Can anyone tell me how to replace the ignitor? The heater cycles 3 times trying to fire up but wont. I checked the continuity between the ignitor wires and there wasn't any. I'm assuming there should be. The two wires enter below one of the gas cones into the combustion chamber. I can't see the ignitor. This heater is 9 years old. Thanks in advance!
Jandy Laars LT400N Pool heater ignitor replacement
- Thread starter petes914
- Start date
Has no one ever replaced an ignitor in a Laars LT pool heater? Did I forget to describe something?
I don't work on these units but here is a site that has a exploded parts view of the heater and from looking at it it appears to be pretty easy to replace. Look at the diagram and part #44 is the ignitor. Probably has two screws holding it in place or a bracket with a screw or two.
http://www.poolpartsonline.com/p-22-jan ... lt400.aspx
http://www.poolpartsonline.com/p-22-jan ... lt400.aspx
Hi Paul,
Thanks for responding. I believe mine is a 2004 model. Its def different from that diagram. In my operators manual it looks like the ignitor is mounted on the back of the combustion chamber assembly which would require removing the whole assembly and gas manifold to get at it. It just seems like a ridiculous place to put it. I'm hoping someone responds who has actually replaced one, before I take it all apart. Especially if I don't have to. Lots of rusty parts. I'm afraid it is going to crumble to pieces.
Thanks for responding. I believe mine is a 2004 model. Its def different from that diagram. In my operators manual it looks like the ignitor is mounted on the back of the combustion chamber assembly which would require removing the whole assembly and gas manifold to get at it. It just seems like a ridiculous place to put it. I'm hoping someone responds who has actually replaced one, before I take it all apart. Especially if I don't have to. Lots of rusty parts. I'm afraid it is going to crumble to pieces.
Oh so maybe yours is a Low Nox model.
http://www.parts4heating.com/v/vspfiles ... r-NOX.html
Looks like you have to pull the burner tray out to get to it. If you see lots of rusted parts then there is a good chance it could fall apart. You could spray the nuts/bolts with WD40 or similar and then try to remove them. It's definitely a job for sure.
http://www.parts4heating.com/v/vspfiles ... r-NOX.html
Looks like you have to pull the burner tray out to get to it. If you see lots of rusted parts then there is a good chance it could fall apart. You could spray the nuts/bolts with WD40 or similar and then try to remove them. It's definitely a job for sure.
Yep. That's it. So that's what I have to do. Silly place to put something that eventually will need to be replaced. There's a sight glass but it too is all rusted and so dirty I can't see if the ignitor is glowing. I should get continuity across the wires leads though right? I'm not.
When you get it out, be sure not to touch the heating element portion of the new one. Finger oil will shorten the life of these
Ok, so replacing the ignitor was actually very easy. All I had to do was disconnect the gas manifold from the burner assembly, two nuts, and swing it out of the way, remove I think 8 screws holding in the burner assembly which were rusty but with some penetrating oil, they all came out no prob. Then just slide the burner tray out. The burners had some crud on the vents which I cleaned off with a wire brush. The ignitor was mounted on the back of one of the burners. Yes, one of the wires was broken. No rubber grommets on the sheet metal where the wires go through. Emptied out as much rust/crud from inside each burner, slid the assembly back in, swung the manifold back into place (have to check that the gas connection isn't leaking) and replaced the rusty screws with new ones. I also removed all the gas nozzles and cleaned out the cob webs. Anyway, I still have a problem. I replaced the ignitor as well as the flame sensor and still its not firing up. It cycles 3 times, fan seems to be functioning properly, I can smell gas so I know the gas valve is opening however, the ignitor isn't getting hot at all. I even disconnected the new ignitor and connected the old one outside the heater, after I was sure the gas dissipated (I did reconnect the broken wire and check for continuity) and the old one didn't get hot either. So I'm not getting any voltage to the ignitor. The Fenwal Ignition Control Module PN R0386800 is giving me an "Ignition Lockout" indication after the unit tries to start 3 times. As far as I can tell there hasn't been any ignition at all.
Any ideas? I know its not recommended, but can I fire this heater up with an open flame? Maybe one of those long grill lighters? Wife is pressuring me to get the pool heated up and I'm sure she would be ok with me potentially blowing myself up.
Any ideas? I know its not recommended, but can I fire this heater up with an open flame? Maybe one of those long grill lighters? Wife is pressuring me to get the pool heated up and I'm sure she would be ok with me potentially blowing myself up.
You need to verify that voltage is getting to the igniter. Trace the wires back to the board and test the voltage at the board with a volt/ohm meter. (should be 120 volts) If you have it there then there is another break in the wire somewhere. If not, then the board needs to be replaced.
I pulled the power supply board off and expected to see a lot of corrosion but it actually looked almost new. All the circuits seemed fine. I will check tonight though with multimeter. I'm wondering about the Fenwal Ignition Control Module. It has an LED Diagnostic indicator and a steady light indicated a faulty controller. I'm getting the three flashes which just indicates an Ignition Lockout. And again, this module, despite being 9 years old looks new as well.
petes914 said:
If I remember correctly, there is a resettable switch on behind the blower.
[attachment=0:24uv6xe4]ignition control module 7-15-13 (327x640).jpg[/attachment:24uv6xe4] So, I figured out why I wasn't getting any voltage at the new ignitor. This is the back of the ignition control module board. Looks like a spider made a nest and shorted out the board. Amazing how much $ insects can cost in pool repairs. I replaced the module, $150 and now the ignitor is working. However, the heater still isn't. When I turn on the heater the ignitor glows then a few seconds later I hear the gas valve open and the burners ignite. However, only for a second or two then the gas valve clicks off and the flames go out. It does this 3 times then goes into AGS mode (Automatic Gas shutoff) There seems to be more flame coming out the front of the burners then usual otherwise everything else seems normal. The fan seems to have a few different speeds. When the burners are igniting its at a very slow pulsing speed. After the burners go out the speed doubles. After the 3 attempts to start the fan blows hard for a minute or so then the AGS light glows and everything shuts down.
Any suggestions? How does the flame sensor work? Its new as well. Is it working when its sensing flame or working when its not sensing flame. I was thinking taking it out and holding a flame to it while the heater is igniting....good idea? Dumb idea?
I can also inform that the filter cartridges are pretty clogged. I have 4 - PA100N cartridges. I have pavers around my pool. I recently power washed the pavers and brushed new paver locker in between them. Very fine sand with cement in it which actually hardens like cement after spritzing with water. For the first week or so after doing this A LOT of this sand gets in the pool which gets sucked up and pretty much ruins my filters. Could there not be enough pressure causing the heater to not run? Although water is coming out of the returns, it seems at maybe half the pressure. I also replaced the pressure switch in the heater so that is new too. I definitely hear the gas valve opening and closing and it does in fact ignite during all three attempts however, it won't stay lit. Any ideas?
Any suggestions? How does the flame sensor work? Its new as well. Is it working when its sensing flame or working when its not sensing flame. I was thinking taking it out and holding a flame to it while the heater is igniting....good idea? Dumb idea?
I can also inform that the filter cartridges are pretty clogged. I have 4 - PA100N cartridges. I have pavers around my pool. I recently power washed the pavers and brushed new paver locker in between them. Very fine sand with cement in it which actually hardens like cement after spritzing with water. For the first week or so after doing this A LOT of this sand gets in the pool which gets sucked up and pretty much ruins my filters. Could there not be enough pressure causing the heater to not run? Although water is coming out of the returns, it seems at maybe half the pressure. I also replaced the pressure switch in the heater so that is new too. I definitely hear the gas valve opening and closing and it does in fact ignite during all three attempts however, it won't stay lit. Any ideas?
Attachments
If that heater has a separate flame sensor (some models rectify the flame sense thru the igniter) it will lok like a piece of steel wire sticking into the pilot flame (if equipped) or in the burner flame. It needs to be fully engulfed with the flame to work. It also needs to be clean. Use steel wool to clean it, they do corrode somewhat. They work by completing the low voltage circuit to ground using the flame.
danpik said:
Yes, it is separate. exactly as you described and its brand new. It is located about 2-3" above the 3rd burner. What do think about taking it out, holding a torch to it while the burners are igniting? I'm assuming if the heater shuts off again then I can rule out the flame sensor not working....yes? Good idea? Bad idea?
A flame sensor can but connected to a volt meter and see if it is open, or broken. Check and see if you can get an Ohms reading.
petes914 said:
Probably wont work. The control board puts a small voltage signal out thru the sensor and uses the flame as a ground path. If it does not detect a current flow, IE, no flame, then it will not allow the gas valve to stay open. If you use a diffent flame source, the ground path will not establish. Be sure that all wires from the board to the flame sensor have good connections. Also make sure that the heater ground is intact. As far as replacing these, I have been in the home heating business working part time for a buddy when he needs help for over 30 years. In all that time I have only ever had to replace 2, maybe 3 flame sensors. Usually because of cracked ceramic insulators. Other than that a good cleaning with steel wool will get them going again. Heck, I even used a dollar bill once in a pinch to clean one.
Best thing to do is make sure the sensor is in the flame real good. If the burner in that area is not burning correctly due to rust then it may not be seeing the flame too well.
As far as testing the sensor, use an OHM meter as was suggested. Touch one probe to the sensor end and the other to the wire where it connects on the board. The reading should be the same as if you touched the two meter probes together.
petes914 said:
Good thing they're inexpensive.
Check continuity on the ground wire. If the flame sensor is in a good flame and the ground wire is in good condition and properly grounded, jump out the pressure switch and see if it helps any. It may sound crazy, but I've seen "rapidly firing" pressure switches that allow the circuit to close until rectification, which then sends the AGS code rather than low pressure. This wouldn't be caused by a bad pressure switch, but likely a minor suction leak or back-pressure issue at the return outlet. Still, the issue is much more likely a problem in proving flame.
How do I jump out the Pressure switch? if I remember correctly, there are two spade terminals on the pressure switch, one NC and the other O. Also, is the screw holding in the flame sensor the ground for it? I didn't make any effort to wire wheel any corrosion when I installed the new flame sensor.
Pull both wires and insert a jumper wire to connect them together. May or may not work as some boards now have logic to ensure you can't do this.petes914 said:
No, that is why the ceramic insulator is there. The current flow (electricity) comes from the board, up the wire to the probe and grounds thru the flame to the burners.petes914 said:
I plagerized this from another site to hopefully help you understand how this works.
The method used to prove flame in most gas-fired products produced in the last seven or eight years is often misunderstood. This method is usually known as “flame rectification.”
Many servicers believe the flame sensor takes an active role in proving flame, and because of this, believe the sensors sometimes fail. Let’s look at what happens.
In order to verify flame, the ignition control must establish current flow using the flame as a conductor.
The mechanics of flame sensing
When everything is working right, the moment flame touches the sensor, the module establishes and monitors this current flow.
The voltage at the sensor is ac (alternating current), but because of the great difference in mass between the flame sensor and the furnace chassis, this voltage is “rectified” from ac to dc (direct current), usually less than 10 microamps.
As long as this current flow exists, the ignition control will power the gas valve.
The flame sensor is not sensing anything. The flame sensor’s only “claim to fame” is that it is resistant to the effects of being immersed in flame.
A flame sensor can become coated with a silica-type material. (Silica is a component of glass and glass is a great insulator.) When this happens, all that is required is a cleaning of the sensor with a light abrasive.
That’s the mechanical side. Now let’s look at what can go wrong electrically.
Electrical snafus
We know that 115 vac has one hot leg and one neutral. The black (or common) leg has the potential to ground. The neutral does not.
Apply this to what we just learned about flame sensing and think about what will happen if a furnace is installed with the neutral and common reversed.
The module must establish current flow through the flame to ground, right? So if the black and white are switched in the junction box or the receptacle, there is no flame sense because there is no voltage potential.
Everything else in the unit works fine, but a few seconds after the burners light . . . the module closes the gas valve because the power for the flame-proving circuit is not there.
What if the common and neutral are connected properly, but the flame still drops out for “no reason?”
Check the ground to the unit. Here’s how:
You have already measured between common (black) and ground and read 120 vac. Now measure between neutral (white) and ground to be sure you have no voltage (0.0 vac).
Remember, your flame-sense current is very small, usually less than 10 microamps dc. Think about what would happen to the flame-sense current if there were another voltage potential at the furnace chassis because of a poor ground.
The ignition control needs a clean, properly polarized voltage source to do its job.