It got a bit above 100 here yesterday, even though I'm up against the foot of the mountains living at 6000 feet, with 14,000 foot tall peaks less than five miles away to the West. But it was undoubtedly a few degrees warmer down 2000 feet lower in the valley below us just a couple of miles to the East. Not at all surprising for us here in the High Desert in July, less than 30 miles out of Death Valley!
Does your boilers produce steam faster than ours? I know water will boiler faster at 6000 feet in elevation, but at a lower temperature. Also you lose maybe 1-2 psi in vacuum than you have at sea level!
Well, it isn't quite as simple as all that. Yes, water, in an open container, boils at a lower temperature with altitude. In the old days, explorers like Fremont even used the temperature of boiling water to estimate their altitude for mapping purposes. However, in a closed container, like a boiler, altitude really doesn't enter into that side of the equation!
Altitude does enter into the equation on the other side however, in that at higher altitudes, you have fewer air molecules carrying the heat from the flame to the boiler shell or pot bottom. Furthermore, due to reduced oxygen availability, the flame does not burn as hot either.
As an aside, I worked for years at relatively extreme elevation of 12,500 ft above MSL (approx. 1/3 of the way up through the atmosphere) where cooking certain foods like rice, beans or pasta was basically impossible, due to the reduced temperature of the boiling water, thus a pressure cooker had to be used if you wanted any of those foods for dinner. Heck, even oatmeal was tough to cook to a soft mush like consistency and tended to be a bit "crisp", so breakfast could be impacted as well!