# Pulsating noise in SuperHot Saturn boiler when firing



## Koolkat (Jun 30, 2013)

I was at a no-heat call at a small apartment building (18 suites, 3 storeys). I had gotten the call from a tenant on the second floor, who told me his apartment was cold. When I came into the building, I noticed the corridor was cold and so was the radiator there, so I suspected the boiler. This was before I even went up to the complainant's suite. On entering the mechanical room, I found that the pilot was off in the boiler, so I cleaned the pilot, replaced a burned-out thermocouple, reinstalled the pilot, and lit it. I started the boiler. It fired up fine, and started heating up. The pump was running, and the feed and relief valves seemed all right. I started to notice this thumping or pulsating sound. It wasn't really loud, but the expansion tank was shaking in rhythm with the sound, and the 0-30 psi pressure gauge on the feed water line was jumping up and down from around 21 to the max. This happened only when the boiler was firing, and stopped when it shut down. The boiler heated to around 210F, but the double gauge on the boiler said 210 on top, and 10 psig on the bottom. Aside from this noise and pulsing, heating performance is normal. Any ideas?


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## PlungerJockey (Feb 19, 2010)

My first guess would be the expansion tank is bad.

The water is expanding as the boiler fires.


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## wyrickmech (Mar 16, 2013)

Koolkat said:


> I was at a no-heat call at a small apartment building (18 suites, 3 storeys). I had gotten the call from a tenant on the second floor, who told me his apartment was cold. When I came into the building, I noticed the corridor was cold and so was the radiator there, so I suspected the boiler. This was before I even went up to the complainant's suite. On entering the mechanical room, I found that the pilot was off in the boiler, so I cleaned the pilot, replaced a burned-out thermocouple, reinstalled the pilot, and lit it. I started the boiler. It fired up fine, and started heating up. The pump was running, and the feed and relief valves seemed all right. I started to notice this thumping or pulsating sound. It wasn't really loud, but the expansion tank was shaking in rhythm with the sound, and the 0-30 psi pressure gauge on the feed water line was jumping up and down from around 21 to the max. This happened only when the boiler was firing, and stopped when it shut down. The boiler heated to around 210F, but the double gauge on the boiler said 210 on top, and 10 psig on the bottom. Aside from this noise and pulsing, heating performance is normal. Any ideas?


sounds like a no flow condition check to see if the valves are all open and you have flow the noise is possibly water boiling in the heat exchanger this would make spikes in pressure noise and high heat.


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## ASUPERTECH (Jun 22, 2008)

Sounds like $ sooner than later. That's the sound of you heating up sludge...


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