Mastertemp 400 no ignition, low voltage to igniter

[greghodg]

My ~2016 MasterTemp 400 suddenly stopped igniting. Normal no ignition, I smell gas, hear click, etc. No puff of heat, no sound of ignition.

It wasn't getting hot anywhere around the igniter, as measured with an infrared thermometer, so I assumed it was the igniter and ordered a new one without checking. The existing one looked and measured fine when I pulled it out but I replaced it anyway.

When that didn't make a difference, I measured the voltage going to the igniter. After connecting a multimeter, upon reapplying power, there was an idle ~16VAC on the igniter leads. When it kicked on, I only measure ~76VAC to the igniter.
The troubleshooting guide suggested replacing the ignition control module, so I got a new Fenwal and replaced that, which has also made no difference, still only getting 76V to the igniter leads.

I don't see any evidence of damage or wear to the wiring inside the heater. Any ideas before I give up and call Pentair?

240V supply.


Thanks
G

 

[ajw22]

Welcome to TFP.

Have you confirmed you have 240V at the heater..

Do you have the RED plug in for 240V?

Check that the igniter resistance is 50 ohms.

What is your input voltage at L1 and L2 on the Fenwal ignition control?

@swamprat69 may have ideas.

 

[JamesW]

https://www.pooltek.com/wp-content/uploads/2017/02/Heater-PentairMastertemp.pdf

 

[swamprat69]

Took a look at the installation/users guide, this is the one that I got https://www.pentair.com/content/dam...p/manual/Manual-MasterTemp-472592-English.pdf What fault/errror code are you seeing when the heater does not fire? From what I can see the heater does not use a separate flame senser, but senses the flame through the ignitor itself (to ground). This setup was commonly used in early systems that used a hot surface ignitor (HSI) and a separate flame sensor was added as a modification to increase reliability later in many systems. It is imperative in these sysems that the grounding surface be clean bare metal with no dirt/corrosion as the flame is sensed through the ignitor/flame/ground. If you are not igniting at all and the ignitor is working correctly ( ignitor should draw ~ 3.5-5.0 amps when powered ), then I would look to ignitor positioning, or a problem with gas pressure (incorrect) /air pressure (air orifice inlet blockages/combustion air motor not up to correct speed or something else that would effect flame pattern). It is difficult to tell from the parts blowups and without having a heater to examine the exact positioning of the parts in order to determine where to look for the cause of the problem.

 

[greghodg]

Hi! Thanks for the replies. Ill cut to the chase.

> Check that the igniter resistance is 50 ohms.

Measured 68.5 ohms on the one i removed.
Checked the new one I just put in, shows 0 ohms... Pulled it out, the entire center section is missing :smh:
I was super careful putting the new one in, I have no idea how the center part broke off. Looking through the igniter hole with a flashlight I can see the little center bit laying inside.

So I put the old one back in, and fired it back up and it lit up fine, with the original igniter.

I'll test replacing the Fenwal with the original one as well to see if that was actually a problem but right now we're just stoked to get some heat in the spa.

Thanks again for the help!

G