Does a net made of coiled up silver wires increase the efficiency of a gas range?

  1. There are rumors circulating recently on various forums on the internet that a net made of coiled up silver wires increases the efficiency of a gas range when placed on top of the gas burner while fuel is being burned. According to what manufacturers claim, this is done by using the reaction of the silver wire to the heat of the flames to ignite unburned fuel being exhausted from the gas burner. This supposedly reduces the unburned waste fuel from the gas range by 38%. Additionally, the manufacturers also claim in their advertisement threads that this net increases the concentration of the flame so that more heat is transferred to the cooking containers to maximize the utilization of the heat being generated by the combustion of the fuel. This device supposedly increases the percentage of heat transferred to the cooking containers from a conventional 57% to 68%. There are even videos of this device which show the flames becoming more concentrated as the device is placed on the gas range. The device costs only $2 per unit and is said to last for 1 year, but it supposedly saves $120 of fuel every year and this translates to a savings of $118 per year when the cost of purchasing the net is deducted. The question is, does this device really work or is this just a scam?
  2. jcsd
  3. Ordinary burner burns out virtually all gas, so if you reduce the margin (of, let's say 0.0001) by 38% it has no effect on total efficiency.

    On the other hand I may believe that such net changes the geometry of flame/hot air flow such, that the heat is more efficiently transferred to the pot.

    Current market price for raw silver is $40/ozt ($0.12/g). It means that if the net weights just 17g all its price comes from silver used for it.

    I remember such nets made of steel wires were commonly used when I was a child. 50 years ago coal gas was still in use rather than natural gas used nowadays. Coal gas burns much slower than natural gas, so the distance between the burner and the pot had to be bigger than in modern ovens - and such net helped to shape the flame flow.
    Last edited: Jul 31, 2011
  4. I am waiting for an answer from the staff here if this device is a scam or not. I hope they can provide me with assistance. It would be greatly appreciated. Thank you.
  5. russ_watters

    Staff: Mentor

    Hi - you got a great answer, so I'm guessing no one else felt the need to weigh-in.
  6. Well if the answer that the net helps to shape the flow of the flame for a coal gas fueled burner that requires a greater distance between the pot and the burner when cooking food, does this principle of needing to shape the flame flow also apply to modern gas stoves that use other types of fuels, most commonly, natural gas, propane, butane and LPG?
  7. It applies, but to much smaller extend than for coal gas.
    I believe LPG/butane ovens are pretty vulnerable to air-flow conditions too - that's why many butane burners, especially those designed to work in windy camping conditions are equipped with structures of wires helping to protect the flame from being blown out or deflected significantly.

    If you really want to check how big the influence of such net is: spend $2 (that is not that much...) and compare the times needed to bring a half gallon pot filled with cold water to boiling.
    Last edited: Aug 19, 2011
  8. russ_watters

    Staff: Mentor

    xts didn't say it worked, he only proposed a mechanism by which it might. I also might believe it could make a difference, but only a very, very small difference. You'd be better off just making sure the diameter of the burner isn't larger than the diameter of the pot!
  9. I believe the main purpose of those nets was to protect the burner from being blown off. Coal gas has very small flame speed, and the pressure of gas/air mixture in a burner was much smaller than in modern natural gas ovens, so they were much more vulnerable to blow. And, of course, those old times, there were no kitchen exhausts, so while cooking cabbage you had to open windows widely...
    Last edited: Aug 19, 2011
  10. So that means that if a gas stove using modern fuel is being used inside a kitchen which is an indoor environment, then the net which is used to protect the burner's flame form being blown off by wind is unnecessary.
  11. In addition to focusing/concentrating the gas flame (if this does indeed occur), I would think that the thermal conductivity of the gauze also plays a role. The gauze, being made of many tiny filaments, absorbs heat more efficiently than the flat bottom of a saucepan. Additionally, the gauze is made of silver, which is extremely thermally conductive. If the bottom of the saucepan makes good thermal contact with the silver gauze, then the gauze probably acts to slightly boost the rate of heat transfer from the flame to the saucepan. Sort of like the layer of thermal paste between a computer's CPU and heat sink.
  12. Of course, such nets are unnecessary, as vast majority of house ovens don't utilize them and still work fine.

    If it really bothers you: spend those $2.00 and make a test how much (it at all) it improves the efficiency of the burner. Simplest methodology: measure the time needed to bring to boiling the same pot containing some known amount of water at know start temperature. $2.00 is not really big expense comparing to knowledge you may earn.
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