pilot proves and the flame is too low to light the main burner you can have gas spilling out for a while before it ignites and it can cause a small explosion. How bad do you like having eyebrows?

My valve Honeywell seems to do all these things, the flame on the pilot is just WAY too large. I believe it has always been WAY too large. I just now serviced the unit and after figuring out what the NOx rods and coils were, noticed the excessive pilot flame. This pilot flame covers the flame sensor and lights the burner just fine. It is about 1-2 inches too long though and I need to figure out how to turn it down.

This pilot is almost touching the heat exchanger metal.

 

[Hlidskjalf]

Where the pilot enters the gas valve there is usually an allen screw that sits flush with the gas valve. It is usually nearby and marked "pilot". It might be hidden or in behind. You normally remove that screw and there will be the adjustment screw that you can usually get at with a small flat. Turn in (clockwise) for more pressure, turn out for less.

I say "usually" because most gas valves are different. But this is typically how Honeywell valves are setup.

 

[ZeroSignal]

I can't see your picture? It has a cap (Phillips screw) that removes to allow access to a small slotted screw in a bore. It is right next to the fitting for the aluminum pilot tube.

There is a larger, easier access, plastic slotted screw on the regulator. I wonder if that is the main regulator adjustment?

You are correct..I wouldnt paly with regulator adjustment unless you have a manometer on your burner manifold

 

[MrMark]

You are correct..I wouldnt paly with regulator adjustment unless you have a manometer on your burner manifold

Yes, I need one of those. I want to check that. Do you know where can I get a decent or even halfway decent one? Do you have any links so I could get the idea of what I am looking for?

 

[ZeroSignal]

You can probally get one at alot of commercial plumbing supply houses or probally grainger, johnstone supply, sid Harvey, etc. Don't think you need an expensive digital one standard tube style should suffice here.

 

[MrMark]

Here's the manometer I bought

http://www.amazon.com/gp/product/B001TOHT78/?tag=atomicindus08-20

The furnace service instructions state to adjust to 3.5 inchs W.C. with the burner on. Talks about removing a cap and turning a screw. Anything else I should be aware of?

It states to use a U shaped manometer from 0-12 inchs. The one I ordered is not U and not 15 but I figure it should work just the same.

I know that the installer never touched this thing or even read the directions. I have noted and corrected numerous problems with wiring and I even had to move the pressure switch to the correct location. I am certain that he never tested the valve pressure. There is also not the required 6 inches of clearance on the louvered front.

Everything I pay for someone to do ends up a butcher job. And, people wonder why I do stuff myself.

 

[ZeroSignal]

3.5 WC is good as long as your natural gas...

 

[Cast Iron Nuts]

Boom Now call the insurance company. Call a licensed gas fitter that's why they exist.