Help with gas portion of dual-fuel Central Boiler

[Jon_E]

Kind of at a loss. I'm not a gas expert and don't know one. The burner was pre-installed at the factory and has never had a problem. Ordinarily when I turn the knob to gas only, I hear the following:

1. The motorized damper inside the boiler will open.
2. What sounds like an electric blower of some sort? Maybe a valve opening?
3. The "bzzzzzzzt" of an igniter lighting the gas.
and finally...
4. The sound of a full-on blue jet of propane flame (which I can see if I crack the door about an inch).

Lately I've been getting 1. only. No blower/air noise, no igniter, and certainly no flame. I am a little nervous about taking this thing apart. Should I? Is anyone familiar with these and can tell me if this is a user-serviceable problem or I need to find a plumber with a gas license? I know I have plenty of propane, and the valve next to the regulator (on the service line) is open. The thing quit working sometime in January, I guess.

EDIT: I should add, it's a WAYNE burner. Don't know too much else about it.

 

[heaterman]

I think there is a switch that has to prove closed on the damper in order for the sequence to continue. The damper must rotate fully open to close that switch and send burner voltage on down the line.
I know some are set up that way. Not sure about the Central so you'd have to check your parts list to see if something like that is in there.

If so, your possibilities are damper not opening all the way,
switch out of position,
switch defective,
or no connection between switch output to the burner control like a wire off or broken.

 

[heaterman]

This is basic info from a Wayne manual for their model 265 burner. In your case the call for heat would be initiated by an aquastat in the water jacket.


1. APPLIANCE CALLS FOR HEAT BY RAISING THE THERMOSTAT TO THE DESIRED SETTING: Note the transformer is always
energized with 110 volts.
2. When the thermostat circuit is complete, this allows 24 volts to coil side of the fan relay which are the bottom terminals.
3. Now that 24 volts (yellow wires) are applied to the coil, this in turn allows the 115 volt contacts to close thus allowing 115 volts to
flow to the fan across terminals #2 and #4 which are in series with the fan motor.
4. The combustion fan motor should now be energized.
5. With the fan energized, there will be a 30 second pre-purge.
6. The fan motor will develop 3400 rpm quickly causing the centrifugal endswitch to close. The endswitch can be identified by the two
red wires coming from the end cap of the fan motor.
7. After the endswitch makes, this allows 24 volts to the direct ignition control.
8. Now the ignition process will follow.
9. The direct ignition control will generate a high frequency spark at the same time the gas valve opens. The S87K has a 4 second
trial for ignition period. If after four seconds the control does not sense a minimum flame signal of 0.8 microamps then the control
will go into lockout. To reset the control simply cycle the thermostat off and then set it to the desired room temperature.
10. After the burner is operational, the control shifts into a rectification mode constantly monitoring the flame signal.
11. The burner will now cycle off and on based on the thermostat setting.

 

[simple.serf]

Start by making sure you have power to the burner and the damper assy in the boiler is working properly. Given that yours is showing no signs of life, follow the list above, in the order listed. If you dont feel comfortable with it, a good heating tech should be able to troubleshoot. They are a fairly simple, reliable burner and are pretty easy to work on. I just removed one from service that had over 120,000 hours of run time. In 21 years of 16 hour per day service, it had 10 fan motors (usually endswitch failure), 4 gas valves, 3 burner controls, and two ignitors per year.

 

[Jon_E]

Follow-up to my original post: gas technician showed up at my house today. If I had any experience at all with gas burners, I probably wouldn't have needed him. I also wouldn't have needed him if I had bothered to do any preventive maintenance or cleaning of the burner and the cover in the last ten years. In any case - the entire assembly was covered in creosote, spider webs, and various remnants of rodent nests (probably chipmunks). The blower fan was clogged with bits of leaves. The ground screw was rusty and not making good contact. The electrodes were filthy and all covered in creosote and soot. Everything got systematically cleaned and adjusted and put back together, and voila! fired right up. I am now officially off wood for the spring and can work on filling my wood sheds without worrying about how much green & wet wood I am burning.