Osburn vented propane room heater, Model G2

[Giznawz-old]

Pilot flame lights and stays lit and burner starts when remote switch is flipped on.  After about 5 minutes something clicks and the burner and pilot light go out.  The pilot will relight but will not stay burning without holding down pilot prime for about 10 minutes, after which time the pilot will light and stay lit, and the pattern repeats.

I assume that something is overheating, and that the click is a safety of some sort cutting off propane.  After 10 minutes, it has cooled enough to relight, but quickly overheats.

Any ideas for troubleshooting?  How shall I proceed with diagnostics?  Let me know if any more info is needed.

Thanks in advance!

[RegUS_PatOff]

this may be your manual:

OSBORN GAS FIRED DIRECT VENT HEATER

[applianceman18007260692]

If your heater is equipped with ODS system then the pilot is probably dusty. I like to flush out a pilot using rust buster. Messing with the flaps on them ODS pilots can screw them up.

[ACtechGUY]

IF the manual that RegUS_PatOff posted is even close to being the correct product , then I would look real close at the blower. Sounds like you have a classic low or no air flow problem.

This type of setup has a over temperature safty switch in line with the pilot flame (thermopile) circuit. When the safty switch overheats , the circuit is interupted and the pilot flame goes out.

Maybe the motor is not pushing enough air for some reason. like ,If there is a filter, it may be dirty. Or if the motor has a capacitor , the capacitor may have failed. Is the air intake blocked?

[Giznawz-old]

hi guys.  Thanks for the replies.  I should mention, after re-reading my original post, that I may have been misleading in the way that I worded my problem.  When I said, "The pilot will relight but will not stay burning without holding down pilot prime for about 10 minutes," I meant that for about 10 minutes after the flame goes out the pilot will light but will not stay lit without continuing to hold down the pilot prime.

At any rate, the manual that Reg posted is the correct one.  My unit has no air blower.  I don't think that it has an ods, but I could be wrong.  I think that I have identified the part that is tripping, keeping the unit from relighting until it has cooled.  The part I am suspicious of is on the back of the unit, wired to the controller.  It has a metal tab lightly resting against the flu.  I suspect that it is a flue temperature switch.  When I push the tab away from the flue it audibly clicks and the burner and pilot go out.  So it seems that either my flue is overheating or this switch is over sensitive.  What do you guys think?

 

Thanks again!

[Giznawz-old]

I'm having trouble linking my photos.  Let's see if this works...

[Budget Appliance Repair]

I don't have an actual parts list for this unit and the info in the link doesn't have any parts listings in it.

From that picture that looks to be something that was rigged up by someone besides the manufacture of the furnace.

Those wire connection terminals that are crimped on are definitely not factory.   What you would normally expect to see at that point is a thermal snap disc t-stat that is used as a vent rollout safety.   If the vent isn't drawing correctly then the area gets too hot and trips the thermal disc to shut down the furnace.

The switch that is there now is just a micro-switch with the lever touching the vent pipe.   About the only think this switch can sense is if the vent pipe isn't connected, there is a possibility that this is a factory part and that is the actual purpose of the switch because this is a direct vent furnace that draws its fresh air in from the outer section of the same vent that the exhaust flue it vented out the middle and you would not want to run this furnace without the correct air inlet/vent pipe attached.

Being that this is a direct vent furnace, I don't believe it would have a vent rollout safety since the burner chamber is sealed and shouldn't be able to spill any flue gases out into the room.

There isn't an ODS on this unit to worry about and the click/pop noise that you hear when the unit shuts down is most likely just the pilot safety magnet releasing caused by either a faulty switch, (the one in your picture), overheating or if this the actual factory placement of the switch maybe the bracket that it mounts to is made to move when it overheats in that area to shut the furnace down.    The other thing that could make the pilot safety magnet release is if the pilot flame isn't burning correctly, (dirty pilot orifice, too small of flame or out of position thermocouple).

The 10 minutes that you have to wait before you can get the pilot to reset and stay burning after it has went out leads me to believe maybe that switch is serving it's purpose and shutting the unit down for some reason.

[applianceman18007260692]

Show a photo of the gas valve and we will know what you have.

[Giznawz-old]

Here are some photos of the unit, and of the controller, electrical doodads on the back of it, and of the burner and pilot.

http://picasaweb.google.com/101004626903423632827/UntitledAlbum?authkey=Gv1sRgCPfxj-XMj5bfSg&feat=directlink

[applianceman18007260692]

That is a millivolt gas valve. It uses a pilot generator as a pilot safety plus the generator produces the power to operate the heater's solenoid inside the gas valve. If the pilot is going out after 10 minutes I suggest the generator is getting weak. These pilot generators are not cheap. Because they function as the main power that operates that gas valve, they are not like an ordinary thermocouple.

When these get weak they shut down as the thermostat begins to cycle on and off.

[Giznawz-old]

Is this what I'm looking for, then?

http://govex.ngap.com/product.aspx?zpid=2204520

or

http://www.pexsupply.com/White-Rodgers-101934F32-750-Mv-Generator-For-Use-With-PG9-Style-Pilot-Burners-32-Cable-F-Spade-Clip-14217000-p

Thanks for your help!  I couldn't find any at repairclinic.com.  do you recommend or affiliate with a vendor for these?

Thanks for your help!

 

 

[applianceman18007260692]

Either one I see will work. Those seem to be some great deals by the way.

Before ordering anything first see if that old generator comes out easy. Some of them fall apart. If you order the PG9 pilot assembly make sure the one you order mounts correctly. You wouldn't want one that mounts on the wrong side of the burner. They come in left hand or right hand mount.

[Giznawz-old]

Thanks again for your help.

Here's what I've done so far: http://picasaweb.google.com/lh/photo/_GJhD1OPn8m5QyBlklefv-aG8q7PgixGA8Kv1_uJVqw?feat=directlink

I got the generator off the pilot assembly pretty easily, so that shouldn't be a problem to reassemble.  I'll order the second of my 2 options from the previous post since I don't need to replace the whole assembly.  The gasket on the burner cover plate ripped during disassembly.  I will need to replace it and the putty gasket on the wire cover plate.  Should these items be readily available at a local furnace shop or will I need to order replacements off the internet?  What should I ask for when I go to replace them?

Thanks again. 

[applianceman18007260692]

Tough questions. Finding a website to replace these things id tough indeed. Maybe someone will respond.

[ACtechGUY]

There are high temp silicones that are used to replace fiberglass gaskets these days. Something like this..http://www.fastenal.com/web/products/detail.ex?sku=62491 will work for you.