Steam Boiler Temperature Drop

January 12th, 2021, 11:49 pm

Why does our Steam Boiler temperature drop by more than 10˚F on the PID display while steaming - even before there's a call to refill the boiler?

I understand the rapid drop in pressure but why in temperature?

#2: Post by **Jeff** » January 12th, 2021, 11:56 pm

When in equilibrium, the steam temperature and pressure are interrelated. "Saturated steam table" is a good search term.

One example is https://www.engineersedge.com/thermodyn ... metric.htm

Is this in line with what you're seeing?

0.9 bar ~ 246°F
1.0 bar ~ 249°F
1.1 bar ~ 252°F
1.2 bar ~ 254°F
1.3 bar ~ 257°F

January 13th, 2021, 12:05 am

Thanks very much Jeff, that makes perfect sense. I'll check the PID display & Steam Boiler Pressure Gauge next time. It lines up with what I remember.

#4: Post by **godlyone** » January 13th, 2021, 10:14 am

Ideal gas law... PV=nRT

#5: Post by **EddyQ** » January 14th, 2021, 8:19 pm

On my KvdW, the PID probe is in vapor above the liquid in the boiler. The reason they measure temperature there is due to a more rapid drop in temperature (as described above). The fast drop due to steaming quickly turns on the heat which has some lag. The end result is apparently more stable boiler temperature.