Boiler Carbon Monoxide Alarm!

We were jarred awake by our carbon monoxide alarms when the temperature was eighteen below zero. We immediately opened a living room and back hall door and let fresh air flow. We tried leaving the boiler on but when the alarm went off again I turned off the boiler completely. Of course our house is so warm the loss of the boiler was not too impactful. Even opening the doors did not reduce the inside temperature by much. That is the benefit of solar and lots of thermal mass. I learned another advantage to the combination water heater and boiler. The boiler on the Challenger can easily be set to be off while the water heater is still on. Later in the day I set it to domestic hot water only. The water heater did not leak carbon monoxide. I tested the boiler with a gas sensor that I have for the RV.

I inspected the boiler later in the day and realized the condensate drain was pretty dirty. The troubleshooting chart said to be sure the exhaust and the exhaust fans were working which seemed to be the case. The boiler fan is making a whining noise when the boiler temperature is very high. The modulating temperature setting will react to really cold weather by heating the water more. I changed the top water temperature to 170 degrees from the default 186. The default water heater temperature is 140 degrees but the pump stops running at 120 degrees plus we have a whole house temperature regulator.

When I removed the boiler cover which only requires removing two screws, I cleaned the inside of the boiler and blew on the fan motor, then disassembled the condensate pan and cleaned it thoroughly and reinstalled the pan. This is the process that I go through when starting the boiler each winter. But apparently the condensate had built up more char than previous years. I unplugged the fan motor and ensured that it was getting appropriate power too.

When I put it back together there was an E5 error message. The error chart says to check the condensate vent and gas valve. I had just cleaned the condensate drain and tested to be sure the drain pipe was clear. So that error confused me and I did a lot of online research regarding malfunctions and fixes. These were all copied from internet help sites.

Triangle Tube Challenger Troubleshooting

  • Blower replacement check power inputs 120v and 20-32 v Dc. Blue and red wires to check DC, Black and white for 120v. 
  • Check flue back pressure switch
  • The unit was failing because it wasn’t getting spark, (you should see spark thru the flame window or you can hear it clicking) It would spark properly when the boiler was cool, but after warm up it failed to provide spark and would display error # 4, let it cool off and it would spark as it should. This is why the boiler would seem to work well on low demand days in the beginning of the season, but would fail during high demand days. Changed the ignition transformer assembly #CCRKIT28 (which provides the spark) unit seems to be fine.
  • E-04 Failure to Ignite After Five Trials?

This will break down into three categories. 1) Is there fire occurring, but not proving? 2) Is the unit not producing fire at all? 3) Fire is established but after a short time (30 seconds)

  1.  If we are producing fire but not proving, this is a condition of lacking ground or a defective flame signal. The unit MUST have a dedicated power supply from the incoming distribution electrical panel, with a full sized uninterrupted ground. Be sure to remove the igniter and clean it. If more than 2 years old it would be prudent to replace it. Also check the condition of the orange ignition wire, make sure it has good connections on both the igniter and the ignition transformer. Insure that the wire is not touching any metal. The flame signal is determined by the ignition transformer. Since we cannot establish a flame, we cannot read the flame signal; therefore check the ignition transformer once again being sure of the condition of the connector on the wires.
  2. If we are not producing any flame, then we are missing one of the three ingredients needed for fire. Ignition, Fuel, and Oxygen. We will attach our manometer to the inlet port on the gas valve; we should have Approximately 6” of pressure for Nat. gas, Approximately 11” for L.P. We should be able to see the spark generated when the unit goes into ignition through the inspection mirror attached to the left side of the heat exchanger. It is normally very visible. Removing the exhaust pipe from the condensate pan to increase the airflow from the blower. If we ignite then, we are restricted either in the exhaust pipe, or in the heat exchanger. Examine the exhaust pipe and remove the plate from the aluminum block and examine the flue ways for cleanliness. During the testing with the exhaust pipe there should be a strong order of gas coming from the outlet, if not, with the unit re-assembled, place your manometer on the outlet port of the gas valve. During pre-purge there should be a ½ inch of negative pressure developed. When the ignition cycle begins, the negative pressure should disappear, if it does not it is a defective gas valve. 
  3. If the unit lights, proves but when the blower begins to slow, the burner goes out. There we have a combustion issue that will require the use of the combustion analyzer. Make sure that at a forced high fire, we have an O2 level of 4.3% and when forced to low fire does not change more than 0.2%.

  • Replace condensate drain assembly. Triangle Tube CCRKIT14 Condensate Drain Trap Assembly (85, 105, 125)

After all this research which took a couple of hours. I was prepared to open the boiler again and troubleshoot. However it was such a simple fix that I could have forgone the research. Much of it did not really apply to the problem the boiler was having. I also watched videos about replacing the fan in case the fan was not operating at full potential so I know what to look for if the fan breaks.

Removing the condensate pan and water filter requires loosening the vent pipe and turning the pan enough for it to get free from the bottom of the boiler casing. Although it is not shown here reassembly means locking the pan back into place and retightening the vent pipe retaining ring. When I opened the boiler case I immediately saw that I had neglected to retighten the ring. It was leaking and that was the error. While it was open I also noted that the fan was operating when the boiler was on.

Challenger Condensate Pan Assembly
Challenger Condensate Pan Assembly

As a side note the next night the Kidde Fire/Carbon Monoxide alarm woke us with a low battery alarm. We had sleeping guests so the alarm was very annoying and new batteries did not stop it. I ended up removing the whole alarm but reconnecting the red wire that links the alarms together. The next morning checking the glitch in the battery replacement I learned that the alarm has to be disconnected from power either by unplugging or shutting off the breaker, the alarm status removed by holding down the reset button and then the new batteries inserted and power restored. Nice to know if I remember it next time. I do replace the batteries about once a year and have seen battery replacement issues before but somehow the alarm sounding seemed to use up the batteries in that unit faster.

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