Another newbie question! Pilot light

Mamamahala · 10-03-2023, 10:22 AM

I am attaching a picture of our Dometic furnace interior.... It has a push ignition. The blower works when the thermostat is turned up, but it won't light. There is gas to the camper as the stove burner's work. Our question is..... Where is the pilot in this thing?!?! There is a small hole on the cover (not pictured) but there is nothing behind it that looks like it would be the pilot light.
Thanks!!!

**JohnB** · 10-03-2023, 02:58 PM

Hi,

Please take a picture of the Model numbers for your furnace to help better. Also, what year camper is this? By the one pic, it appears to be an older Hydroflame FA 72 or an FA 79 Atwood series furnace. Atwood bought Hydroflame, and then Dometic bought Atwood.

Also, take a picture showing what that large black cable hooks to.

I am not the guru on these old furnaces, but it looks like you have a pilot gas valve that uses a piezo lighter. With the blower running, when the pilot gas is enabled (you are pushing and turning the knob), the piezo lighter, pushed by hand multiple times, would create the spark to light the pilot. You do not light this with a match or grill lighter.

Please review page 5 of this manual in our FILES section for the complete lighting instructions if yours is an FA-79 series furnace. Look under SEQUENCE OF PILOT OPERATION. https://www.sunlineclub.com/forums/d...o=file&id=5639

If the gas valve works correctly, the pilot flame will heat the thermocouple and keep the pilot lit. You need to hold the valve knob in, at the pilot position, for a minute or until the pilot will stay lit. Then you turn the control ON, the pilot should remain lit, and the pilot is ready when the T stat calls for heat. When the T stat calls for heat, the blower has run fast enough to enable the sail switch and time out for the chamber air purge, and then the controls enable the gas valve to open. The pilot flame lights the main burner.

One of our members with one of these older furnaces can chime in better. I have never worked on one of these oldies, so there may be a step/trick not correct.

Parts are tough to find for these older furnaces. It all depends on what you need.
If you have never used this furnace, I would suggest having it checked by a service tech to ensure all the controls are working and there are no rust holes in the heat exchanger.

I hope this helps.

John

PS. If any of our Sunline owners have a user manual for this model furnace, please upload a scan or PM me, and I can help. I did find a user manual for an FA-79 series linked above, but not the FA 72.

Mamamahala · 10-04-2023, 10:58 AM

Hi again, John! Thanks so much for your reply. We have the owner's manual for the heater. I guess my question simply is, how do you know the pilot is lit? Where do we look? Sorry if this sounds ignorant!

And we have the HF-8012 (P) Hydroflame

**JohnB** · 10-04-2023, 07:32 PM

Ah, HF-8012 (P) Hydroflame. That is better; I can stop looking for the FA 72 or FA 79 series.

Yours is a Piezo light pilot; that is what the (P) stands for.

Not to know how you see the pilot being lit. I have yet to see one in person, but by the manuals, there is a "pilot observation port". See here

And see this thread by another club member asking the same thing. J52wf (Jim) answered him how he had to see his.
https://www.sunlineclub.com/forums/f...12p-12540.html

And here is a better pick by 1960Zimmer, who has lighting issues with his.

His post is here, https://www.sunlineclub.com/forums/f...ing-20587.html

This is what the pilot, thermocouple, and igniter look like inside from member Agrosso68.

His post. https://www.sunlineclub.com/forums/f...ict-12346.html

A club member who has one of the older furnaces may join in here and can tell how they see it. If you do not get anyone on this post, suggest creating a new post with the topic, "How to see the pilot flame on an HF-8012P furnace". And explain the issue. Your post my not be seen well with the title you have. You can even link this post to it is needed.

Hope this helps

John

Mamamahala · 10-09-2023, 01:21 PM

As usual, John, you are awesome! This all helps SO much! I'll keep you posted!!!

W duffy · 10-12-2023, 12:08 PM

I have a similar heater. If starting from cold you can feel the heat of the pilot by touching the elbow. At that point you can release the valve and it should stay lit. Obviously, don’t touch the elbow after it is running. My heater is a bit of a pain starting when it has been sitting for months, otherwise it works well.

sparkzaflyin · 10-12-2023, 12:11 PM

The pilot peep hole is located between gas supply tube into the burner and piezo ignitor wire entrance onto burner plate. It's ridiculously small, you have to almost put your head at floor level, at least in my 1988 T-1950. My start sequence consists of 1) Make sure your water heater pilot light is lit, if manual. This ensures adequate gas supply to the furnace. Turn the on switch on your wall thermostat then set the thermostat to its highest setting, let the blower blow for about 3 minutes, give or take. While leaving the on switch enabled at the thermostat turn temp lever down to the lowest setting until blower turns off. Rotate gas valve to pilot position, push in same, and strike the ignitor 10 times or so, while pushing in valve. If there is no air in gas line and ignitor is good it should light. I wait 5 minutes and see if the hot air discharge is getting warm. If it is, pilot is lit. This guy's too old to get on his hands and knees looking for teeny pilot lights!