I replaced my thermopile and gas valve on American Range deep fryer, pilot still won’t stay lit what do I do

[eritech1]

Not knowing the model #

Do you have a high limit thermostat on there? Sometimes they are resetable. It would have a red thin button.

[ectofix]

What bothers me is that those items were replaced without giving us any idea why. 

What were the troubleshooting steps leading the decision to replace those?  What was the thermopile output voltage?  What is the incoming gas pressure?  What type of gas? How is the pilot burner’s flame quality? …and other questions.

 

Usually the first thing to check if the pilot will not remain lit is whether the hi-limit is open (as eritech1 said).  If it’s resettable – and the pilot stays lit after that, then that could mean the operating thermostat is malfunctioning or has failed.  Hence – the hi-limit trips. 

Use of a VOM could quickly determine some idea of what’s going on.  Inspecting the sensing bulbs in the vat is another hint.  If the bulb for EITHER of the thermostats (operating or hi-limit) is knarled up, beat up, broken…or looks compromised in ANY way, then there’s the problem.

 

*********************************

 

I must presume that the OP isn’t a technician.  That’s why I find situations such as this also comical.  To save themselves from bearing the expense of a service call,  DIYers will simply order and replace parts…then MORE parts.  THEN they’ll come asking for help HERE when the problem still isn’t resolved…because NOW the cost for parts they’re buying is surpassing what a service call would have been.

 

There was probably nothing wrong with that valve OR thermopile.  With THAT, I have to wonder whether, upon their realization that THAT’S the case, they’ll go and try to return the parts they’d installed after realizing they were not  the problem.

[fixbear]

ectofix wrote:

 

There was probably nothing wrong with that valve OR thermopile.  With THAT, I have to wonder whether, upon their realization that THAT’S the case, they’ll go and try to return the parts they’d installed after realizing they were not  the problem.

You and I both know that that isn’t the case.  If it’s electrical and you opened it, you own it.  There is never any reason to just replace parts without knowing the exact problem and what caused it.  The only variation from that is a intermittent that will not present when you are there. Even then, recorders help.  They are definitely the hardest for all of us.

[fixbear]

I just reread through this post, and it occurred to me we never told Tony how to find and fix his problem.  So here it goes.

 

First thing you need is a good digital DVOM.  Digital volt ohm meter.  And a High temp thermal measuring device that will Accurately read 500 F  Also to work on a gas appliance, one should have a manometer. Can be digital or a board with a “U” tube half full of water with a ruler. And the necessary hose and fittings to connect to a 1/8 pipe tapping.. You will also need the related wrenches to open the tap hole.  Often Allen.

 

Now that you have the tool, lets get into what you are looking for. If the fryer has no pilot light lit, That means that either there is no gas, or no power to keep the pilot valve open,  Set you meter on DC millivolts.  Note that the millivolt generator (Thermopile) is connected to the common of the gas valve and another wire to the high limit. Power then comes back to the pilot coil of the gas valve. Then to the thermostat and back to the main coil of the gas valve.  Obviously that means the pilot has to be energized for anything to happen.  Place your meter probes on the pilot coil and the common. Check that the thermostat is off. Light the pilot.  You should see the voltage rise to greater than 550 milliamps.  The generator will accually make 750 milliamps no load, but the pilot coil will draw that down a bit.  Two thing are going to happen here. either you will have voltage, or you won’t. 

 

1)  If you don’t more your probe from the pilot terminal to the wire that goes to the high limit. It should read 750 milliamps because there is no load on it. and the high limit is open.  You can now let the pilot go out and change your meter to OHM’s  Check from the wire connection on the Thermopile to the wire coming down from the high limit.  It should read “0” or close to it. If not check the terminals on the back of the limit and the wires going down to the gas valve and pilot.  You can also check with the ohm meter at the safety high limit to see it it is ok.  If the high limit is open or shows a high resistance, replace it. Providing you did check the reset.

 

2)  If you do have power, but lower than 550MV, Check your pilot light. It is either not on the thermopile or the flame is to low.  Or you have connection resistance.  Solve that and your pilot will stay on. This is the point to shut down the gas and tap in the manometer. If propane you should have 11 inches of water. supply. If natural gas 7 inches.  If the unit has a secondary gas regulator at the supply pipe you will have to refer to the manufacturers spec for it’s setting.

 

Now that the pilot will stay on,  Turn the thermostat to 365F.  Thermopile voltage should stay above 400 MA with the added main coil load. Burner should light.  Monitor the oil temp.  A digital recording thermometer is my choice here. Like a Fluke 52 with a immersion probe. Once it comes to temp, watch for the range of cut in and cut out. And if it is going over temp.  Each manufacturer uses different spec thermostats,   So I cant tell you how wide a drift it will have.  But it should be a average of the setting.  If the cut out get’s above  400F Change the thermostat. It’s what is causing the high limit trip.  Be aware, cooking oil has a flash point of 450F  That’s why the high limit is so important.

[ectofix]

I like how aptly complicated your write-up is.  Because..it is.  I commend you on your time efforts to write that up.

 

ME?  No.

 

I don’t come here to explain to DIYers every single little detail on how to fix their own equipment.  Like I’ve said before, “You never know what others don’t know” – and haven’t a CLUE of this guest’s knowledge and capabilities.  For all I know, they’re either VERY knowledgeable and capable…and only require a little nudge to be steered in the right direction, or they’re asking to be the next candidate for the Darwin Awards.

This is turning into eTundra’s HOW-TO board that I scoffed at several years ago.

 

I come here to help out other technicians.

 

 

From questions like THIS one, in addition to this forum’s automated filter algorithms preventing my rather heartfelt write up I’d composed for posting…for other techs to chime in on to hearken back to what a successful mom-and-pop business was like to work for years ago…BEFORE a corporate acquisition ran it into the ground – has got me to thinking that I’m JUST ABOUT OUT OF HERE.

[fixbear]

Yea, I probably should not have covered it so completely.  But I figured he just wasted $300 on parts and was going to do more without a understanding of how the machine is built.  His time and money would have been better spent finding a qualified tech that will work at a reasonable price.  This trade has a lot of gougers out there that just shotgun parts at machines and never solve problems.  It’s how I secured most of my permanent customers.

[fixbear]

Oh, yea,  I wrote it because I have seen so many “techs”  over the years that have no idea how to properly test one. I realize that we have owner/operators on, but every once in a while we get someone in the trade that needs a bit of help.