Please help with burner problem!!

[Docker89]

Hi, I purchased a used jotul dv400 natural gas stove and have been unable to get the burner to ever operate correctly.

The thermopile reads 550/280 and I have cleared ALL possible lines and orrifice for a possible blockage.

The pilot light works perfectly and produces a strong blue steady flame. but when I engauge the on/off switch for the valve I only get a few VERY short small faint blue flames that come out of the burner closest to the pilot. I have been working on this problem for many hours and can't figure out what it could possibly be. Any help would be greatly appreciated!!
Thanks

 

[DAKSY]

Remove the glass. Take a pic of the log set if you don't have a manual. Remove the log set. Remove the ember material. Pull the burner tube or pan.
Using a 1/2 inch or a 13mm wrench/socket, remove the burner orifice from the burner gas supply tube. Using a pipe cleaner or a Q-Tip, swab the inside of the supply tube to see if you have a spider's nest in there. Reassemble the burner orifice & reposition the burner tube/pan. Give it a try. If it works reassemble everything back to the way it was & let us know. If it doesn't work, let us know THAT, too & we'll look somewhere else for the solution...

 

[Docker89]

Thank you for the reply and suggestion. I pulled the burner orifice and found the lines to all be completely clear. Could this be a faulty gas valve? I don't have a gas pressure manometer to test the pressure coming and leaving the valve.

Thanks

Remove the glass. Take a pic of the log set if you don't have a manual. Remove the log set. Remove the ember material. Pull the burner tube or pan.
Using a 1/2 inch or a 13mm wrench/socket, remove the burner orifice from the burner gas supply tube. Using a pipe cleaner or a Q-Tip, swab the inside of the supply tube to see if you have a spider's nest in there. Reassemble the burner orifice & reposition the burner tube/pan. Give it a try. If it works reassemble everything back to the way it was & let us know. If it doesn't work, let us know THAT, too & we'll look somewhere else for the solution...

for

 

[DAKSY]

Could be the valve, but you need to check the pressure.
Tell me what you've got feeding the unit.
What diameter is the gas pipe & how long is the run?
What type of pipe? Corrugated SS? Black Iron? Copper?

 

[Docker89]

I took a picture to give you a better idea. Is there anything wrong with this set-up?

 

[DAKSY]

That looks ok. We need to know the size & the length of the run (in feet) that feeds it. Natural gas works on volume. If the length of your feed line is over 30 feet & the diameter of that line is only 1/2 inch, then you're not getting enough gas to the valve. A manometer will be needed to verify the gas pressure.

 

[Heatsource]

maybe it was converted at some point and there is an issue with the regulator
(my best guess based on the info provided)

 

[coaly]

If the unit sat a while disconnected for sale, mud daubers, spiders, or other insects can get into the valve inlet and get debris to partially plug or prevent valve opening. People never seem to put a simple piece of tape over the inlet.............. Not all have a screen.

Did you try tapping on the valve with it calling for main burner on? They can stick after sitting as well.
I'm not saying when all else fails, hit it with a hammer, but I've seen MANY need a tap to get working after sitting the summer season. Tapping the inlet line with a wrench is sometimes all they need. Don't be surprised if it lights right up - floor furnaces are notorious for that in damp crawl spaces when setting idle for months. When the thermopile is generating, some current is used to keep the electromagnet coil in the safety portion of the valve energized (open) so you only have a small amount of voltage left to open the main valve, which on many newer units can have a double shut off inside to have to open.

When they work with a switch at valve, but not with thermostat;
When a thermostat is used across the room, the DC current from the generator has to make it all the way to the thermostat, through the points and back to gas valve. (the reason only a millivolt thermostat should be used) So the wire gauge and voltage drop becomes important. One test is to jump the terminals on the valve to make sure the switch or thermostat and wiring is passing enough current. Direct connection with a jumper or screwdriver gives it a little more current, eliminating and voltage drop you may have in the circuit. Including your simple off / on switch if that's all it has. Those connections on valve and switch have to be very clean as well.

Keep in mind it's USUALLY not a "gas" problem but electrical from poor connections at limit switch, terminals, twist connectors....... As a gas man, I used my voltmeter and electric tools to cure most gas appliance problems more than gas flow problems. (other than a simple pilot cleaning)

 

[Docker89]

Thank you both very much for the suggestions.... The unit was sitting for a long period of time in a garage prior to the party selling it to me. The stove is supplied with 30' of 1" pipe. I have tried repeatedly to tap the gas valve with a wrench with the on/off switch engaged. The unit its not hooked up to a thermostat so that's not the issue.

why can do a few burner holes produce VERY small blue 1/4" flames near the burner but thats it? is it possible that the valve is only partially opening? I have heard from technicians that "servicing" valves is not really possible and usually just replaced. Is this my last option? Or is there a way I can clean out or manually open and "un-stick" the gas valve?

thank you again for your help and suggestions...

 

[Docker89]

The owner of the stove told me it was used with natural gas.... how can I double check and tell the difference in the regulator to be sure it wasn't for some reason actually set up for propane??

 

[coaly]

If the appliance regulator was set for propane, it would have twice the pressure. LP requires twice the pressure with about half the size oriface hole. So the regulator is actually blocked open in the LP mode and the pressure is regulated by the system regulator. If it were a pressure problem, not having pressure or volume to the burner, the pilot would drop down or go out when the main burner opens.

As Daksy said, normally a manometer or U tube gauge is put on the supply or taken at a pressure tap on the service valve. You can also put it on the oriface to see what pressure is passed through the valve when on. Valves are not "field repairable".

Does the valve make a slight click when you turn the burner switch on ? This would be the magnet energizing and physically moving the steel shaft in the valve. That doesn't mean the rubber part that allows gas to flow is opening fully. (the case when you tap and it opens) Does the switch have wires going to the valve? These would be the terminals on the valve to connect or jump to make the valve open.
With the switch disconnected, you should have continuity between those two terminals on valve showing resistance through the magnet coil. It simply makes a magnet inside when current from generator is passed through coil windings. Valve is spring loaded closed inside.

I assume the gas valve (also called safety valve) has a knob with off / pilot / on ? After lighting pilot, does it turn all the way to the ON position freely? When you hold the knob in at the pilot position, you're actually holding the (safety) valve open and pressing a steel shaft that's spring loaded closed, against the electromagnet head. When it starts generating, the current flow through magnet coil holds the valve open for you just like you're pushing it in. When it closes due to low voltage from dirty pilot, or pilot outage, it stops all flow through valve, so you're problem is not due to the safety system in the valve.... Nothing goes to the main burner passages in the valve until turned to on. Is there a section of valve with a "low - high" flame setting ? This is a regulator or restriction of sorts to control BTU output on some models.

Remove the tubing from gas valve to oriface and blow through it to be sure it's wide open? Spiders will crawl through main oriface and can build a cocoon like plug in the line behind oriface or even inside valve.

 

[WiscWoody]

It looks like the flex gas pipe is kinked. If so it can limit your gas pressure needed for the burners but it will allow the pilot to work as usual.