Jandy Lx250 Problem

[sooneraia]

OK. I know there is a lengthy thread on the LX400, and I have read it, very good information, I will print out the trouble shooting guide. My problem though, is a little different, so I thought I would start a new one. (I am new to this board so if in the future the admins would prefer I put my questions with other similar threads I will). My 8 year old LX250 will not fire. Our pool has only been opened a few weeks, and we fired the heater up a couple of times already this year, so this recent problem has me wondering. Simply put, when I turn it on, the fan begins to run (normal), but the "HEATING" light that normally flashes after 30 seconds or so, does not come on. She will run for a couple of minutes, fan continues to blow, then the AGS indicator comes on, she shuts off. We had a storm in between the last firing and this one, lost a tree adjacent to the pool / gas line, so I thought maybe we had diminished pressure. So I loosened my gas line (between the shut off and the heater) and could smell gas, so I assume my pressure is fine (I don't have any testing equipment to determine the pressure). I pulled the gas valve assembly off, shook it out, re-installed it, tried again, and the exact same sequence happened - fan - no "HEATING" flash - shuts off. In other years my main problems were bad HSI's, I replaced those. This one is a little different, hence the request. I know it's a holiday weekend, but if anyone in on-line and can help, it would be much appreciated.

[AFiremanFirst]

glad that you did your hsi!!! Good!!! I had a similar problem with my pentair heater, pentair suggested I get a new heater, appartenly even pentair is not proud of the product I own, but I'm a little hard headed. With a good volt/ohm meter ($15) and a good Jandy rep (on the phone), you should be able to get to the bottom of it! I'm leaning toward your fenwal, or electronic ignition system. But I also had to replace my blower fan flow switch. There are many components that must be working for the heater to fire. It must be able to detect the blower is blowing, that water is flowing and that the gas is on. Don't give up, and don't rush it. It's one weekend, there will be more!

[sooneraia]

glad that you did your hsi!!! Good!!! I had a similar problem with my pentair heater, pentair suggested I get a new heater, appartenly even pentair is not proud of the product I own, but I'm a little hard headed. With a good volt/ohm meter ($15) and a good Jandy rep (on the phone), you should be able to get to the bottom of it! I'm leaning toward your fenwal, or electronic ignition system. But I also had to replace my blower fan flow switch. There are many components that must be working for the heater to fire. It must be able to detect the blower is blowing, that water is flowing and that the gas is on. Don't give up, and don't rush it. It's one weekend, there will be more!

Appreciate the response. I was hoping I would not have to contact Jandy, but might have to. I happen to live in a fairly small town, and we are void of qualified pool heater repair people, as well as parts houses. I would sure like to be fairly confident in my diagnosis before I order any parts. I will keep plugging along on my end and keep those interested informed.

[Bugman1400]

glad that you did your hsi!!! Good!!! I had a similar problem with my pentair heater, pentair suggested I get a new heater, appartenly even pentair is not proud of the product I own, but I'm a little hard headed. With a good volt/ohm meter ($15) and a good Jandy rep (on the phone), you should be able to get to the bottom of it! I'm leaning toward your fenwal, or electronic ignition system. But I also had to replace my blower fan flow switch. There are many components that must be working for the heater to fire. It must be able to detect the blower is blowing, that water is flowing and that the gas is on. Don't give up, and don't rush it. It's one weekend, there will be more!

Appreciate the response. I was hoping I would not have to contact Jandy, but might have to. I happen to live in a fairly small town, and we are void of qualified pool heater repair people, as well as parts houses. I would sure like to be fairly confident in my diagnosis before I order any parts. I will keep plugging along on my end and keep those interested informed.

I don't disagree that it could be the Fenwal, but there are plenty of other related things to check first. First and foremost, if the glowbar to the HSI glows then that is not it. You should be able to see the glowbar at or near the burner. Another obvious thing to look for is the "click" of the gas valve. If you hear the "click" then that is not the problem either (more than likely). Like you, I have also tested for gas by loosening the union near the shutoff valve. However, you should also be able to hear the gas escaping with a decent amount of volume. Also, check your flame sensor. It should be located near the glowbar. Take a piece of sandpaper and make a few passes over the probe. So, report back on the following:

1.)Does the glowbar glow?

2.)Do you hear the gas valve "click"?

3.)Did you clean the flame sensor?

If you don't know what the hell I'm talking about on any of these questions then either read more or call a pool tech.

[sooneraia]

To answer the questions,

1. The glow bar does not glow.

2. I do not thonk I hear the gas valve click. My blower is getting loud now, so the "click" is harder to detect.

3. I have not cleaned the flame sensor. Since the glow bar is not lighting, I did not think the flame sensor would matter (no flame).

The thing is, when I start it up, the blower begins, the "HEATING" light does not flash. So it seems like nothing would be "heating", ie. the glow bar. I did look down at the burner area and did not see any glow. I will give them allanother shot tomorrow, but if there is anything else you can think of prior to that, please post. Thanks.

[Pool Clown]

If you put your fingers on the underside of the gas valve, you should be able to feel it click open. If the gas valve opens then all the safety switches have been satisfied. If you do, see if you smell any raw gas coming out of the blower vent. Be quick tho, it will just be a whiff, then you may, or may not be able to feel the gas valve click shut. If you catch a whiff of gas, then the HSI has failed (again). You can also use your ohm meter to measure resistance of the HSI. If you look at the other thread, the resistance value is posted. It's the same for all the (Jandy) positive vent heaters.

[sooneraia]

I tried to start the heater this morning. First off, turned it on, the blower began running, I felt the gas meter and put my ear by it - I did not feel or hear the "click". I watched for any glow on the ignitor (glow bar)and saw none. The thing that as different this time was, the blower only ran for 30-45 seconds before it shut down and when it shut down there was no "error message" on the console. Normally (at least yesterday), the blower would run for at least 2-3 minutes (I know it is supposed to try to cycle three times before it shuts down), then shut down and give me the AGS error.

So in summary, no glow bar glow, no "click" at the gas valve and I still have not cleaned the flame sensor. Also, I did not detect any hint of gas smell when trying this process. If a safety switch is bad (or needs to be reset), any ideas on which would be the first to look at? Thanks again for all the ideas.

[Pool Clown]

My blower is getting loud now, so the "click" is harder to detect.

When the bearings go out on the blower(noise), the blower has to work harder to spin the blower. This may keep the blower form reaching it's predetermined speed for closing the air flow switch, therefore, the air flow switch may not be getting satisfied, and not allowing firing of the heater.

Note: I have had heaters do this, and could not tell that the blower wasn't moving enough air, till i replaced it. Then i could tell by how much more air the new blower moved, it was very apparent that the old blower was not moving nearly enough air.

I would check the air flow switch, while the blower is running, to see if the blowers volume is enough to close that switch.

[Bugman1400]

I tried to start the heater this morning. First off, turned it on, the blower began running, I felt the gas meter and put my ear by it - I did not feel or hear the "click". I watched for any glow on the ignitor (glow bar)and saw none. The thing that as different this time was, the blower only ran for 30-45 seconds before it shut down and when it shut down there was no "error message" on the console. Normally (at least yesterday), the blower would run for at least 2-3 minutes (I know it is supposed to try to cycle three times before it shuts down), then shut down and give me the AGS error.

So in summary, no glow bar glow, no "click" at the gas valve and I still have not cleaned the flame sensor. Also, I did not detect any hint of gas smell when trying this process. If a safety switch is bad (or needs to be reset), any ideas on which would be the first to look at? Thanks again for all the ideas.

The glow bar should glow way before the gas valve "click". So, if no glow then you need to check the reason for the no glow. If you have a voltmeter, you could check the voltage to the glow bar from the Fenwal. If you have voltage then the glow bar is broke. If you do not have voltage then the "safety circuit" (my term) is open. The "safety circuit" will consist of the blower switch and temp switches.

So, thing to check:

1.)Does my glow bar have voltage from the Fenwal? Check for voltage while the blower is on. I'll say the obvious....please be careful!

[sooneraia]

Thanks for the tips, I will check those out. The "safety circuit" - blower switches and temp (high/low)switches being open, how do you check this? Voltage? I don't see and "re-set" buttons. Do I have to pull the high/low temp switches to inspect them, or is this a "voltage" check thing. Also, a stupid question, when I check some of the components (I am using the trouble shooting guide in a previous thread), when it says to "check for 24VAC", does that mean I need to have 24VAC show up on my meter? Or am I merely testing to see if some current is flowing, not necessarily 24VAC. Don't worry, I won't blow myself up......................

Also, what would the voltage be at the glow bar - 120? I checked mine and it was at 30.

[Bugman1400]

Thanks for the tips, I will check those out. The "safety circuit" - blower switches and temp (high/low)switches being open, how do you check this? Voltage? I don't see and "re-set" buttons. Do I have to pull the high/low temp switches to inspect them, or is this a "voltage" check thing. Also, a stupid question, when I check some of the components (I am using the trouble shooting guide in a previous thread), when it says to "check for 24VAC", does that mean I need to have 24VAC show up on my meter? Or am I merely testing to see if some current is flowing, not necessarily 24VAC. Don't worry, I won't blow myself up......................

Also, what would the voltage be at the glow bar - 120? I checked mine and it was at 30.

When you check for 24VAC, you put one lead to ground and use the other lead to check at each of the points in the "saftey chain". The current draw thru this circuit will be very small.

If your glow bar voltage is 30V then it doesn't sound like the Fenwal is sending the 120V signal to the glow bar to ignite. You'll have to figure out why. Check Terminal W, see below. Also, what is your Fenwal Model#?

Call For Heat

35-65 & 35-66 without Full-time power (r terminal):

When a call for heat is received from the thermostat supplying 24

volts to the W terminal, the control will perform a self-check routine,

flash the diagnostic LED for a second and begin the safety timing

sequence. After an optional "pre-purge" period, the hot

surface ignitor is energized for a heat-up period, followed by the

gas valve for the "trial for ignition" (TFI) period.

Did you find the flame sensor and give it a sanding?

[sooneraia]

Thanks for the tips, I will check those out. The "safety circuit" - blower switches and temp (high/low)switches being open, how do you check this? Voltage? I don't see and "re-set" buttons. Do I have to pull the high/low temp switches to inspect them, or is this a "voltage" check thing. Also, a stupid question, when I check some of the components (I am using the trouble shooting guide in a previous thread), when it says to "check for 24VAC", does that mean I need to have 24VAC show up on my meter? Or am I merely testing to see if some current is flowing, not necessarily 24VAC. Don't worry, I won't blow myself up......................

Also, what would the voltage be at the glow bar - 120? I checked mine and it was at 30.

When you check for 24VAC, you put one lead to ground and use the other lead to check at each of the points in the "saftey chain". The current draw thru this circuit will be very small.

If your glow bar voltage is 30V then it doesn't sound like the Fenwal is sending the 120V signal to the glow bar to ignite. You'll have to figure out why. Check Terminal W, see below. Also, what is your Fenwal Model#?

Call For Heat

35-65 & 35-66 without Full-time power (r terminal):

When a call for heat is received from the thermostat supplying 24

volts to the W terminal, the control will perform a self-check routine,

flash the diagnostic LED for a second and begin the safety timing

sequence. After an optional "pre-purge" period, the hot

surface ignitor is energized for a heat-up period, followed by the

gas valve for the "trial for ignition" (TFI) period.

Did you find the flame sensor and give it a sanding?

OK, here we go. First off, I did not find a Terminal W on my Fenwall. The numbers on it are Catalog #05-332161-103; Teledyne Laars E0180400; there is also a 0230F stamped on it.

Regarding the flame sensor, the screw that holds the sensor / plate is trashed (corroded / stripped), so it wil take a little work to get it out. I will continue to work on that. Thanks for the continued efforts.

I will try to post a picture of my Fenwall if I can.

[Bugman1400]

Thanks for the tips, I will check those out. The "safety circuit" - blower switches and temp (high/low)switches being open, how do you check this? Voltage? I don't see and "re-set" buttons. Do I have to pull the high/low temp switches to inspect them, or is this a "voltage" check thing. Also, a stupid question, when I check some of the components (I am using the trouble shooting guide in a previous thread), when it says to "check for 24VAC", does that mean I need to have 24VAC show up on my meter? Or am I merely testing to see if some current is flowing, not necessarily 24VAC. Don't worry, I won't blow myself up......................

Also, what would the voltage be at the glow bar - 120? I checked mine and it was at 30.

When you check for 24VAC, you put one lead to ground and use the other lead to check at each of the points in the "saftey chain". The current draw thru this circuit will be very small.

If your glow bar voltage is 30V then it doesn't sound like the Fenwal is sending the 120V signal to the glow bar to ignite. You'll have to figure out why. Check Terminal W, see below. Also, what is your Fenwal Model#?

Call For Heat

35-65 & 35-66 without Full-time power (r terminal):

When a call for heat is received from the thermostat supplying 24

volts to the W terminal, the control will perform a self-check routine,

flash the diagnostic LED for a second and begin the safety timing

sequence. After an optional "pre-purge" period, the hot

surface ignitor is energized for a heat-up period, followed by the

gas valve for the "trial for ignition" (TFI) period.

Did you find the flame sensor and give it a sanding?

OK, here we go. First off, I did not find a Terminal W on my Fenwall. The numbers on it are Catalog #05-332161-103; Teledyne Laars E0180400; there is also a 0230F stamped on it.

Regarding the flame sensor, the screw that holds the sensor / plate is trashed (corroded / stripped), so it wil take a little work to get it out. I will continue to work on that. Thanks for the continued efforts.

I will try to post a picture of my Fenwall if I can.

No need.....the catalog# will do....Google does wonders.

The FS terminal is the Flame Sensor.

The F1 & F2 terminals are for the exhaust (inducer) fan.

The VAL is for the gas valve.

The IND is the input at the end of the "saftey chain".

The TH is the input for the Thermostat (the call for heat).

The IGN goes to one side of the glow bar.

The IGN/120 goes to the other side of the glow bar.

See Figure 4a on Page 3 in the link below.

Fenwal Manual

Fenwal Photo

So check for 24VAC voltage at TH after the inducer fan kicks on. Put one lead on TH and the other lead to ground. If you get around 24VAC then most likely it is the Flame Sensor. If you do not get the 24VAC then you have a break in your "safety chain".

Good Luck and report back.

[sooneraia]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

[Bugman1400]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

[sooneraia]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

Not yet, I will get to that right after lunch. Honestly, I wanted to make sure I was testing the TH condition correctly before I pulled the sensor. What am I testing for with the flame sensor? I need to sand it a bit right? Do I need to see if we have 24vac thru that item as well?

Just a question, which comes first - the ignitor glow then the flame sensor "senses" the flame and tells the gas it's OK? Or does the flame sensor need to sense something from the ignitor before it (the flame sensor) allows the ignitor to glow.

[Bugman1400]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

Not yet, I will get to that right after lunch. Honestly, I wanted to make sure I was testing the TH condition correctly before I pulled the sensor. What am I testing for with the flame sensor? I need to sand it a bit right? Do I need to see if we have 24vac thru that item as well?

Just a question, which comes first - the ignitor glow then the flame sensor "senses" the flame and tells the gas it's OK? Or does the flame sensor need to sense something from the ignitor before it (the flame sensor) allows the ignitor to glow.

I don't think the flame sensor has the 24VAC control voltage. It works off a resistance value. I think the Fenwal checks the flame sensor beforehand to confirm the abscence of the flame. So, if the flame sensor has crud on it and the Fenwal thinks there is already a flame....why would it initiate another ignition sequence. Obviously, there are ways to fool the Fenwal into thinking that there is no flame, but I'm not sure if the resistance is supposed to be high or low for the abscence of flame condition.

Report back your findings after the sanding.

[sooneraia]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

Not yet, I will get to that right after lunch. Honestly, I wanted to make sure I was testing the TH condition correctly before I pulled the sensor. What am I testing for with the flame sensor? I need to sand it a bit right? Do I need to see if we have 24vac thru that item as well?

Just a question, which comes first - the ignitor glow then the flame sensor "senses" the flame and tells the gas it's OK? Or does the flame sensor need to sense something from the ignitor before it (the flame sensor) allows the ignitor to glow.

I don't think the flame sensor has the 24VAC control voltage. It works off a resistance value. I think the Fenwal checks the flame sensor beforehand to confirm the abscence of the flame. So, if the flame sensor has crud on it and the Fenwal thinks there is already a flame....why would it initiate another ignition sequence. Obviously, there are ways to fool the Fenwal into thinking that there is no flame, but I'm not sure if the resistance is supposed to be high or low for the abscence of flame condition.

Report back your findings after the sanding.

OK, I removed the flame sensor, it had what appeared to be a little rusty surface, sanded it. In the midst of getting it out, the wire pulled away from the harness to the actual flame sensor rod. So I removed the coupling, stripped back 1/4" of wire and re-attached it - good as new. Plugged it back in, started the heater and after about 10-15 seconds I heard a "poof", - crap. Shut it down and pulled the hot surface ignitor and on one side where the actual ceramic heating surface attaches to the plastic looking case - it's black (the other side is white) and appears to have blown or shorted. So, I know I will be buying a new HSI. I just hope when I attach the new HSI I don't have it blow like this one did. Kind of strange. Thoughts? If I can get my hands on a new HSI this afternoon I will and give it a whirl.

[Bugman1400]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

Not yet, I will get to that right after lunch. Honestly, I wanted to make sure I was testing the TH condition correctly before I pulled the sensor. What am I testing for with the flame sensor? I need to sand it a bit right? Do I need to see if we have 24vac thru that item as well?

Just a question, which comes first - the ignitor glow then the flame sensor "senses" the flame and tells the gas it's OK? Or does the flame sensor need to sense something from the ignitor before it (the flame sensor) allows the ignitor to glow.

I don't think the flame sensor has the 24VAC control voltage. It works off a resistance value. I think the Fenwal checks the flame sensor beforehand to confirm the abscence of the flame. So, if the flame sensor has crud on it and the Fenwal thinks there is already a flame....why would it initiate another ignition sequence. Obviously, there are ways to fool the Fenwal into thinking that there is no flame, but I'm not sure if the resistance is supposed to be high or low for the abscence of flame condition.

Report back your findings after the sanding.

OK, I removed the flame sensor, it had what appeared to be a little rusty surface, sanded it. In the midst of getting it out, the wire pulled away from the harness to the actual flame sensor rod. So I removed the coupling, stripped back 1/4" of wire and re-attached it - good as new. Plugged it back in, started the heater and after about 10-15 seconds I heard a "poof", - crap. Shut it down and pulled the hot surface ignitor and on one side where the actual ceramic heating surface attaches to the plastic looking case - it's black (the other side is white) and appears to have blown or shorted. So, I know I will be buying a new HSI. I just hope when I attach the new HSI I don't have it blow like this one did. Kind of strange. Thoughts? If I can get my hands on a new HSI this afternoon I will and give it a whirl.

Are you saying that the wires to the glow bar burned off? If the glow bar is bad it will usually have a gap it in. It is also possible that a bug, some crud, or something was on the glow bar as it started to glow and ignited.....I've seen that happen.....but the glow bar will still be good and will continue to glow.

[sooneraia]

OK, so here is what I did. I disconnected the TH wire at the Fenwall, started the heater (blower running)and checked voltage. I placed one lead into the end of the TH wire (not at the TH connection on the Fenwall), and the other lead to ground, I came up with an average reading of 26.33 VAC. (I wanted to make sure that I am supposed to test the TH wire that connects to the Fenwall and not the TH connection on the Fenwall).

You did it right. So, the 26.33VAC tells you that the "safety chain" has no broken links. About the only thing left is the flame sensor. Did you get to that yet?

Not yet, I will get to that right after lunch. Honestly, I wanted to make sure I was testing the TH condition correctly before I pulled the sensor. What am I testing for with the flame sensor? I need to sand it a bit right? Do I need to see if we have 24vac thru that item as well?

Just a question, which comes first - the ignitor glow then the flame sensor "senses" the flame and tells the gas it's OK? Or does the flame sensor need to sense something from the ignitor before it (the flame sensor) allows the ignitor to glow.

I don't think the flame sensor has the 24VAC control voltage. It works off a resistance value. I think the Fenwal checks the flame sensor beforehand to confirm the abscence of the flame. So, if the flame sensor has crud on it and the Fenwal thinks there is already a flame....why would it initiate another ignition sequence. Obviously, there are ways to fool the Fenwal into thinking that there is no flame, but I'm not sure if the resistance is supposed to be high or low for the abscence of flame condition.

Report back your findings after the sanding.

OK, I removed the flame sensor, it had what appeared to be a little rusty surface, sanded it. In the midst of getting it out, the wire pulled away from the harness to the actual flame sensor rod. So I removed the coupling, stripped back 1/4" of wire and re-attached it - good as new. Plugged it back in, started the heater and after about 10-15 seconds I heard a "poof", - crap. Shut it down and pulled the hot surface ignitor and on one side where the actual ceramic heating surface attaches to the plastic looking case - it's black (the other side is white) and appears to have blown or shorted. So, I know I will be buying a new HSI. I just hope when I attach the new HSI I don't have it blow like this one did. Kind of strange. Thoughts? If I can get my hands on a new HSI this afternoon I will and give it a whirl.

Are you saying that the wires to the glow bar burned off? If the glow bar is bad it will usually have a gap it in. It is also possible that a bug, some crud, or something was on the glow bar as it started to glow and ignited.....I've seen that happen.....but the glow bar will still be good and will continue to glow.

I was able to pick up a new HSI (glow bar) this afternoon, so I may try to hook it up this evening. I have just never had that kind of thing happen before. The wires to the glow bar did not burn off, there is no gap in the element, but that one is toast now anyway as I have touched the element anyway. I am just kind of paranoid about hooking up the new HSI (glow bar), hoping it doesn't "short" out. If it does, I will have a whole new set of issues to deal with....................

As always, thanks for assisting me in this adventure.

[Pool Clown]

I think the Fenwal checks the flame sensor beforehand to confirm the abscence of the flame. So, if the flame sensor has crud on it and the Fenwal thinks there is already a flame....why would it initiate another ignition sequence. Obviously, there are ways to fool the Fenwal into thinking that there is no flame, but I'm not sure if the resistance is supposed to be high or low for the abscence of flame condition.

You have it backwards. Flame rectifier proves, or confirms that there is flame after ignition. As long as flame is proven, gas valve remains open till set point is reached. Bad or sooted flame proving rod will allow ignition for about 5 seconds before it tells the gas valve no proof, due to the interference, or no flame, and closes gas valve.

[cp1]

Hello all, great forum ! I also have an LX250 and have the exact same problem. I opened her up tonight and these two white wires were just hanging there, The must have come loose from somewhere. Can someone advise where they go?

Thanks ... I have attached pics.