[nvshooter2276]

I had 3.5 gallons of water at 71 degrees. It took my gas stove 77 minutes to reach the 204 degrees at which tap water boils at my 4150' ASL. Is that period of time "good" for such a pursuit? I use an aluminum heat-spreader that's the same diameter as is my kettle; good for lessening a really hot spot in the center of the kettle that might lead to scorched wort.

[Megary]

Without knowing the BTU’s of your gas burner, it’s hard to say. Seems a little slow, but not unreasonable for a kitchen stove.

I heat approximately 5 gallons of water on my stove.

Takes me about 40 minutes to heat my 55F well-water to a mash temp of 152.
Another 25 minutes to get from mash temp to boil (212).

[Drewch]

That seems slow, to me, for 3½ gallons.

[nvshooter2276]

Without knowing the BTUs of your gas burner, it’s hard to say. . .

I've read that the burners on gas stoves for home kitchens put out about 7,000 BTU. Just looked it up and 7,000 BTU is correct. If your stove has a big burner in the middle, that one could go as high as 12,000. You put your big pasta pot on that one. Or your eight-gallon kettle...

[Richard]

That is about twice as long as it should take if all of the 7000 BTU went into the water.

[Bob357]

If you're going straight to a boil, I assume you're doing extract brewing. If that's the case, you can save time and gas by not using the heat diffuser until you cut the heat to add your extract. 

[neuse]

It takes me about 20 minutes to heat 2.5 gallons of roughly 70 degree water to boiling (212). 77 minutes seems really slow for your 3.5 gallons. Bob357 might have hit on the answer.

[Richard]

If you are just heating water you can also use multiple pots on multiple burners, heat some water in a microwave or coffee kettle, etc.

[nvshooter2276]

If you're going straight to a boil, I assume you're doing extract brewing...

Yes; I'm an extract-only brewer. I work too much to have the time to do the all-grain stuff. I will do a second test without the flame-tamer. The original water is still in my kettle. Because it's been boiled once, will the time-to-boil for the second test be less than for the first? I'm thinking Yes, because any gaseous impurities have been boiled out. All the chlorine my town uses in the city water has also been boiled out.

Should I start with unboiled water from the tap, so as to replicate the first test-- which was also unboiled water? The water I will use when I actually get to make some beer will be from a PU̅R® on-faucet charcoal filter. It's dam-ned good for removing the chlorine smell in our "liquid gravel" city water. The filtered water tastes good, too.

It's over a hundred degrees outside, right now. I have to go do a little shopping. Not looking forward to going out there and melting like a cheese sandwich left on the dash of an automobile, but the stuff I want to buy won't drive itself to me. To quote Dan Rather, "Courage..."