Ultra 155 E02 Low Spark

ktm250rider · April 30

I have a Weil Mclain Ultra 155 series 1 which keeps throwing an E02 code. I went through and did a boiler maintenance, cleaned the heat exchanger, cleaned the combustion chamber, replaced the igniter. Unit worked great for a couple days but the error came back. Noticed that the spark seemed "low". Meaning you could barely hear it. Checked the Ignition cable and it was on the low side at 955 Ohms. Replaced that but still no change. The spark seems very week. Any ideas where to go next.

GGross · April 30

does it work sometimes?

if it does I would look at a few things. first the easiest, check static and dynamic gas pressures are in range for your fuel type when the unit is off, and at high fire.

next I would check to make sure your flue pipe doesn't have a belly forming, holding back condensate and creating a restriction in the flue (check both vent pipes for any blockage)

clean the condensate trap

955 is within tolerance according to the WM manual so that cable was never an issue.

what were your steps for " a boiler maintenance, cleaned the heat exchanger, cleaned the combustion chamber" to me these three things are all the same task, just stated 3 different ways. can you elaborate what you did? and do you have photos of the finished cleaning on the fire side of the heat exchanger? did you get anything like coffee grounds to flush out of the drain?

any other odd things with the unit? harmonic sounds from the flue pipes? weird noises etc

ktm250rider · May 1

i followed the manual for boiler maintenance using the flat bar cleaning between the heat exchanger, vacuumed out all the debris, checked the condensate trap, replaced igniter and seals and cleaned the combustion chamber. dont believe i missed anything.

yeah i didnt think it was the cable but since the unit is 17 years old and it was on the low side of the tolerance i was hoping that would be it.

The only odd noise is the lack of noise from the igniter. it used to snap or crackle during ignition. Now its almost silent like there is no spark.

I did check the low voltage terminal 9 to ground and it was only 2.2v during ignition. checked ground to X1-6 which was good. Unfortunately, this path leads me to a new control module.

HVACNUT · May 1

Series 1 Ultra? Original block?

Get your analyzer out, bump start it, and tune it.

Natural or LP? Do you know the pressure drop across the gas valve during TFI?

109A_5 · May 2

There may be multiple issues. Low flame signal and the weak spark. Although I believe flame signal is only valid when there is a flame present " only 2.2v during ignition "

pedmec · May 3

you skip a very important step in your maintenance procedure and that is blowing out the mesh burner. the mess will get plugged during operation and needs to be blown out with compressed air at at least 90 PSI. The mess will look fine until you start blowing it out and then you start seeing all the debris come flying out. you can also wash with simple green but i like to use air so i don't have to wait to dry. Did you even do a visual inspection of the burner to see if the mesh was sagging?

what series weil-mclain do you have?

ktm250rider · May 4

I have a series 1 Ultra 155. I thought the service manual said to NOT blow out the burner. I vacuumed it out with a shop vac and bristle brush.

Remove three M4 hex head screws (7mm box end
wrench) and burner clips securing burner to cover
plate. Remove cover plate.
Use a vacuum cleaner to remove any accumulation
on the heating surfaces. Do not use any solvent.

Had service tech come out. He verified that the incoming gas pressure was incorrect.

PeteA · May 5

so @ktm250rider the gas pressure being incorrect was the cause of the weak spark? Or was that one of the things that you've also checked and fixed but still have a weak spark?

109A_5 · May 5

pedmec · May 5

So what kind of gas pressure did you have? there is a an operating range to work with when it comes to incoming pressure. If you have the correct incoming then the more important number is how much of a difference in pressure between your static and dynamic pressures. Where do you stand now??

ktm250rider · May 7

we had to call in a tech for the gas measurements. Unfortunately, i was at work. Talked to him on phone he mentioned static reading was 11 and dropped to 10 during ignition (i forget the units).

HVACNUT · May 7

https://forum.heatinghelp.com/discussion/comment/1896004#Comment_1896004

If measured in inches water column, that's good for LP gas. Surely the tech did a combustion test.

Is it the original block? Have checked the condition of the block by the drain?

109A_5 · May 7

https://forum.heatinghelp.com/discussion/comment/1896004#Comment_1896004

pedmec · May 7

Did he get it running? Did he have a vacuum downstream of the gas valve? what are we doing here?

Ultra 155 E02 Low Spark

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