Jandy JXI400N - Trouble Air

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PoolGate

PoolGate

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TFP Guide
Jun 7, 2017
9,462
Damascus, MD
Pool Size
29000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Jandy Aquapure 1400
My Jandy JXI 400N will not fire. Watching it when it tries after 5 seconds the fenwall goes to a single flash of the red led which is listed as the air pressure check.

Is it likely that this is the air pressure sensor or some sort of fan? I can hear the fan running when I call for heat. I am unsure what is supposed to come on and don't want to buy something that I don't need.

Can I jump/bypass this switch momentarily just to see if it fires so I know for sure it is this part?
 
When you call for heat the first thing that turns on is the air blower.

The air pressure sensor then senses that the blower is operating and gives the FENWAL the ok to start the gas ignition sequence.

You can not jumper the air flow switch as the board checks that the switch is open before it starts up the blower. If you jumper the switch the board will error out.

Use a multimeter to check the operation of the air sensor switch. Disconnect the wires to the switch and connect your multimeter probe to the switch contacts. You should see the contacts close when the air blower runs.
 
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I just checked the pressure switch off the heater using an ohm meter and applying air pressure to the port. You can hear an audible click and the meter changes from OL to 0000 so I think the switch is working. I will test it while trying the ignition sequence and see if something else is going on.
 
I also realized my blower connection to the heat exchanger is leaking. This makes sense because I always find water around the base of the heater I always assumed it was condensation. I don't think this is related to the pressure issue. I pushed on it and the bubbles stopped so I think just tightening these bolts will fix this.

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Heater Issue Jandy JXI400N

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I suspect your heat exchanger is leaking.

There should be no water at the blower connection. The heat exchanger is a sealed loop with water flowing through it from the header. No water should be getting out of the heat exchanger anywhere inside the heater or burner can.

Heater_Jandy_JXI_cutaway.png
 
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Poolbreh said:
I would check for 24 vac across the ps and ground on fenwal. It will tell you if the switch and wiring is closed or open. Black and yellow is from thermostat.
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So between the terminal marked "PS" and the terminal marked "GND", right? One of the yellow striped wires from the "W" terminal also goes to the pressure switch. Should it be 24 volts when the heater is trying to fire? Or all the time?

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ajw22 said:
I suspect your heat exchanger is leaking.

There should be no water at the blower connection. The heat exchanger is a sealed loop with water flowing through it from the header. No water should be getting out of the heat exchanger anywhere inside the heater or burner can.

Heater_Jandy_JXI_cutaway.png
Click to expand...

This has been leaking for a long time. I just checked the 4 bolts though all were loose. I tightened them all and no more leak. :)
 
The afs checks the differential of airflow if the combustion chamber is full of water it would disrupt it. It might explain the hsi you’ve been going through. You would get 24 vac almost immediately before any prepurge. If the exchanger is leaking the heater is toast 😔
 
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Poolbreh said:
The afs checks the differential of airflow if the combustion chamber is full of water it would disrupt it. It might explain the hls you’ve been going through. You would get 24 vac almost immediately before any prepurge. If the exchanger is leaking the heater is toast 😔
Click to expand...

It wasn't leaking except out of the connection point gasket (see video). I assume water is supposed to be in that area (underneath the gasket). Water was leaking out of the gasket connection and just draining onto the ground below the heater. The heater has been leaking for at least 2 years as I have been noticing water under the heater. It has never affected operations before. I could take off the blower part (those 4 bolts I tightened) and look I suppose but not sure what I am looking for.
 
Ah - DOH! Ok I think I understand what you guys are saying. That connection point is an air/fuel connection, not water. So it should never leak water. I will take the blower motor off. If I see water under it, then the heater is toast? Or the exchanger can be replaced?
 
The exchanger can be replaced if you are willing. Your hsi will most likely need replacing as well. You shouldn’t have any water in the combustion chamber. It also explains some of the connectors seem to have a little rust.
 
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I just removed the ignitor and the combustion chamber is 100% full of water. Strange thing though it did not pour out and the pool was running. I even bumped the speed to 3450. I would think if the heat exchanger is leaking, it would leak all the time and be running out of the open chamber. I wonder if there is any other way water can get in there?

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The only other way water can get in is through the exhaust vent.

Maybe if the bottom is clogged and the rain fills the vent and the rain water goes into the exhaust vent.

In this picture from last year, the heater has a lot of water around the base.

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JamesW said:
The only other way water can get in is through the exhaust vent.

Maybe if the bottom is clogged and the rain fills the vent and the rain water goes into the exhaust vent.

In this picture from last year, the heater has a lot of water around the base.

View attachment 423153
Click to expand...

Yep that is last year. Last couple years it has had water at the base. I just assumed it was condensation. It might be a slow heat exchanger leak and running the heater boils away the water. I don't think it is getting in through the exhaust. It is under the deck so mostly protected from rain anyway and I checked that exhaust vent it has drains and they are clear since it is just holes in the sheet metal. I am going to rip into it and see if it is the exchanger. I'll need to run a bypass I think since I don't want to manually chlorinate. I guess I can check the water in the combustion chamber for CYA (or even chlorine). 😂🤣😉
 
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