Pentair Mastertemp Ignition Lockout

ToddMan

Member
Sep 17, 2019
6
Chicago
Hi, my heater is firing up, heats for 5 seconds and after several tries it stops and get the 3 blinks indicating “Ignition Lockout” I just replaced the thermal Regulator, Main Control Board, the ignitor, stack flue sensor and manifold bypass...was getting ready to replace ignition module but I got it to work and heat the pool a few days ago...now it’s doing the same thing; I called my pool tech and he is also stumped as what it is that’s causing it not to stay lit.
Pentair customer service thought it might 1 of these 3 things:
Ignition Control Module?
High Limit Switch?
Automatic Gas Shut Off Switch?
Anyone have a similar issue or same that could help point me in the right direction? Frustrated in Libertyville IL
Thanks Todd
 

JamesW

TFP Expert
Mar 2, 2011
16,540
The Fenwal should have two test points for flame current fc+ and fc-.

Check the flame current using a multimeter that can measure microamps.

Flame Current Measurement

Flame current is the current that passes through the flame from sensor to ground.

To measure flame current, connect a True RMS or analog DC micro-ammeter to the FC+ and FC- terminals.

Readings should be 1.0 µA DC or higher.

If the meter reads negative or below "0" on scale, meter leads are reversed.

Reconnect leads with proper polarity.

Alternately, a Digital Voltmeter may be used to measure DC voltage between FC+ and FC- terminals. Each micro-amp of flame current produces 1.0 VDC. For example, 2.6 VDC equates to 2.6 µA.

A good burner ground that matches the control ground is critical for reliable flame sensing.
 
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JamesW

TFP Expert
Mar 2, 2011
16,540
The Fenwal has flame current test points, which are pointed out in the manual.

Once the unit fires, you should get a good flame current.

If the flame current is good, the Fenwal ignition control is probably bad.

If the flame current is weak, it could be a weak flame or maybe a grounding issue.
 
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ToddMan

Member
Sep 17, 2019
6
Chicago
I really appreciate the replies. Thank You
I replaced the ignitor a few weeks ago so I will run the test on the module...I thought it might be bad so I was going to replace it but then the heater worked great... then
stopped...same code before as before I got it to stay lit, so I thought maybe it wasn’t the module because it began to work
 

JamesW

TFP Expert
Mar 2, 2011
16,540
How old is the unit?

Do you have a picture of the heater?

You might have a leak in the heat exchanger. Remove one of the bottom bolts from the manifold to see if water comes out.
 
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ToddMan

Member
Sep 17, 2019
6
Chicago
How old is the unit?

Do you have a picture of the heater?

You might have a leak in the heat exchanger. Remove one of the bottom bolts from the manifold to see if water comes out.
Hi, I replaced the manifold bypass and thermal regulator a few weeks ago and didn’t have any water coming out;
here is a picture of the model and serial number. Thank You, Todd
 

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JamesW

TFP Expert
Mar 2, 2011
16,540
If you removed the manifold and no water came out of the bolt holes, that's good.

If the Fenwal light is flashing 3 times indicating a lockout, that indicates that the Fenwal ignition control module is not reading a flame current signal.

Do you have a picture of the Fenwal?

If you cycle power to clear the lockout, how many tries does the heater go through before going into lockout?

Do you have a good "true rms" multimeter that you can to test the flame current?
 

ToddMan

Member
Sep 17, 2019
6
Chicago
If you removed the manifold and no water came out of the bolt holes, that's good.

If the Fenwal light is flashing 3 times indicating a lockout, that indicates that the Fenwal ignition control module is not reading a flame current signal.

Do you have a picture of the Fenwal?

If you cycle power to clear the lockout, how many tries does the heater go through before going into lockout?

Do you have a good "true rms" multimeter that you can to test the flame current?
I believe 3 times it will fire up for about 5 seconds and stop and try again.
I don’t have a “true rms’ multimeter unfortunately...is it possible for the heater to have worked after having the same problem if the Fenwal is bad?
(Had the same issue then it worked and now it doesn’t again) I was going to replace it but it started to work again
Here is a picture of the Fenwal:
 

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JamesW

TFP Expert
Mar 2, 2011
16,540
I would get a good multimeter and check the flame current.

The flame current needs a good ground path from the burner to the Fenwal.

If there's corrosion in the connection between the burner and chassis or Fenwal and the heater chassis, the flame current won't make the path from the Fenwal to the flame sensor, through the flame, to the burner and back to the Fenwal.
 

ToddMan

Member
Sep 17, 2019
6
Chicago
I would get a good multimeter and check the flame current.

The flame current needs a good ground path from the burner to the Fenwal.

If there's corrosion in the connection between the burner and chassis or Fenwal and the heater chassis, the flame current won't make the path from the Fenwal to the flame sensor, through the flame, to the burner and back to the Fenwal.
So before I got a chance to check, I thought I’d try to fire it up and like before it fired right up and stayed lit 🔥
Which is great but I don’t think I’ve solved the issue yet...thrilled it’s working but really want to know what’s causing the issue. It seems and might be coincidental, that when the air dries up (been having a lot of rain lately, yesterday and today it’s clear with little humidity) it will work.
Any thoughts? Would the ignition module work on and off? Might be right about corrosion for the ground...
 

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JamesW

TFP Expert
Mar 2, 2011
16,540
You definitely need to clean the ground connections.

A microcurrent has to travel from the Fenwal, though the flame sensor, through the flame, to the burner and then through the frame grounding back to the Fenwal.

You need to make sure that the Fenwal is securely grounded to the frame and that there is a good ground path between the Fenwal and the burner.

I would still recommend that you check the flame current to see what it is.

I suspect that it's probably borderline.

If you measure the current now, you can see if the flame current improves when you clean the grounding to verify that the grounding was the issue.