Pool heater check ignition fault

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evanwellens

evanwellens

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Jun 9, 2012
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Stony Point, NY
So I opened up our Jandy Legacy LRZ 399,000 to replace the insulation panels. While doing so I disconnected the unit to make examining the heat exchange easier. Once done trying to turn on the heat threw FAULT-CHECK IGN CONTROL. Now this happens now and then since I bought the unit. The company said it was my gas pressure. Well tonight the gas co measured 7 WC at the appliance. According to the spec 5.5 to 10 is the range. He mentioned it short cycled, which is what I've noticed in the past. It heat the element , maybe 5 10 seconds later you can hear the gas supply switch turn on . The sound of flames igniting occurs and instantly the gas supply switch turns off. While this happend once and a while in the past and would recover now it does not. The pump pressure is steady, the heater is installed in a well ventilated area... I'm at a loss. Any ideas , I'm running out of things to try and we close up soon, would be nice to have heat next summer.

Thx !!!
 
If the unit lights and then goers out and displays FAULT-CHECK IGN CONTROL, you probably have a bad flame sensor. You can try cleaning it with steel wool and see if that helps. If not, then you would bed to replace it.
 
You may want to check the burners as well while you are in the neighborhood. The flame sensor is mounted above one of the flame rails, somewhere in the middle of the tray. If the particular rail that is under the sensor is clogged/dirty and there is no gas traveling down the rail meaning that there would be no flame under the sensor to confirm flame.
 
I was thinking it was the sensor as well , but I found the following sequence in the technician workbook.. If the sensor wasn't rectified the valve should take 7 seconds to turn off no ? It's basically instant. Wondering if it's the ignition control or the Main board.

1. 120 VAC to Igniter - Igniter heats to 2600 °F. - 40 second heat-up.
2. 24 V is sent on the Brown wire to Gas Valve ... Gas Valve Opens.
3. AC Micro Amp signal sent to Flame Sensor
4. Burners ignite, AC Micro Amp signal is rectified to a DC Micro Amp signal.
5. DC Micro Amp signal returns to the Ignition Control on the Ground wire.
6. 5 seconds after Gas Valve gets power or when rectification is confirmed power to
Igniter goes off.
– If rectification is not confirmed power to gas valve shuts off after 7 seconds.
– 2 additional tries (3 total) then shut down/lock out.
– Turn heater off, then back to pool or spa to reset.
If the heater is not turned off it will automatically reset after one hour.
 
Thats a little quick. May want to revisit the gas pressure. I know that you aren't getting much time with the gas valve open but, you need to see how much the WC drops when the valve opens. You shouldn't get much more than 4 inches of drop between static, and open. EVEN IF the drop is still in the "workable range" printed on the service plate.
 
I had the gas co test.. they reported as at the appliance. Is the a reasonably priced device you might suggest to test the hookups on the gas valve?

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Let's say the gas is low.. what can be done? The utility says pressure is max allowed. Also why would this thing work for years..
 
There is an adjustment that can be made on the gas valve inside the heater. Over time a very few gas valves will start to go down hill and you might need to tweak but it's somewhat rare. I see them fail all together most of the time.

I don't see it mentioned here but is this natural or propane gas?
 

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evanwellens said:
I had the gas co test.. they reported as at the appliance. Is the a reasonably priced device you might suggest to test the hookups on the gas valve?

- - - Updated - - -

Let's say the gas is low.. what can be done? The utility says pressure is max allowed. Also why would this thing work for years..
Click to expand...

Not much can be done if your gas service/supply is low. A low water column could indicate too small gas line size, How long has this heater been in service before you made these repairs? If it had been previously operating normally, gas line size may not be the problem. I think you would also get a little more time before the heater would shut down from insufficient gas pressure, if it fired at all!

I know i said look at gas pressure before, but at this point, i'm thinking your heater is not reporting flame rectification, or an electronic ignition issue. (Its just) The quick shut down is the only thing that is not inline with a FR problem. You would normally get those 7 seconds from the time you hear the click of the gas valve opening to shutdown.

See, if the heater (fire or mechanical side) has a problem, the heaters control will give some time, those 7 sec, before it shuts down. the time is engineered into the system to give the heater (fire) a chance to settle down and fire properly in case there is some sort of temporary draft or wind issue. The more i think about this, the more i think it may be an electronic ignition CONTROL problem. The control part is failing. Problem is, you have two areas of control that can be causing this. There is the FENWAL. Basically a box of switches, that may not be holding the gas valve switch closed the entire time they are being told to. Or the main board that does the telling, may not be telling commands consistently (flaky commands).

Best recommendation: Find yourself a real sharp (meaning old) heater guy. You need a guy that would be willing to swap parts rather than force you to buy new ones regardless if it fixes the problem. Or you could just replace those two items your self with the thinking, well, i feel better knowing that all the electronics are now new, even then, there would be no guarantee that would be the fix...
 
Sorry it's been a while since I was working on this , winter brought other issues. I do see the heater fire up, stays lite for 1-2 seconds then the gas shuts off. Replaced the sensor yesterday , no luck. I'm thinking this heater is more trouble than it's worth. Local repair guys are 150$ / hr. That's going to add up quickly. Thanks for the reply !! Any suggestions on a replacement ? We definitely want something ~400KBTU. But hoping to get something that will last. This heater barely made 4 years, which seems quite poor. It's predecessor had 11 years on it.
 
Depending on who you hire and where you get the heater from, a new heater Could be anywhere from $2500.00 on up installed. You could get a lot of service calls for that amount. Refresh my memory, how old is this heater? Especially if it looks pretty good on the inside (not much or no rust) It may just be worth repairing.

edit: Boy, all i had to do is look at the last post, ok 3-4 years, How does the heater look physically?
 
It looks worn. The heat exchanger has a small leak. Animals destroyed the insulation, so I replaced it to find the supports we rusted badly. I didn't know much about pool heaters and trusted our pool people took care of it closing which I realize wasn't the case. New heater 1900 , I'd do the install. Otherwise I need to hire an electrian plumber and the pool co. To connect 3 wires 2 pvc fittings and arrach the existing gas line. A service guy is going to go through the tech manual, start replacing what I already have. @ least 3 visits , maybe 6 hours? 900$ + parts 1/2 the price of new. Now which model is the question...
 
You can go cupro nickel if you feel like spending the extra $$. However, if you don't maintain your water chemicals correctly, you will still ruin a cupro nickel heat exchanger. Just might take a little longer. I see it as unnecessary on a residential pool.
 
Note that a Cupro-Nickel exchanger is a bit less efficient than copper in terms of transferring heat to the water. You may or may not see a difference in the time it takes to heat up between the two.

Why did i bring it up then?

In buying the CP, you would be spending more for longer heat times. And like Paul said, you don't really need it.
 

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