Master Temp 400 Won't Ignite

superray

Bronze Supporter
Jun 24, 2012
51
NASA/ TX
I was hoping to see if someone had any other suggestions before I throw in the towel and call someone. I am having trouble with my Pentair Master Temp 400 and I can't seem to resolve the issue.
The unit seems to go through its safety checks and tries to start, I can hear the gas valve open and smell gas but no ignition occurs. The unit tries a couple more times, then lockout.

Replaced:
  • Control Board (current rev R14)
  • ICM (Fenwal model 35-662944-013) (new)
  • Keypad (went with iFJF when I replaced the control board, the Pentair keypad has a red window and this one was clear for the LCD versus LED display)
  • Igniter (Etna model 777-7-0054) (old igniter did bad at all, and I don;t recall the resistance, but was replaced with a new one anyway)
When the board calls for heat, I see 247 VAC to the igniter from the ICM (pins S1/120 and S2) (20201220_123825.jpg), but then it drops within a very short period of time.

Video 1
Orange Meter is the ICM voltage output to the igniter leads (S1 and S2)
Yellow Fluke meter the FC pins output in Volts from the ICM: 20201220_123233.mp4

Video 2
Orange Meter is the ICM voltage output to the igniter leads (S1 and S2)
Yellow Fluke is the PIN pins in uA : 20201220_123546.mp4

Video 3
Phone camera in stack to observe there is no water in the flame pot or leaking coils (look's bone dry to me) : 20201220_123546.mp4

I also added, using automotive jumper cables, an extra ground to the grounding point from one of the blower bolts to test in the flame current was an issue: 20201220_123546.mp4
based on the Fenwal document (https://kidde-fenwal.com/Media/Technical Articles/Fenwal_Controls-TA-Improve_Grounding_Gas_Ignition_Controls-F-35-1002.pdf) noted in the troubleshooting guide.

History
There are no diagnostic LED's illuminate of the board, except for the Service Heater when it's is done trying to cycle and the ignition control lockup (3 flashed on the ICM).
This unit is about 10 years old and was functional without issues. When I was away on business for a few months I has someone staying at the house, when a storm blew through they noted that the blower would make a ticking noise and the blower would not start. In an attempt to fix it, they replaced the blower from a spare parts unit that I had bough awhile back (for the panel covers) and sitting in my garage. The blower is currently functioning and sucking air very strong so I don't believe there was any issue with that (seemed pretty straight forward to replace) so I don't thing that is the issue. I don't note any rodent chewed wires and I checked all the connection to the sensors. The HLS was replaced awhile back.

Is there anything that I am overlooking are obvious to others with experience with this heater? Should the voltage at the iginter drop like that so quickly and not re-power when it tries for it's second and third attempts before going into lockout? I have tried a couple ICM and they all do the same thing it seems like (these were bought used in working condition) so I bought one Brand New to ensure that I wasn't swapping a bum part for a bum part.

Really would like to use the hot tub this season and I don't know what else is causing the unit to not fire. Any help would be appreciated.
 
Last edited:

superray

Bronze Supporter
Jun 24, 2012
51
NASA/ TX

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,338
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
You sure you have gas and proper gas pressure?
 

superray

Bronze Supporter
Jun 24, 2012
51
NASA/ TX
You sure you have gas and proper gas pressure?
Unfortunately no, as I have no way to test that myself, I can smell gas when it initally opens the valve but nothing has changed with respect to gas line, regulators or anything like that I am aware of.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,338
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
When was the last time the heater worked?

We have seen water in the gas line, corroded pipe, or collapsed pipe as reasons gas flow was not to spec.
 

superray

Bronze Supporter
Jun 24, 2012
51
NASA/ TX
About a year ago was the last time it was used. It doesn't get used for most of the year as it's in Southern Texas. I'll have to call someone to eliminate that as a potential issue as see where we are at. Thx
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
22,338
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Gas heaters should be run every few weeks for 15 minutes or so. Letting them sit idle for long periods of time leads to corrosion and various problems.
 
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