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 Jotul 100 Gas room heater sparker won't ignite gas

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chas
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chas

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PostSubject: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeOctober 1st 2018, 6:53 pm

Yeppers, bought the Jotul 100 new in '89.  The one on the lower left..
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Spark igniter has always given problems. Despite spark, gas won't ignite, so I've been torching it all these years. So last week I though I would take another look at what is going on. PLUS remedy another ignition issue. When first lit (torched), pilot is fine, if any burner is turned on in 3-5 minutes, pilot flame is pulled up and goes out. Then it has to be re-lit... Now once the pilot has been lit for several hours any burner will light fine. Studied intently. I came to the conclusion the the cold flue, 4", some 7' of black 4" vent pipe to 5' of 4" Metalbestos gas vent pipe. Initially generates a tremendous draft, despite the air break built into the stove. once the flue warms the excess draft goes away. The igniter assembly, Junkers CB-505 135, is German made and no parts are distributed in the USA.
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Similar but not identical:

So, to fix the pilot blowout I fashioned a bottom side baffle for the igniter to keep rising draft from blowing it out.

However, in doing so, all the manipulations, the thermocouple gave up, corrosion around the shank parted the external sleeve opening the circuit. Again the thermocouple is Junkers but obsolete, not even a replacement can be found, it has an 8 mm threaded nut to attach to the 4-way safety valve. I looked all over the web and found a "replacement" in New Hampshire, but the image is not good enough to determine just how the adapted is going to work. I need to know, and I suppose I could have called New Hampshire.

However, I keep relatively good files on my appliance and discovered the Mom & Pop shop that sold me the Jotul is still in business. They have the same thermocouple with the adapter.. Yowsa! same price as New Hampshire except no $17.00 shipping charge... So this past Friday I picked up the Thermocouple. Got it installed and it works fine. The adapter is made from a compression fitting male to male coupler, with a slot milled lengthwise that the casing of the thermocouuple slips into, the 8mm end threads into the safety valve, the 9 mm end does nothing also the 9 mm original nut... It is a SIT thermocouple.

The homemade air baffle works a treat but I still have to hand ignite. So I decided to tinker with the igniter electrode, it is removable, like a spark-plug, so I decided to "bend" the already bent end to close the gap. Oops, the electrode is not steel or stainless steel, it appears to be tungsten, I snapped it at the OEM bend Sad Sad

I asked at the Mom & Pop, and was told the electrode is unobtainium... You just can't tell that to a radio collector, no way! So the quest is on, looking for a replacement igniter electrode for a Junkers CB 505 137 (750).

I discovered the electrode [You must be registered and logged in to see this link.] 810 7078 may well be what I am looking for. Here is the rub, all the sellers are in Europe, mostly Germany.. Some show a picture some have dimensions, all those sellers require me to sign-up and be a gas technician... Then there is VAT and possibly import duty.

I also found a complete Junkers pilot igniter assembly, slightly different but may work, from $77 to $108 not including VAT and shipping... A pig in a poke... No dimensional information at all.

So I am going to try and make a part number association for the igniter with an image that has dimensions on another vendors sight to confirm the correct part number, then order from ebay Germany, vendor says will ship U.S. but does not publish the rates, email for rate...

The "found electrode", the bend is closer to the ceramic body than on the OEM. But, if the notch key gets the tip to where it works, fine, if not the Dremel will "fix" the keying problem. I need only to confirm the body dimensions...
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Now if there is a European gas stove expert with a store full of Junkers igniter electrodes and a ARL member, sweet!

Essentially, replacing the electrode gets the spark back to the flame spreader where it was initially, but, will it ignite repeatably I still do not have an answer for that problem!

BTW the electrode is keyed and the offset can be placed in only one position. Since the electrode tip cannot be bent I cannot get the spark to a location on the flame spreader to encourage ignition.

The plan is to take the Dremel and carve off the internal key that keeps the electrode in one position so it can be turned to a closer location to the flame spreader. I'll determine that when I get a new ignition electrode.

Is there a gas expert out there???

Chas
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Cliff Jones
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Cliff Jones

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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeOctober 23rd 2018, 3:15 pm

not an expert but are you sure the thermocouple is working or the thermocouple solenoid?
Some time tapping the solenoid will free it. I have a DuchWest, ran into that problem the second year I had it.

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chas
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeOctober 24th 2018, 10:44 am

Cliff,

A bit of an update:

The OEM thermocouple was shot, the outer sleeve at the tip had eroded where it it is held in place by a spring steel sleeve. This erosion separated the sleeve which is an electrical connection. I would expect this, something I have seen working on heater bands on injection molding machines. The constant heat and dissimilar metals causes the failure...

Problem is the OEM solenoid safety valve, a 3-way/pilot and igniter has a 4MM thread for the thermocouple. The length of the thermocouple is unique to the stove at 1 meter. In other words the thermocouple was made specific for the stove. However, a "general replacement" is made BUT its connector is 5MM. So what gets provided is a 4 x 5 male union of which has been slotted to fit over the thermocouple wire. As you know the thermocouple is a coaxial arrangement. The captive 5MM nut is slid back out of the way.

So that fixed the thermocouple.

Last Friday, the Zündelektrode for the Junkers CB 505 was received in USPS from Germany, an ebay purchase. Paid a premium but I had to prove that it is not the "spark-plug".

I had attempted to re-position the OEM Zündelektrode tip, I was unaware that it was tungsten, it snapped at the bend, still sparked but would not touch off the gas...

So the new Zündelektrode was installed, tried to light, NUTS, the spark still won't light the pilot...

It is fixed, but I was unable to correct the spark ignition which means I have to torch the pilot if the flame goes out. No biggy, I have been doing it for years.

I often wonder if it is the fact that Eversource (gas provider) has reduced the BTU in the gas, something I noticed 25ya when we once had gas that had a rich dark blue flame, now its a whispy light blue. I recall having to re-adjust the secondary air shutters on the gas cook stove and the hot air furnace.

I know the BTU is controlled, I once toured the local gas distribution telemeter station. There was a flame behind glass, in a large rack cabinet. Real time BTU analyzer that controlled the addition of inert gasses to the mains remotely at pipeline regulator stations.

The spark annoyance came true this morning, severe thunderstorms last evening, occasionally I get a strong down draft in the 4" gas flue. Blows out the pilot, so I have to torch today...

So why not a wood stove? I have asthma, burning wood is a big aggravation. This stove does not require an electrical connection. So long as gas is supplied, loosing electricity won't prevent heating at least part of the house. The cook stove as well, gas pilot ignition, no electronics.

Chas
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FrankB
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeOctober 31st 2018, 6:08 pm

From the lesson in gas I was given is that the thermocouple puts out a few millivolts,(Can't remember exactly, 2-4??) which provides the voltage to hold the gas valve solenoid open. You can measure the output from a thermocouple with your meter.

Any way you can scavenge the gas regulator/solenoid/ ignitor assy from another gas heater, and modify it to fit? I don't have AGA certs, so am not trained on that stuff.
 Now I have seen the system you pictured somewhere..... Maybe a BBQ or camp stove that runs on LP OR was it a stove, fridge, heater or water heater assy out of the motor home I scrapped years back???
 Just for fun, check with motor home repair shops.
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chas
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeNovember 1st 2018, 3:09 pm

Frank,

I DO have the stove going...

The new Zündelektrode does spark. None the less the spark won't "touch -off" the gas at the pilot. So I still have to torch the pilot, I keep the torch on to heat the new thermocouple, saves time keeping the control valve depressed. Once the milli-volts is up the solenoid holds and the main gas will tun-on...

BTW the standard is 40 millivolts. FWIR it is a copper constantan thermocouple (TC). The current is achieved when the mating of copper/constantan at the cold junction which is the termination at the gas safety solenoid. Copper/constantan is "supposed" to deliver more current into a load than say Iron/Constantan "IC" TC

If one reads the hot junction with an uncompensated voltmeter the new cold junction is the plating on the tips of the meter to the TC extension. By looking up a TC millivolt to temperature chart one can determine how hot the TC is. The chart is specified as to the cold junction temperature or to absolute temperature.

For an absolute chart a pair of cold junctions is used in a melting ice bath 32 deg. F.  << real easy to make...

One of my first jobs as an instrument repairman was to calibrate TC instruments and chart recorders. I had to know TC's up/down/sideways.  It was fun stuff.

So the TC and the 3-way gas safety valve are working fine.

It is some sort of a combustion issue with my natural gas, the spark just won't ignite it...

Have a nice day! BOOM!

Ooops....

Chas
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Cliff Jones
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeNovember 1st 2018, 7:13 pm

A close friend of Mine retired about 3 years ago. He was working for Industrial Furnace and I'm sure He had many problems to overcome in furnace controls. He went as Far as China to provide services. He loved His job so well that even after He retired He would get a call "Just this one time request" that happened till finally His wife said enough is enough. He was just an old softy. I went with him to a Metal tempering shop that had at least 12 burners in one oven that had to be balanced and repaired because another Company came in and fouled things up. This happened a lot. HE commented to me that he Ran into lot of people that claimed they were experts, that really were not.

In the shop I worked in had a Temperature Calibration Lab. They had at least a dozen Temperature Pots and 2 or 3 Cold temperature pots. Some used sand as a medium and antifreeze in others.

This was just about the time there was a change over to digital sensors. Of course they had several types of thermocouples to deal with. Time charts and a lot of calculations before computers came into the Picture.

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Cliff Jones
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeMay 30th 2019, 12:01 pm

Had my Gas Dutchwest converted from Propane to Natural Gas, yesterday.

EDIT_Note : I sent this to a Friend of mine who I have known since my High School Days. So this has been edited because of His comments and Expertise of 47 Years in Working on and installing and troubleshooting Industrial Furnaces.

If you cannot get the heat to come on, or takes longer before coming on there may be some crud inside of the gas pilot orfice. Since its restricted the gas, there is no longer sufficient heat for the heat sensor. The heat sensor sends a milivolt signal to the gas valve switch, which is reduced because of less heat.
You can test this with a bypass switch because of the short (3-5 foot) wires involved.

The thermostat on the wall has very small wires and the length (12 feet or so) reduces the millivolts to and from the thermostat enough so the solenoid cannot engage.
Where as the bypass switch has larger wire and is shorter so less of a voltage drop. Remember its millivolts so the effect is greater.

One of the things the installer told me,is there seems to be more trouble using Propane then Natural gas as far as maintenance goes.

(Which isn't true, as both are about equal.)

Another Phenomena is when the stove first comes on there is less air so

( Again at least that's what the installer told me which is a load of baloney According to my friend .)

The flame starts out blue.

A Stove pipe has what is called a direct vent. it has two chambers, one to exhaust and one to allow fresh Air in the stove. and as the stove heats up there is an air downdraft that increases to replace the heated air as the heat rises in the stove pipe.

With its increase of time the Flame color (at least as far as Dutchwest stoves literature) has a tendency to increase and have more of an orangeish yellow flame.

Note: It starts out blue because of more oxygen.

In natural gas the flame is a little higher than propane. However Propane has a Higher heat value but is not significant in a stove.
Propane is higher in cost per BTU than Natural gas or Electrical Heat.
And natural gas is cheaper per BTU than Electrical Heat.

See what I done Taught you?
You can prove this by rate cost per BTU's of Each heat source.
If you are charged by the gas company by Therms you will have to convert to BTU's, Just so you know. study

As I noted my friend called me after I sent him this post. So that's the reason for corrections.

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Last edited by Cliff Jones on June 1st 2019, 11:27 am; edited 2 times in total
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FrankB
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeMay 30th 2019, 6:17 pm

You can also measure the output of the thermocouple with your voltmeter. I -think- its like 2-5 MV.
 They often fail more than any other part, plus keep a spare orifice too.
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeMay 31st 2019, 10:51 am

Anywhere from 185 mV up to as high as 500mV or more . There are some Pilot assemblys that use both a Thermalpile and a thermocouple. 185mV is considered the absolute minimum for proper operation.

Here's an interesting quote from Hunker.com.

"Gas fireplaces and fireplace inserts use thermocouples and thermopiles primarily to generate electricity. When turned on, the pilot in a gas stove generates heat, which travels through a thermocouple. As the heat reaches the second junction of the thermocouple, it generates electrical voltage. The fireplace uses this voltage to open the gas valve, allowing gas to flow out and start a fire. Because thermopiles generate more electricity than thermocouples, fireplaces with thermopiles can connect to thermostats for temperature control. Fireplaces with thermocouples lack sufficient electrical current for this."

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chas
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeMay 31st 2019, 2:07 pm

Well I lit the pilot by hand last Fall and it is still lit.

Oh, I did put the new thermocouple in, it is a "modified" thermocouple. The mounting nut provided was the wrong size so a nut with a slot is included. The "Mount" is into the solenoid control valve, again another European job, a three position valve also with a pilot and off position. The orifice for the pilot is in the igniter assembly.

As I said last Fall, the igniter has the new spark plug, it sparks but the gas still does not light by spark.

I also tried to solve the problem of the pilot flame blowing out as the unit warms up from a cold start. I tried a baffle, but no matter how small I made the baffle, the area around the pilot burner got really hot. I did not want to risk melting the pilot assembly. So when the safety pilot goes out or is shutdown a relight must be with a torch and the torch kept in play for five minutes until the draft no longer pulls out the pilot flame.

A little forensics on the thermocouple, seems the may years under the heat erosion too place on the body of the thermocouple about an inch back from the tip where a spring sleeve grasps the body of the thermocouple and holds it to the aluminum body of the igniter assembly. The erosion eventually made it all around the external sleeve which is an electrical conductor. One the last bit of metal eroded away the thermocouple lost voltage.

Essentially back to normal working broken... Neutral

Chas
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Cliff Jones
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PostSubject: Re: Jotul 100 Gas room heater sparker won't ignite gas   Jotul 100 Gas room heater sparker won't ignite gas Icon_minitimeJune 1st 2019, 11:17 am

One thing I didn't Mention, that is to clean off the Thermopile as any crud will be a barrier to the flame and reduce the milivolts produced. (this is from several sources)

Also if having problems, you might replace the thermost wiring with larger wires, because of Ohms law, especially dealing the millivolts in smaller wires (more resistance, hence I.R. voltage drop)

I went on the Web to a related Youtube topic, and that person was having trouble with His gas water Heater in the garage, it would work for two months then shutting off repeatadly.

He discovered that his storing of cat litter produce minute dust particles that were drawn into the flame and coating the thermopile. He started to clean the thermopile using fine steel wool. Problem Solved. (He mention He had several cats).

I imagine the cats did there thing in the garage. pale stiring things up or getting a fresh supply from his stash.

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