Rheem forced hot air w/ standing pilot light

[Danny P]

I have an older Rhemm forced hot air system with a standing pilot light...the pilot light appears to be low and the burners are not igniting when they should, sometimes causing a smell of gas throughout the house...I have changed the thermal coupling, but can't find an adjustment screw for the pilot...the Gas contol valve is a VR8200H-1004 can someone tell me if that has a adjustment screw for the pilot light, or am I looking at a more severe problem...Thanks in advance Danny

[HayZee518]

pilot flame etc.

I took the following off a honeywell site.

e thermocouple is the pilot's, well, co-pilot! It is the electronic device that senses if the pilot flame is hot enough to ignite natural gas or propane fuel to the burner. If the thermocouple thinks it's safe, then it keeps open the main gas valve located in the pilot assembly. If the thermocouple does not sense enough heat from the pilot flame (such as when the pilot is out), then the thermocouple shuts off the gas valve to the burners.

How the Thermocouple Works
So what is this thing and how does it work? Well the thermocouple (technically called a thermocouple junction) is a device that contains two metal wires welded at the ends and placed inside a protective metal case. The thermocouple sensor is found at the business end of the pilot flame and is designed to be placed in the hottest part of the flame. The other end is connected to the pilot valve body. As the thermocouple heats up, it produces a small amount of electricity and when it gets hot enough from the pilot, send a signal to open the gas valve by using a solenoid operated by a 24 volt transformer. The thermocouple calls the shots, and by converting heat to an electrical signal, it allows the gas valve to open or close.

Once the gas valve is open, gas is then constantly supplied to the pilot and as required for the gas burners (as called for by the thermostat). If the pilot goes out, then the thermocouple gets cold and produces no electric signal to open the gas valve's solenoid and the gas valve shuts off the gas supply to the pilot and burners.


If the pilot lights but the flame is a weak yellow flame, it will not get hot enough to heat the thermocouple to its set point allowing the gas valve to open.

A natural gas flame should be a bright blue with the tip of the flame having just a tinge of yellow. A propane flame should have a bluish green flame with a tinge of yellow at the tip. The flame should be strong enough to hit the thermocouple tip about 1/2 inch from the tip end. If the flame is weak or shaky looking, check to see that a breeze or draft is not blowing on it.

Adjusting the Flame
There is usually a small screw on the pilot valve body that will adjust the flame. You may have to refer to the manufacturer's instructions to find the screw. Turn the screw as needed to adjust the flame throw.

Yellow Flame
A yellow flame is caused by lack of air and incomplete combustion. It can be caused by a dirty pilot tube tip.

Split Flame
This is caused by dirt in the pilot tube. Take a needle or small nail and gently clean the tube.

Flickering or Wavering Flame
A flame that flickers is usually caused by a draft.

[Danny P]

Thanks...thats alot of information...I noticed last night the flame is keeping the thermocouple cherry red, so I think the flame is ok, but I noticed the furnace is firing out of order. When the thermostat calls for heat the inducer fan starts, but before the jets ignite the house fan starts, If I'm right the jets should ignite before the fan starts, I think thats why I'm getting that smell of gas...if I tap on the front of the furnace the jets ignite, telling me a switch must be hanging up, but not sure what switch it would be...would cleaning the contacts help...Thanks again

[HayZee518]

firing order

look at your schematic diagram at which switches need to be closed before the igniter or main gas valve opens.
the "chain" needs to be complete before the valve opens.
what is the color of the pilot flame? is it split?