Gas Pilot Lights

Some thoughts on gas pilot lights.


Pilot lights are used on some natural gas or propane appliances (water heaters, dryers, fireplaces, stoves, ...) to light the main flame.  These pilot lights stay on 24/7 to light the main flame when required.  While most modern gas appliances use some form of electronic ignition instead of a pilot light, there are still many appliances out there with pilot lights.


Various sources report that a pilot light burns from 5 to 12 therms of a gas per month depending on the particular appliance and how the pilot is adjusted.  At $1.50 a therm for natural gas, this would be $7.50 to $18 per month per pilot light.  For $2 per gallon propane, it would be about $11 to $26 per month! 

So, there is a definite cost associated with a constantly burning pilot light.


A constantly burning pilot light also adds heat to the house.  Using the numbers above, a pilot would add about 17,000 to 40,000 BTU per day to the house.  This heat can be useful in the winter when it helps to heat the house, but, in the summer it just adds to the unwanted heat load, and makes the house hotter or requires more AC on time.  Even in the winter, the appliance may be located in an area of the house (e.g. a utility room) that you really don't care about heating, so the pilot light energy is largely wasted.

The article from Do the Math in the links below shows a simple way to measure your pilot lights gas usage using your home's gas meter. If you do this, I'd like to hear how it comes out.



Some strategies:

Some people may pay a minimum gas bill that covers the cost of a pilot light in the summer, so they feel there is no benefit to turning it off.  This is bad bad logic.  The pilot adds heat to the house all summer when you don't want heat, and running a pilot light for 6 months unnecessarily will generate about 450 lbs of CO2. 



A Pilot Light Water Heating Strategy

This is kind of amazing.


Don, who runs the website, has his gas water heater set up so that the main burner cannot come on.  In his case, the pilot light alone heats all of the water needed by 2 people.   He goes a step further, and does not vent the hot water tank to the outside, and actually restricts the water heater flue passage so that less heat is lost by convection through the flue opening.  The justification for doing this is that the pilot light alone is no larger than the pilot light on a stove or gas refrigerator, and these are safely run without and outside vent.  While I don't see anything wrong with this logic, I'm not sure I would go this far, as it seems to be getting a bit close to the boundaries of safety.  But, it is amazing to me that a standing pilot light can supply this much hot water -- it gives some feel for how much energy a pilot light wastes.


Here is a link Don's description of the system, and how it has worked out:


Any thoughts on this?  email me Gary


How much water should you be able to heat with just a pilot light?

If you take 6 therms per month as the an average pilot light energy use:


    Energy per day = (6 therms/mo)(100,000 BTU/therm)(1 mo/30 days)  = 20,000 BTU/day


    20,000 BTU per day is enough to heat about 30 gallons of water from 60F to 120F assuming 75% efficiency **


Here is an article from Pandscorp that provides more detail on the ins and outs of heating water with a pilot light only...



More Pilot Light Information

Nice calculator for Natural Gas appliance energy use and cost, including pilot lights:
There estimate for pilot lights is 2.6 therm per month -- somewhat lower than the others.

From the "Do the Math" website, some actual measurments.
This is quite a good article -- it shows you how to use your gas meter to determine how much energy your pilot light(s) are using.


This is a short article published by the Cornell Energy Conservation in Laboratory stating that pilot lights consume more that "Pilot lights waste over 20 percent of the gas used in the United States.": 

Energy Conservation in Laboratories

By Tom Shelley, Cornell Environmental Health and Safety
Prepared August, 2004; last revision on Dec. 7, 2005

Laboratories are well known to be energy intensive facilities, consuming many times the energy use of the average non-lab academic building.   Labs use large quantities of heated and cooled, one-pass air for ventilation and fume hoods; electricity to operate fans, lighting, and an enormous variety of specialized lab equipment; and water and process chilled water.  Some lab facilities also use substantial quantities of natural gas. 

For many years it has been assumed that lab building were always going to be expensive to operate.  In the early years of the 21st Century we have experienced substantial, rapid increases in energy costs and an increased consciousness of the pending scarcity of natural resources and our responsibility to be good environmental stewards.  Reduction in energy use results in more responsible resource management and pollution prevention while avoiding staggering energy costs. 

Many improvements to facility design, including the computerized control of lab buildings, have lead to very substantial energy savings in recently constructed lab buildings.  However, many of these energy saving improvements are only fully effective if the people working in the labs"the end users"are involved in the energy conservation efforts.  There are many things that you can do as both a laboratarian and energy consumer to reduce the overall consumption of energy in your lab:

  1. Turn off the lights when you leave for the day or for a meeting mid-day, especially if your lights do not have a setback (turn off themselves after a few minutes).
  2. Turn off all electrical equipment, when possible, when you leave for the day.
  3. Use timers to turn other pieces of equipment on and off.
  4. Turn off your computer's monitor when not in use.  The monitor consumes over half of the energy used by the average computer.  Even if you can't turn it off, always set your computer's energy savings features to put your computer and monitor "to sleep" after 10 minutes which cuts power use nearly to zero.
  5. Close the sash on your fume hood, especially if you have a VAV type fume hood.  A typical five foot hood uses $5000 per year in heating/cooling, closing a VAV hood sash can cut the air volume and cost by two thirds!
  6. Promptly report room comfort conditions that are not normal.  Rooms that are too hot or two cool may be due to faulty thermostats or other controls that are malfunctioning or have drifted from set-points resulting in wasted energy as well as uncomfortable conditions for you.
  7. Report drips of water from sink taps, chilled water connections or RO faucets.
  8. Buy energy efficient equipment.  Look for the Energy Star logo or other statements that an electrical device is designed to be energy efficient.  Each 1000 watts costs  $850 per year in electricity.  If the extra cost of a "high efficiency" unit can be paid for in 5-7 years or less, that is what you should choose.
  9. When purchasing natural gas powered or consuming devices buy equipment that uses an electronic ignition instead of a pilot light.  Pilot lights waste over 20 percent of the gas used in the United States. 
  10. Use shades and blinds as provided to help keep your space cool on sunny days.  The shade can reduce your peak cooling load in a south or west facing room by over 30%

Reductions in energy consumption save the University money and frees up those funds to be used for other areas of research support.  Each of us can do our part and what we do matters.




** The Calculation:    If the water needs to be heated from 50F to 110F, then 20,000 BTU would heat:


    Water per day = (20000 BTU)(1/(110F-50F) (1 /1 BTU/lb-F) (1 gal/8.3lb) = 40 gals per day at 100% efic


    If the efficiency were 75%, it would heat about 30 gallons per day.



Gary  5/28/07, May 4, 2008