Propane Pilot Lights

[MountainDon]

Does anyone know approximately how much propane the average pilot light on a water heater or furnace or oven range uses over any particulat period of time?  Pounds, quarts, BTU / hour, day, week......      It's easy to find usage for the appliance when the burner(s) are going, but nothing I've found on just the pilot light.

[Shawn B]

http://www.builditsolar.com/Projects/Conservation/PilotLights.htm   <see below>
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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.

[considerations]

I seriously think that they use very little.  I have a 100 gallon propane tank supplying the 5th wheel.  Last time I filled it was January.  I've kept the thermostat at 55F, and the pilot lit on the water heater.   The gauge is at 30% and was at 96 when it was full.  The summer was cool and spring was wet and cold....till July - meaning the furnace was working some from January until now.   

Found this on the web:
"It depends on the appliance we are talking about, but for a fireplace or average furnace a pilot is about 1000 btu's...So when you consider that 100,000 btu's burns a gallon an hour...It'll burn a 20 pounder in a little less than 90 days.
Not very much!
Source(s):
20 years experience in the propane business"

[glenn kangiser]

I have heard around $60 per year a couple years ago.

[MountainDon]

From more searching that I've done I do believe there is a considerable variance between pilots. I believe the RV water heater pilots use very little compared to regular house appliances.

If/when I can find my adapter that allows me to connect a 16 oz disposable cylinder at the RV tank connection, I'm going to run a test on the RV water heater. That's the one I'm mainly interested in as it is the same heater that I used in the cabin.

[Dave Sparks]

Yes there is a variance in how the flame is adjusted. Sometimes they are over tweeked and use more to avoid a flameout from wind. The new gas water heaters have sealed combustion and it is just about impossible to blow one out. The one I reccomend from American has the loops in it for radiant, space, or solar. We turn it off for 9 months each year and really can not tell any difference in cost from the pilot because of the huge cost from not burning any propane due to solar heated water.

I am doubting that an RV pilot uses less for the above reason though Don. Some of the adjustment procedure use to tell you to try and blow out the pilot when setting the pilot flame height.

[MountainDon]

Sorry I messed up a tad.... double posted this. Put it in the wrong place first.   



Okay now, FWIW the propane pilot test happened this weekend. I started the Suburban brand RV water heater, 6 gallon, Saturday afternoon. The control was set to allow only the pilot light to be lit, no main burner. I had a 20# tank hooked to one side of the changeover regulator. The other side had a Coleman disposable cylinder hooked up with an adapter. At 4 PM Saturday I switched the regulator to the disposable cylinder. Monday at 2 PM I switched the disposable cylinder out of the system and removed it.

The disposable cylinder weighed 304 grams less at the end of the test.
304 grams for 46 hours of operation = 6.608 grams per hour.
6.6 X 24 hours = 160 grams per 24 hour day.
I'm going to round that up to 175 grams per day.

175 per day X 30 = 5250 grams per month; 11.57 pounds per month

At 4.24 pounds of propane per gallon that would be approximately 2.75 gallons.

So one of my 40# portable tanks should last about 3.6 months if feeding only the RV water heater on pilot light only.

[bayview]

   Wow!

   That makes a good case for buying a DSI (Direct Spark Ignition) electronic 12v water heater.  We have one in our travel trailer . . . It has a quick recovery and we turn it on about 15-20 minutes beforehand.   It has a 6 gallon tank and is made by Suburban . . .

/.

[MountainDon]

What would make an interesting test comparison would be to meter how much propane a direct spark ignition water heater like yours uses to provide the hot water for two people for a 24 hour period. Interesting because I've used the RV pilot light water heater on pilot only for years. Seldom, once the water is heated, is it ever necessary to turn the control to allow the burner to fire up. With the extra insulation on the tank (2-3inches foam) the water is at 150 degrees F in the morning. Unless we take a long shower (a quickee 2 gallon max is my norm) the water temperature never falls "too low". More often than not cold has to be mixed to make it bearable to stick a hand in the flow from the faucet.


For those who do not know, the direct spark type has no pilot. When the tank thermostat calls for heat the valve opens and the burner ignites from the ignition spark. Then the burner turns off when the set temperature is reached.

[bayview]

   Your heater probably is pretty efficient . . .     - Heating with just the pilot light.   

   Our DSI, of course heats only when on.  Its efficiency depends on the water being admitted.   We are hooked up by a garden hose.   At times in the summer when its 100 + outside, the hose is hot enough for showers, etc without turning on the heater.   But on the other hand, in the winter we may have to raise the temperature 80 degrees,   

   So, I guess there are a lot of variables . . .

   What does it cost to refill your 40#?   We have 2 - 30# on our trailer.   Refills are $17 ea.

/.

[MountainDon]

$2 a gallon for the past several months