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Jandy Lx400 Heater Problems - Won't Light


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I have a customer with a similar heater. Anyone know where the other end of the air switch hose goes?

Scott

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I have a customer with a similar heater. Anyone know where the other end of the air switch hose goes?

Scott

Scott, The hose should go from the switch, to a point on the vent (after the blower). Im guessing you know that, so i must be missing something.

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After the blower would imply it's looking for positive pressure, not negative (suction). I can't find the nipple the end plugs into. The air hose isn't shown in the book. One end goes in the switch, no problem there. The other end of the hose is hanging in the air with no obvious home that I can see.

Scott

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You may have to get into the heaters blower area and look around the sheet metal enclosure of the blowers' fan. I thought the nipple stuck out of the blowers round enclosure. Have to admit, i haven't worked on one of these in about a year, so the memory is a little foggy(side effect of age i guess).

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  • 2 months later...

My experience with the LAARS LX400P:

My heater (wired for 240vac) was intermittent and eventually would not light at all. It would give me an AGS fault indicator. I finally came by the LX Low NOx manual and was able to do some troubleshooting.

I tested the safety circuits and they checked OK.

Blower Pressure

Gas Valve control voltage

Ignition Control

Water Pressure

28vac was being applied to the LP gas valve at the appropriate time and the igniter lit up, but there was no gas flow.

I have a 15kw generator that runs off a tee on the high pressure side of the regulator and the generator runs ok, so I knew there was sufficient LP supply. The LAARS regulator is located right beside the unit. The heater worked last year, so I'm thinking LP pressure is still ok (no changes in LP plumbing).

I assumed the valve was bad, but was hesitant to replace it due to cost and by forum comments saying that they never went out.

There are no service resources within a reasonable distance, so I was doing this myself. I am a retired electronics engineer, so I'm comfortable with test equipment and circuitry.

I'm saying all this to say that, out of desperation, I finally fired the system up again while monitoring the valve voltage. I waited until the purge cycle ended and the request for gas began. Then I took a solid state electronic service tool (small hammer) and tapped the side of the gas valve. Bingo! I got gas flow, the heater ignited and ran. I assume the actuator in the valve is sticking.

I now feel that I'm justified in purchasing a replacement valve.

I just wanted everyone to know that the valve does fail, although it probably is a rare occurrence. I can now add it to the many infallible devices that I've had to replace during my career.

My thanks to the members of this forum and particularly of this thread. I'm impressed by the quantity and quality of the helpful responses here. The moderator and the contributors should be proud of the service they’re performing. It has truly been an educational experience.

Jack

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Sorry if we tried to steer you away from the gas valve. Statement should have been: "they don't go out often".

Tis OK. It just led to a little more checking to verify that it was the problem. I feel more comfortable placing the order now. So all is good.

Jack

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I have a Jandy LX400 Natural Gas Heater. It's almost 2 years old. I have never been able to get the thing to turn on. The heater lights for a few seconds and then shuts off, it then tries again and the same. It goes through three cycles of this and then gives me an error "AGS". The manually says it's not enough gas pressure.

I had two Jandy service guys come out, both from the same place. Neither seemed knowledgable to me. I actually felt I knew more about troubleshooting the problem than they did.

The first guy told me it was that supply line was too small. When I told him I had a knew 1.25" line put in, which is what the manually specified, he said it's probably clogged with plumbers putty. I asked him if he could measure the WC pressure but he said he didn't have his gauge. He left without fixing the problem since it was a "plumbing issue".

To rule his conclusion out, I bypassed the new line and ran a temp line out of 2" PVC from my gas meter to the heater. Same thing... three cycles, no heat. I then made my own gas manometer to measure the level of water columns at the heater's gas valve and then after, before it enters the manifold. With the 2" PVC, I get more than enough pressure at the gas valve. However, I don't get enough pressure after the valve. This is the same with the 1.25" supply line. I took the valve to see if there was anything clogging and found nothing.

I then called the second guy. He comes out, takes a look around, listens to my troubleshooting and concludes that my Gas Meter is undersized. I say OK, easy enough. So I call the Gas Company, they ask me for the size of the meter. I give them the model and they say it's largest residential meter I can get.

I think it's the gas valve on the heater that's faulty. The Jandy reps say "Oh those things never go bad". I can pick one up for $175 which I probably will do just to rule it out. Maybe I'll get lucky and it will fix the problem. Who knows.

So that's where I am today. This has been a royal pain in my @$$ so it's been really easy to ignore the problem. I want to be able to heat my spa this summer so I have decided to get this issue resolved once and for all, even if it means shelling out another $2000 for a new heater.

Any help you guys can give me would be much appreciated.

Gas heater failures! here are two primary reasons for failure to maitain heat. Number one. any leak in the heat exchanger will expand when the flame is ignighted, the resulting spew of water will fog up and put out the flame, the heater will cycle, and light over, and over again. Number two, The heat exchanger is so clogged full of carbon dust that the exhaust temp exceds the limit of the exhaust temp probe and shuts the heater down. Time to check the heat exchanger for leaks and or carbon build up.

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Gas heater failures! here are two primary reasons for failure to maitain heat. Number one. any leak in the heat exchanger will expand when the flame is ignighted, the resulting spew of water will fog up and put out the flame, the heater will cycle, and light over, and over again. Number two, The heat exchanger is so clogged full of carbon dust that the exhaust temp exceds the limit of the exhaust temp probe and shuts the heater down. Time to check the heat exchanger for leaks and or carbon build up.

Question:

How does a sooted, and or leaking heater cause a gas valve to stick?

You should read the entire post, not just the first post, before you remark. Otherwise you sound as if you didn't bother to read the thread, and your reply is not of worth, and irrelevant.

It sounds like you have alot of sooted up heaters that have pin hole leaks on your route.

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  • 1 month later...

I too have had significant issues with a used Jandy LT400 lighting intermittantly and getting numerous AGS faults. I have replaced the meter with a larger one (no cost PG&E). That improved things, but did not solve my problem. Thanks to this thread, I now have several things to check on the manifold and flame sensor before I drop the $$ on replacing the line between the meter and the unit. Thank you for the high quality advice, flow charts and photos.

John

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I too have had significant issues with a used Jandy LT400 lighting intermittantly and getting numerous AGS faults. I have replaced the meter with a larger one (no cost PG&E). That improved things, but did not solve my problem. Thanks to this thread, I now have several things to check on the manifold and flame sensor before I drop the $$ on replacing the line between the meter and the unit. Thank you for the high quality advice, flow charts and photos.

John

John, You can check the flame sensing rod for soot, or check the burner jet that is directly under the pilot. This will require you to remove the burner tray. Or a sooted heat ex-changer may give the same symptom. If you don't feel comfortable doing this, maybe leave it to a pool pro.

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<!--quoteo(post=50669:date=Mar 14 2008, 06:22 PM:name=drip)--><div class='quotetop'>QUOTE(drip @ Mar 14 2008, 06:22 PM) <a href="index.php?act=findpost&pid=50669"><{POST_SNAPBACK}></a></div><div class='quotemain'><!--quotec-->Hi, is the heater actually lighting? do you feel heat from the vent area? If it is and then it sounds like your flame sensor is not working or and this is more likely, the gas orifice feeding the burner that the flame sensor is over is plugged, spiders love to build webs in there, you sound mechanically inclined so I won't go into how to clean them. Also you might try adjusting it to get into the flame better.

If it is not lighting and just cycling 3 times then AGS then it sounds like your igniter is bad, to test just pull it out just your gas valve off and try to fire the heater, it should glow red hot.

FYI some of the most frustrating problems with heaters when you can't find a bad part is those clogged orifices. Oh, and gas valves very rarely go bad.

If none of this works and someone else can't give you a solution I have a Jandy LX factory troubleshooting flow chart that I'm sure could help you get it figured out, the best I know how to do is to scan it into my comp and email it to you. Let me know.<!--QuoteEnd--></div><!--QuoteEEnd-->

Drip,

Thanks for the reply. I will try the things you suggested but I doubt it's a clog. Keep in mind, I've had this problem since the heater was taken out of the box and installed. Also, I do feel heat coming from the manifold so it is lighting. The problem is the valve shuts off after a couple of seconds; I can actually hear when the valve closes. No matter, I will check everything for debris or spiders/webs, etc. just to rule those things out.

Hey, that would be great if you can send me that troubleshooting guide. Please email it to me at anonymouscuban@yahoo.com.

I will keep you guys posted on what happens after I try the different things you all suggested and also after I replace the valve.

I have the exact same issue.....Starts 3 times and goes to AGS....Same issues with Jandy and Gas company....Can you email the troubleshooting guide you recieved? sweede58@yahoo.com

Thanks

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  • 7 months later...

Brand spanking new Jandy Zodiac LXi heater, 400 k BTU/hr will not light. Help!

On initial system start up the pool company guy said “didn’t anyone tell you that you needed to increase the size of the gas meter?”.

My current home has 3 X 100k BTU furnaces that all run simultaneously in the winter, plus a 6 burner gas range to I have done some troubleshooting while I wait for the gas company to install the next size larger meter (in about 3 weeks).

Here’s what I can tell you – FIRST – I am mechanically inclined although my degree in chemical engineering may reverse any advantage that may have due to hubris.

Gas supply pressure to the heater is 7.5 inches water column, measured at the crud trap and also at the test port on the inlet side of the gas valve.

Heater is correctly wired at 240 VAC supply.

Water flow valve works correctly (open circuit with no flow, closed circuit with flow).

Igniter glows red when system attempts to fire (I opened manifold box, took out igniter and watched to see what happened with gas supply “off”, of course…. I did notice that the hex nuts on the igniter were just barely finger tight – really no torque on them at all. I applied a careful amount of torque when reinstalling the igniter.)

There are no obvious spider nests or other insects that have taken up residence in the burner throats.

Gas valve works; solenoid clicks open about 30 or so seconds into the firing sequence, stays open for 6 or 7 seconds, then closes. System cycles 3 times before shut down as it is supposed to do.

Gas pressure at burner manifold is 2.5 inches water column when the gas valve opens – exactly what the sticker on the manifold says it is supposed to be.

Burner throat pressure is 1.0 inches water column when forced draft fan is running.

About the only thing I did not yet check carefully are the wires to/from the flame rollout sensor – reading some other posts here I see someone had a problem where the wires to this sensor were cracked and correcting that got the heater to fire.

Any thoughts or suggestions greatly appreciated !

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Describe the line diameters and lengths from the meter to the heater.

How many cubic feet can your gas meter supply?

Have you checked the orifices of the gas manifold that feeds the burners?

Scott

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I saw that but it only answers the next set of questions I was going to ask. Have to go step by step.

Scott

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Describe the line diameters and lengths from the meter to the heater.

How many cubic feet can your gas meter supply?

Have you checked the orifices of the gas manifold that feeds the burners?

Scott

Hi Scott....... line from the meter to the heater (hey, that rhymes!) is 1.5 inch diameter yellow polysomething (probably polyurethane I would think), and about 15 to 20 linear feet if I could the bends. It is pretty close to the heater in other words.

I did visually inspect the gas orifices, no obvious sign of being clogged. If there is something else I should be looking for please let me know. There is an orifice in the gas valve and it has a "NG" sticker on it for natural gas.

The gas meter says "225" on it, PSE&G will come replace it with a larger one in 3 weeks. I am suspicious that the pressure setting on the current meter is just at 7.5 inches of water, and the heater may want slightly higher than that (despite the sticker on the heater manifold cover that says it requires 2.5 inches water column.... which is exactly what I measured when the unit attempted to light).

regards

Steve

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This is a test. I tried to write about 500 words here yesterday, but it looks like I did something wrong and it did not post........ So if this works I'll enter it again

Here is your post...

http://www.poolspafo...ndpost&p=151938

Thank you Pool Clown, apparently there are some nuances to navigating this place that I need to learn ! I will go take the cover off the burner box again and look more closely at the burner directly beneath the igniter to be absolutely sure it is not clogged in some way.

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The gas meter says "225" on it, PSE&G will come replace it with a larger one in 3 weeks.

That is part, if not all the problem. Your current meter is rated to 225K btus. Your pool heater alone requires 400K.

I am suspicious that the pressure setting on the current meter is just at 7.5 inches of water, and the heater may want slightly higher than that (despite the sticker on the heater manifold cover that says it requires 2.5 inches water column.... which is exactly what I measured when the unit attempted to light).

What your looking for on the sticker is the minimum inlet pressure in WC. Your water column cannot fall below that number while the heater is firing.

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The gas meter says "225" on it, PSE&G will come replace it with a larger one in 3 weeks.

That is part, if not all the problem. Your current meter is rated to 225K btus. Your pool heater alone requires 400K.

I am suspicious that the pressure setting on the current meter is just at 7.5 inches of water, and the heater may want slightly higher than that (despite the sticker on the heater manifold cover that says it requires 2.5 inches water column.... which is exactly what I measured when the unit attempted to light).

What your looking for on the sticker is the minimum inlet pressure in WC. Your water column cannot fall below that number while the heater is firing.

Well, the inlet pressure when the heater attempts to fire is equal to what the sticker says it is supposed to be..... 2.5 inches water column. At this point I will wait for the new gas meter to see if that really is the limitation. As I posted earlier..... current home has 3 X 100k BTU furnaces, + 80k BTU water heater, + kitchen gas range that at certain times in the winter all fire concurrently without any apparent problem. If there is a way I can upload video here, you could see what I measured with my rudimentary manometer.......

Anyway I do appreciate the input and comments!

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The gas meter can only put out 225 cubic feet and the heater needs close to 400. It may take a bit to get the pressure to drop below, but it will. Add an appliance to the mix and things get worse, as you can imagine.

Scott

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Symptoms: Jandy LX250 will start, gas switch will click, fire up and exhaust heat for about 10 seconds, then shut down. The system does this twice, and then the AGS light comes on.

Things I've tried: Checked the connections on both ends of the flame sensor, cleaned the flame sensor with emry cloth (already looked clean). Stuck a paper clip in each of the brass nozzles to see if there were any spider eggs (none that I could tell).

I have a craftsman multimeter:

http://www.sears.com/craftsman-digital-multimeter-with-ac-voltage-detector/p-03482146000P?prdNo=8&blockNo=8&blockType=G8

but I'm a noob when it comes to using a multimeter, like even choosing which of the three ports I plug my red and black wire into, and which red/black wire should be touching each terminal lead on the test subject.

Any help would be great, I suspect the fenwal ignition control box. After a lot of reading, I think I'm supposed to test for 24v on some of the connections on the fenwal box such as the TH and VAL. A new fenwal is $200. I don't really want to just be purchasing parts at random to replace without knowing much.

Any initial guesses or troubleshooting steps for me?

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