How hot is a gas burner supposed to be?

Question

My new range has a 17000 BTU burner (natural gas). It my first gas range. I have the feeling it is not that hot.

• I can barely keep pasta water boiling (8 cups of water) with the broiler on high. I expected I'd have to lower the heat in order to avoir overspils.

• I was not able to burn hamburgers in a cast iron pan. Not that I wanted to burn them, but I again I expected I'd have to lower the heat. I kept it on high for several minutes without any serious damage to the meat.

Q1: How can I test if the burners are as hot as what they should be?

Q2: Can something be wrong with the connection?

Maybe my expections are too high after everone told me how amazingly hot and fast gas ranges are. The flames are blue so that seems to be ok.

Answer 1

BTU means British Thermal Unit. So:

lbs of water x temperature rise = BTUs required for one hour (British units)

(1 lb of water x 1 degree Fahrenheit) = 1 BTU for reaching temp in 1 hour (approx)

Let's do a simple calc:

1) Suppose a 30% efficiency (you are heating air and pot too)
2) Four lbs water
3) 70 F as water initial temperature (212-70 = 142 to boil)

So:

(4 lb water x 142 F) * 3.,33 (eff) = 1900 BTUs for reaching boil in one hour

17000/1900 = 9 (your burner output / required output to boil in 1 hour)

60 mins / 9 = 7 mins

So you could expect bringing to boil your 4 lbs of water in 7 mins in a 17.000 BTU burner starting from 70 F . Normal pressure and altitude, of course.

Here is a video of a 17.500 BTU burner working to compare with yours.

Keep in mind that many approximations were done in this calc. No evaporation, medium to heavy pot, etc.

Answer 2

Something is very wrong there; you need to get this serviced right away. 17,000 BTU should be enough to keep a full rolling boil going on a pot much larger than 8 cups, or sear the daylights out of your burger. I'd go so far as to say I wouldn't use it until a service tech has looked at it.

Answer 3

The relevant calculation here is equilibrium: once the water's all at 100C, how much can you boil per second? belisarius' answer, estimating time to reach boil, is good too, but there are more variables involved, and it's that rolling boil you're trying to watch anyway.

All you need to know here is the latent heat of vaporization for water. Assuming 100% efficiency:

17000 BTU/hour / (970 BTU/pound) = 0.0022 kg/s = 2.2 gram/s

Scale that down by the fraction of the heat that goes into the pot instead of the air (probably 30-50%? this includes heat loss out the sides of the pot); you should probably be expecting more like 1 gram/s. That's a pretty good amount of water to vaporize per second! Remember that while that's only 1 mL of water, steam is a lot less dense. A gram of saturated steam is 1.7 L at 1atm, 100C. Yikes!

Upshot: yeah, you should have a lot of boiling going on there.