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harum · Dec 4, 2013, 10:11 AM

Hello! It's getting colder with every day, so I somehow have to fix our furnace. It's an older model that came with the house (please refer to attached photos), which worked fine when we tested a few months ago. Looked like the pilot had stayed lit for years and years before I shut down the gas main to install gas dryer. The furnace pilot went out and I can't light it back on, unlike the gas water heater pilot.

I would like to find a troubleshooting manual/procedure to see what's failing and if this is something I can work on myself. I have contacted the manufacturer with emails and phone messages -- to no avail: no response whatsoever.

It's also good to know what's wrong before hiring a HVAC person.

What I have tested: the fuse is good; the power is supplied; the mercury switch is sparkling when switched; I smell gas when trying to light the pilot.

Any suggestion would be greatly appreciated!

hkstroud · Dec 4, 2013, 11:37 AM

Does this furnace have a standing pilot light or an electronic igniter?
Are those the lighting instructions behind the gas valve

harum · Dec 4, 2013, 12:18 PM

Originally Posted by hkstroud

Does this furnace have a standing pilot light or an electronic igniter?
Are those the lighting instructions behind the gas valve

Yes, you are right, those are the instructions. Looks like a standing pilot light to me, the one you have to light with a match -- isn't this what the instructions say?

Looks like the pilot is dirty or out of adjustment, even though nothing has been done to it since its working times.

harum · Dec 4, 2013, 01:05 PM

Well, thanks for the feedback. I have tried repeatedly and the pilot is finally lit and stays up. Removing one of the covers to bring a burning match right next to the pilot opening helped.

The only thing that worries me is that the pilot flame is pretty strong: it well overshoots the thermocouple and heats the metal surface behind to a red hot (as in the image attached). Is there a way to turn the pilot down a bit?

ma0641 · Dec 4, 2013, 01:27 PM

On some of the older valves, there is a pilot adjustment screw. In some cases you can tighten down the screw. In others, you remove the cover screw and the adjustment is underneath. I believe the screw in the picture is the hold down screw for the thermocouple assembly. The new heaters of course save money by not having a pilot.

hkstroud · Dec 4, 2013, 02:09 PM

I agree with Brian, there should be an adjustment on the gas valve for the pilot light. Keep in mind though that the pilot not only heats the thermocouple, it lights the burner.

DennisMooreAC · Dec 4, 2013, 04:12 PM

I suggest doing a carbon monoxide check.

harum · Dec 4, 2013, 05:51 PM

Originally Posted by DennisMooreAC

I suggest doing a carbon monoxide check.

Thanks, a good point, totally forgot about it. The furnace itself is in a garage with a lower level of the floor. Do you mean checking the air pumped in the rooms for CO?

harum · Dec 4, 2013, 05:58 PM

Originally Posted by ma0641

On some of the older valves, there is a pilot adjustment screw. In some cases you can tighten down the screw. In others, you remove the cover screw and the adjustment is underneath. I believe the screw in the picture is the hold down screw for the thermocouple assembly. The new heaters of course save money by not having a pilot.

Thanks Brian and Harold! This is what the pilot gas line has. The photos show the flame end and the other end, with just a bare line free of screws or anything in between. Can't find anything like an adjustment screw, not much to tweak here at all.

Could it be the screw on the right in the second photo?

DennisMooreAC · Dec 4, 2013, 05:59 PM

Check any areas with human habitation. 33 parts per million carbon monoxide starts making people sick.

harum · Dec 4, 2013, 06:05 PM

Originally Posted by DennisMooreAC

Check any areas with human habitation. 33 parts per million carbon monoxide starts making people sick.

Would a store bought CO senson/alarm be sufficient?

ma0641 · Dec 4, 2013, 07:22 PM

Don't think so. Hard to tell. If you Google the gas valve model #, it may show you a schematic. I would also see if the little red plastic cap ( if it is a cap)comes off, it may be under there although it looks like an index mark. One thing I would do is to shut things down and vac out all the dust and rust. Use a small vac and a paint brush. Pilot doesn't seem too big. First indication of CO is a headache.

hkstroud · Dec 12, 2013, 10:25 AM

Follow the pilot gas line back to the gas valve. Adjustment would be on the gas valve and should be close to the pilot gas line. Adjustment may be a recessed hex screw.

Carbon monoxide detectors in all sleeping areas is a good idea.

harum · Dec 12, 2013, 10:59 AM

Originally Posted by hkstroud

Follow the pilot gas line back to the gas valve. Adjustment would be on the gas valve and should be close to the pilot gas line. Adjustment may be a recessed hex screw.

Carbon monoxide detectors in all sleeping areas is a good idea.

Thanks! No, nothing around the pilot line that could be tweaked. Must be a really old model.

hkstroud · Dec 12, 2013, 04:47 PM

I certainly would expect there would be some means of adjusting the flame of the pilot.
Can you find make and model of gas valve?

harum · Dec 13, 2013, 01:39 PM

Originally Posted by hkstroud

I certainly would expect there would be some means of adjusting the flame of the pilot.
Can you find make and model of gas valve?

Thank you. The valve model V8243A1084-1 by "Honeywell". Looks like I have to take the cover off. Nice image!