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Hoping someone could help me. The steam boiler pressure seems to to build up so high that it creates a pop of steam. Here is what I have done to try to resolve the problem.

1. Clean fill probe with vinegar
2. Clean vacuum breaker with vinegar
3. Clean temp probe with vinegar
4. Clean pressure relief valve with vinegar
5. Confirmed the water only fills slightly above the fill probe's length

Here are some insights
1. When the boiler starts from cold, there is some light splatter off the vacuum breaker. Very small amounts. This is surprising giving that there is at least 2 inches worth of breathing room between the water and top of the boiler.
2. Vacuum breaker closes itself when temperature reaches around 200 degrees
3. My steam boiler is set to 252 degrees. The steam seems to pop at 249 degrees. If I lower the temperature to 245, it seems to stabilize, however, still have constant steam hissing noise.

https://www.youtube.com/watch?v=U6EmtnT9JVM

Thanks for your time!

I see from the video that your steam pressure is about 2.1 bar. It should be running about 1.2-1.3 bar so I am not surprised that the pressure release valve is kicking in(if that's what it is.)

I assume the steam is coming from the pressure relief valve though I can't tell from the video. If so and if you still get leakage when the temp is set to produce no more than 1.3 bar, then you should replace it.

Hey Chas.. thanks for the response. Do you mean to replace the temp sensor? I have one on the way along with a pressure regulator.

The steam pop is from the relief valve.



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I also lowered the boiler temp down to 240. It stabilizes with slight hissing, then after 10 minutes, pressure builds back up above 2. Does that indicate a failed temp sensor?

I've had this issue when a tiny bit of debris was caught under fill solenoid seat. This causes a constant leakage into boiler on my plumbed in dream.

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I've also had this issue and have replaced the fill solenoid :) My current issue is not leaking of the boiler but over pressure. Not sure if its a temperature issue or how does the pressure normal exit/maintain?

Control of the temperature controls the pressure. So if your temp transmitter is drifting low, it will cause the boiler to overheat and cause the pressure to go high. Your indicated temperature it will appear normal since it is being read by the bad temp sensor. These machines have a history of temp sensor failures ( usually in brew boiler but occasionally in steam boiler). Just be aware that it's not so easy to change out the steam boiler sensor. Very crowded on top of that boiler.

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