how much LP does a pilot light use (waste)?
(we have a 140K BTU Modine)
Nothing, more or less. A pilot light is about 1-3 BTUs. A pound of propane costs about 50 cents and has over 21,000 BTUs. That 50 cents worth of propane will easily last a year.
I have never bought propane by the pound. Most recently I paid $1.99 for a gallon. How many pounds in a gallon?
I think your pilot useage will be more than the above estimate. I found numbers around 400 BTU/hr, so a gallon of LP will run the pilot for about 230 hrs.
I agree with cottage.
I would guess that pilot lights use about 200-500 btu's/hr
A pilot light is the size of a candle. A candle is 1 BTU. A propane candle is NOT 500 times hotter than a candle, now is it? It might be slightly more, 2-3, maybe 10. 200-500? NO WAY! That's ridiculous...nothing would have pilot lights in the year 2005 if they wasted that much fuel.
While on summer vacation, I checked my gas meter and used an average of 0.5m3 of natural gas a day for just the hot water heater with the themostat turned down all the way. That is about 18,500 Btu/day. My 30+ year old furnace seems to use about 1m3 of gas for the pilot light only. The pilot flame does seem big for the matchbook power pie generator.
Also, note that none of the new furnaces have a standing pilot anymore
What do you mean by a standing pilot light?
Weebus, a standing pilot means a continuously lit pilot; the thermocouple in the pilot light flame generates the microvoltage to hold the valve open and keep the pilot lit.
Both of the brand new Empire heaters I installed last year work in this way. The alternative is an electronic ignition system. However, I view the standing pilot system as superior for GH security, as it is independent of the electrical system. If power goes out, I still have heat.
The link at the bottom cites a pilot light monthly use of 6 therms (600,000 BTU). At our cost of $1.36/gal propane, we're talking about $8.92/month. This is around 800 BTU/hr.
This link that shows 1000 BTU/hr, a little higher: http://hearth.com/articles/15_0_1_0_M2.html
Here is a link that might be useful: Pilot BTUs
Generally anything ending in .gov is an extremely unreliable source of information. Pilot lights DO NOT generate more than a hand full of BTUs. As I said above, a candle is about 1 BTU. That is a fact, google it if you like. Now, go look at a pilot light and compare the heat and light output to a candle. It's about the same isn't it? Why is it then that a candle is 1 BTU and this little gas flame is a THOUSAND times bigger? It's not. Anybody can see that.
I have a 1300 BTU propane heater. This heater puts out enough heat to warm up a small room. Have you ever seen a pilot light heat up a room? Of course not.
That's what I thought. I have 3 propane heaters. I just bought my third one two days ago. It has a 'standing pilot light' So I guess I don't understand.
I have a comfortglow in the GH
An Avalon downstairs and a
If a heater/stove/furnance doesn't have a continuous burning pilot light, how does it fire off each time the room gets down to temperature?
To clarify, a BTU is a measure of energy (Joules in modern units). Heating systems quoted in BTU are actually BTU/h, one of which is about 1/3W. 6 therms per year corresponds to 20W, and this matches up with my experience of the heating power of a pilot light quite closely.
A candle is similar in thermal output, delivering only a small amount of energy as light (1 candlepower = 1W) as candles aren't very efficient light sources. You can read here that the heat output of a candle is from 20 to 111W - a significant amount of energy by any scale!
(It's all very much simpler and less confusing if you use SI units ;)
Canadian government cites pilot lights at 600-1500BTU, see below.
Google of "pilot light BTU" will give you multiple sources, they are all in the same ballpark.
Weebus, in the absence of a standing pilot, the heater ignites with an electronic ignition. An electronic signal ignites the pilot light only when the thermostat call for heat. SB
Here is a link that might be useful: Pilot BTU estimate, Canada
Does it still work without electricity?
Nope. That's what we have for our house and if there's no power there's no heat. That's why we bought a generator a few years ago.
Even at the high end estimate of $10 bucks a month it seems a small price to pay to know your heater will heat when there's a power outage. A not infrequent occurrence in our area.
Junior said it. The standing pilot works without supplemental electricity, as the thermocoupler works like a little current generator powered by the heat of the pilot light. The other electronic ignition systems are dependent on power. I agree with Junior...that's why I said that I like the standing pilot system for my GH...you have heat if the power goes out. SB
JB, Out pilot light doean't cost anywhere near $10 a month in LP. That would be about 7.5 gallons per stove. more like $10 a year...
You guys clearly do not have an understanding of just how much energy 500-1000 BTUs is. 1000 BTUs is a HUGE amount of heat! It takes nearly 1oz of propane per hour to produce 1000 BTUs. That's over a pound per day! Or about $15/month! Nobody pays that! If that was the case the EPA would have banned them completely years ago. Modern appliances are using electronic ignition for convenience, not energy saving.
PILOT LIGHTS USE ALMOST NO GAS! If anyone believes they use more than a handfull of BTUs I've got a bridge to sell you...
JB and Strees, You might have heat with no power but what about the fan? I wouldn't want to run our heaters with out the fan blowing. Would probably melt the plastic above the heater. And would never heat the other end of the houses.
Anywho that's why we have a generator also :)
Standing pilots do blow out. Electonic pilots can have electronic failure. But at least electronic doesn't burn any extra fuel. Regardless of how little. It still adds up over the years.
Good point Mylu.
With these estimates on BTU output do we know what time period is being used? Is it a measurement of the btu's produced over 1 second, 3 hours, one week, a month or a year?
And also there not used over the whole year.
Sorry Cheese, but clearly you have no idea how much energy 1000BTU is. It is about 1 MJ, which is enough to bring about 3 L of water to the boil. I have no trouble invisaging this happening from a pilot light in a day, in fact it seems rather low. If you still have trouble believing this, take an old steel food can (dog food or whatever), one end open, the other end with some holes in it and hold it upside down over the pilot light with your bare hand. It will be similar to holding a 25W soldering iron by the hot end - believe me, I've tried.
And yes, there is a strong push to replace all pilot lights with electronic ignition. (It's a buying requirement in Australia, where heaters only get used for 4 months)
Regarding powerless starts, there are a few solutions to that problem I've seen in commercial heaters. Clearly if you have a blower then you'll want power, but in the case where you're relying on convection or radiation alone I've seen systems with a battery back-up (often a small 1A/hr gel cell). Hot water services here usually use the water flowing through to provide the current to start, particularly the continuous flow heaters. A similar idea can be used for large power heaters - use the gas flow to provide the sparking current. Finally, if starting is essential then you can use catalytic igniters, which use something like divided platinum or a rhodium mesh to ignite a starter flame (but these cost lots and are generally only used in critical systems like in space equipment).
More recently heating systems which generate not only starting power, but enough to run a blower, and everything else and have some left over are now on sale - these are called combined heat and power (CHP) systems, and they burn the gas to run a heat engine (usually a jet engine or a stirling engine). The nice thing is that although the heat engine extracts most of the free energy, what you get left is hot air - exactly what you want for heating a greenhouse. I predict that within 10 years this will be standard for heating greenhouses. (It's already getting wide use in large building heating systems)
I guess I'd better fix up the wikipedia link.
Here is a link that might be useful: wikipedia on pilot lights
That article is rather dated, and it also depends on the type of gas used. On my heater, the NG pilot should be 2-4" long and LP would be 1/2 -1" long. Seems logical that one burns more gas than the other.
I have no idea of how much gas a pilot light burns, but I do know that I turn mine off at the end of the season. Saves the Thermacouple also. Another thing is that the only time a pilot light is wasting energy is when the stove isn't burning. If it is burning, the pilot light is adding to the heat, therefore not wasted. I didn't see that taken into consideration in the article.
My stove is on quite a bit of the time during the cold months. The Comfortglow doesn't cycle on and off like a regular heater, it increases and decreases output as needed. If it gets enough over the setting, then it will cycle off.
Not taking one side or the other, but I have to question those enormous amounts just based on what I use...
Now I have to go research this.
How much is "ALMOST NO GAS!"????
If it burns any gas that is not used to heat your house then it is wasted. How many pilot lights do you think there are in the world burning right now?
Is that "ALMOST NO GAS!" Too?
NathanHurst, you've just proven that you do not know what you are talking about. BTUs are measured per HOUR. That means if a pilot light uses 1000 BTU per DAY, that's only a 41 BTU/hour energy consumption. That is not enough to boil more than a shot glass full of water.
And again, 41 BTU/hour, which is a very high estimate, is almost nothing. Propane has over 91,000 BTUs per gallon costing about $2. That means 41 BTU costs $0.0009 per hour to run. That's right, less than 1/100th of 1 cent. If you can't afford that you have no business owning a greenhouse.
Cheese, I loath to respond, but here is a quote from wikipedia:
"The British thermal unit (BTU or Btu) is a non-metric unit of energy,"
Energy is not power, and you would do well to understand the difference.
"The BTU per hour (BTU/h) is the unit of power most commonly associated with the BTU."
I don't really care whether you think that wasting gas is reasonable or not, I am only interested in facts. You claimed that a candle produces 1BTU/h, I found it was more like 100btu/h; I don't believe you any more.
several sources on the internet say a standing pilot burns about 600 btu.1 gallon of propane contains 90000 btu.at that rate a pilot burns 1 gallon of propane in 6.25 days.OR 4.8 gallons of propane a month-OR 28.8 gallons of propane for my 6 month greenhouse heating season.i paid 1.60 a gallon for propane-so it costs $46 a season-$7.68 a month.BUT,if i didn't have a pilot light,and the power went out at night(which happens a couple times a year here) i'd lose several thousand dollars worth of plants.so 7.68 a month for insurance is cheap.REAL cheap.wish my car insurance was so cheap.and the peace of mind is kinda nice.that said,i may start cutting the pilot light off during the day....
Yeah!!!! This thread is really fun!
"1 gallon of propane contains 90000 btu"
"pilot burns 1 gallon of propane in 6.25 days"
"a pilot light burns 600 BTU/h"
Are we agreed on these numbers?
Can we leave the financial aspects out of this as my propane is $1.29 a gallon (propane costs for 100,000 BTU = $1.44) and electricity is $0.038 per KW/h (electric costs for 100,000 BTU = $1.11)
OK we got this far. Let us now imagine a 150,000 BTU/h propane heater runs for the sake of argument 6 hours a day on average. That is 900,000 BTU fuel used per day.
The pilot light is using 600 BTU/h 24 hours a day which is 14400 per day. Oh make that 18 hrs per day as for 6 hours the pilot light is actually contributing to the heat when the heater is fired up, so... it is actually "wasting" 10800 BTU per day.
The pilot light is "wasting" 1.2% of the energy fed into the heating system.
Now, a propane heater does not run at 100% efficient, more like 97% is the best I can find on the net but 90% is pushing the top end. You just have to squeeze 1.2% more out of your heater to pay the cost of the energy wasted by a pilot light.
Bringing this back to the real world, if your greenhouse were 6 inches less tall the energy savings would be WAY below the 1.2% you could get by not having a pilot light.
Greenhouses suck up money in heating costs. The pilot light is just a flicker compared to the money that escapes out of there in other ways.
This thread is good as it makes us think how best to conserve energy. The pilot light is way down my list but, as stated, it is but one more "waste".
Well written Chris. I agree that for large scale heating the pilot light is completely irrelevant (indeed if the pilot light is only on in the cooler part of the year it actually is not a true waste, as it provides heat which offsets the run time of the main burner).
We should run the same calculations through with a small scale heater, as might be used in a hobbiest in portland: I'm guessing a 20000btu/h heater running for 6 hours a day for 3 months of the year, with the pilot left on all year. This is equivalent to 1/12 duty cycle and results in the pilot light using 36% of the total gas.
So if we want to use a pilot light for reliability (although nobody has given compelling evidence that pilot lights are actually more reliable than other solutions - in my experience they are far more likely to blow out than the battery is to go flat in a blackout) we should try to minimise the number of heaters for the maximum heat. We should also turn them off once the risk of freezing is over.
Having read all this, I can say that I'm very glad to live in a place that never drops below freezing. But then I grow plants that won't drop below 12C...
how much does it cost you when the electricity goes out?
How much does it cost me for what when the power goes out?
I worked in percentages instead of actual dollars because everyone is paying differing amounts for fuel.
I am asking how much money you lose when your plants freeze because the power has gone out. The least expensive isn't always the cheapest...
Oh, I thought this thread was a kind of "How much of earth's natural resources does a pilot light waste"
Well, in answer to your question, it all depends on several factors.
1, How far above freezing was the air temperature when the power went out?
2, How much money are the plants worth?
3, Can your non-powered propane heater with a pilot light still heat your greenhouse when the poly inflation fan quits?
4, How low a temperature will the area furthest away from your heater get without a circulating fan running?
If you have a significant investment in plants and the structure cannot ride through a power outage of a few hours then I suggest you get a generator.
On the topic of pilot lights "wasting" energy I just went down into the basement and took the cover off the furnace. Electronic ignition. The 24v transformer is warm to the touch and so is the Honeywell high voltage spark unit.
If any enterprising soul out there has a "kill-a-watt" meter maybe they can measure how much an electronic ignition heater is "wasting" while in standby.
Here is a link that might be useful: Kill A Watt
refiguring my figures....well,ALL my figures must be cut in half,since,as nathan stated,the pilot is providing some heat at night,so this is not "wasted".2.4 gallons a MONTH,or 24.4 gallons for the 6 month season.ok,ok,ok,i'm leaving $ out of this one...what do you all do when the power goes out?my greenhouse is twin polycarb,so i don't have a blower.but i do have 3 fans circulating heat.i keep the greenhouse a little over 50f.without the fans,there are afew cool spots-but i still keep it far above freezing.i'd hate to lose everything in february,after babying them all winter...this leads me to want to start another thread...the dreaded power outages....ice storms..
Laughing, until last week I didn't have a double layer of poly either, and as for an inflator fan then I am going to buy my wife a $14.95 inflating Santa for Christmas... (Guess what will happen to his inflating thingy on the 26th!)
I run what I do with no, or very little electricity or supplimental heat. For two reasons.
1, I am doing what I do as cheap as I can because I really do not have any money that is surplus. (the $182 for the 4 year poly was a MAJOR investment)
2, I live in a place where a prolonged power outage is expected. It is normal, and everyone plans for it.
As this thread is about "waste" then I could make quite a few enemies by saying using non-renewable energy to heat a greenhouse in a hostile climate as a hobby just because you have enough money to buy the fuel is a criminal act.
There, I said it........
Growing stuff in a zone where that stuff should not be growing is really fun as a hobby. If you throw money and energy at the problem it is easy. If you grow stuff in a zone where it is not supposed to grow and you do it without cheating (throwing money and fuel at the problem) then it turns from a hobby into a sport.
P.S. the furnace in the basement quit working after I took a panel off to look at the electrical stuff... There is a microswitch that makes sure that all the panels are on before it does its scary burning thing.....
:) Fixed it!!!!!
Well said Chris. I think you are right on about the challenge of doing stuff out of zone. I grow things from alpine to tropics in my unheated greenhouse. I had a long look at myself when I put an electric blanket underbench heater in to improve my cutting strinke rate. If people are trying to grow cocao in north dakota using only sunlight then I'm impressed. If they are doing it at the cost of changing my climate then I see self-centred conspicuous consumption.
Has anyone here tried the idea of using decomposting straw to heat their greenhouse? I remember reading smoe years ago of a family that met their hot water needs in some cold place for the whole year using a 5mx5mx2m straw cube with polypipe run through it. The total cost was something like $100 for the straw and at the end of the year they had pile of rich black soil.
yep are we treading on dangerous ground now.
I can understand, and agree with using non-renewable resources to grow food in areas where the fuel used to transport that food is greater than the amount used to produce it locally.
The straw decomposing example you mentioned.
For the non metric in here 5mx5mx2m is 15x15x6ft (and a bit) whch is 1350 cubic feet (and a bit more) Now, you stuff that much straw into your coldframe and you run poly pipe through it (100ft of not NSF 1/2 inch is around 6 bucks) and it composts. Do not take all the heat it generates as the bacteria needs warmth to survive. Even if you do not use the heat generated you used your structure to make something you can use. Compost!.
Feel better now that you have taken some pot shots? No need for it here. I don't need to explain why I do what I do, but rest assured, and sleep well at night, knowing that your good friend on the GH forum is very much an environmentalist. Almost to an extreme. Hot water on demand, composting toilet in my shop, energy saving lights and appliances, faucets with valves that I cna turn off while soaping up, and I am designing a grey water system for my garden and I drive a Prius (2005). If you don't know what that is, look it up and feel better about your world. So, not only do I preach a cleaner world, I put my money where my mouth is. I could point out several things you do that are not environamentally friendly, but that isn't what this forum is about, is it.
I do think it is quite ironic the two posters, who are swearing on their numbers, Both donÂt use heat.
Makes you want to say Hmmmmm.....
Very observant on the fact the electronic ignition is still using energy when off. That puts a whole new twist in the discussion....
It's always interesting when the original poster has no idea what they have started!
Yes, it seems amazing that two posters that do not use supplimental heat without carefully considering it are adept at using the numbers.
Sometimes using the numbers helps you to understand what you can, and more importantly, cannot realistically do before you waste time, money and energy trying it.
Oh weebus, Some of us are trying to put the "green" back into greenhouse.
Hey I got those coiled light bulb things too, (takes about 5 minutes before they get to full brightness though, ain't that a pain sometimes)
I already have a grey water system, but don't ever make pum'kin pie out of any pumpkin I give you.....
Ya got me on the faucets with a valve, but seeing as I only take a bath once every three weeks (whether I need it or not) then them faucets ain't something I looked into.
Oh I don't have a car. I either walk, ride my bike or bum a ride to the big city when I have a need to go there.
Seeing this thread has answered the question "how much LP does a pilot light use (waste)?" I would be quite interested in knowing the several things that I do which are not environmentally friendly.
You point out those things and not only will I realize where I need to try harder, other people will learn.
"electronic ignition is still using energy when off."
Yeah, and so is your TV, and your VCR and your computer.
This trying to do greenhouse growing stuff as a sport makes you think in wierd ways.
Get off your self righteous horse. You have no idea of who I am or what I do, even in my GH. Stick to Greenhouse discussions, you look a little less foolish.
Missed the part of your post where you told me the things I do which are not environmentally friendly.
I really don't want to get into this, but since you won't let it die, here's a couple off the top of my head
1. you recommend using regular plastic on a Gh instead of spending the money and getting the proper equipment. Not only is it a waste to use regular plastic, but wasting so much plastic and filling the landfills with it is not environmentally friendly. I covered my GH and won't have to re-cover it for 15-20 yrs. or more.
2. You suggested using a hoop house inside an unheated GH. Again, a waste of plastic and redundant. If you would just grow the right crop to fit the environmental conditions, the extra materials wouldn't need to be wasted.
We all do things that are not the most efficient. If it is done one way, it wastes in another. NO ONE HERE is the most environmentally friendly (EF), or we wouldn't be using these monitors with lead and copper in them, but hopefully we use them to educate ourselves on other ways to be EF.
Now, even though it isn't any of your business, I grow plants to donate to the college plant sale to raise money for scholarships, for the horticulture dept. I also do germination testing for Native species of the PNW, so we can learn how to better propagate natives and hopefully deter people from "Wild Picking" them. I give away what I grow, because the 'SPORT' in it for me is to get the seed to germinate and grow into a healthy plant, especially when everyone else has failed. I also grow some veggies in there so I don't have to buy them from the store who gets them from some guy who nukes his soil to kill disease and sprays pesticides to kill all the pests and beneficial insects. I don't feel the need to apologize for being able to afford to heat my GH, but I am using the least amount of propane as possible by buying a efficient heater, having a well insulated house and postioning the GH so that it gets the most benefit from solar heating. You save the earth your way, I save it mine.
Now can we all get back to GH and helping people help themselves?
Regarding commenting on heating when I don't heat - that is because I worked out that I don't need to heat. Plenty of people in Melbourne do heat because their design is weaker. The best solution for minimising heating energy cost is to make the greenhouse as big as possible, so rather than advocating each person grows their own, I'd suggest each area has a large scale greenhouse for food (or grow food outside if possible - it tastes better!). Also, having a degree in physics is helpful ;)
What did you use that lasts 20 years on the greenhouse? Glass has a huge energy cost, and Lexan produces far more toxins in manufacture than even PVC. I bet that 5 lots of PE has far less environmental impact than either. I, of course, use PC as I like the look :-P
Interestingly, I do pretty much the same as you only for natives of my area, for pretty much the same reasons. What genus are difficult to propagate, and why? Have you looked at tissue culture? I've propagated some otherwise fiendishly tricky species quite easily with meristem cloning. Also, there is a chemical discovered in W.A. that causes almost any seed to germinate.
p.s. we use LCDs here ;) Have done so for about 5 years.
Glass has a huge energy cost, and Lexan produces far more toxins in manufacture than even PVC. I bet that 5 lots of PE has far less environmental impact than either. I, of course, use PC as I like the look :-P
I'll take that bet. Don't forget ALL the costs, not just the manufacturing. There is not only the manufacture of the PE, but the manufature/refining of materials to make the PE, transportation costs of the materials to manufacture the PE, the transportation of the PE to a distributor once it is manufactured, the transportation to a retailer, the transportation to the end user, then once it is used, it must be disposed of, and transported to e disposed of. This isn't taking into account the refining of the petroleum products to transport the PE etc...
See, it can get gnat's bottom, and almost to the point of absurd. Instead of playing the game of "I am more EF than you are." Let's try and educate each other on how to be more efficient with what we do, becuase everyone's circumsatnces are different. I don't believe that other's designs are weaker than yours, I believe their circumstances are different and their design meets their needs.
As far as germination of natives, the problem we have here is trying to duplicate their native settings. They are mostly herbaceous and a soft coated seed. Some of them need to go through 2 stratifications, some need heat (like a forest fire), others need scarification (VERY few). we can get them to germinate, but not readily and no one is growing enough, or doing enough research to keep up with a growing demand.
I think you are dealing with more hard seed coats aren't you? I am linking an article a friend of mine wrote that may be of interest to you...
Here is a link that might be useful: Seed percussion
I DID use regular construction plastic for two full seasons, and I if you are following the story I just installed a double layer of Tufflite IV. I used regular plastic to begin with for three reasons.
1, $30 instead of $140
2, I was not sure a greenhouse here was a good idea. (if you notice my "structure" is a little bit taller than your average wood framed structure of that type. If the greenhouse idea did not work it is a machine shed)
3, I had grave doubts that poly covering would stand up to the wind in this area. Cornstalks are a problem in the fall.
On the subject of building a hoophouse in a greenhouse, my hoophouse holds 32 x 288 plug trays which starts me 9216 plants. Under the benches goes 360 gallons of water. That plastic is in use for 5-6 weeks a year, it should last me another 5 years or so. As the average temperature gets higher and the plants are transplanted they then fill the rest of the greenhouse. Simple!
Now, if someone would like to donate several thousand dollars of triple wall to the noble cause then it will be gratefully accepted.
wow,we've now got 48 posts here.can we get it to 100 posts.without someone having a stoke??????lol.anyhow,when i saw my pilot light burning tonight,i thought about it.it's burning right now.the plants are looking awesome!the angel trumpet cuttings have several inches new growth-and the hot peppers are recovering from the garden uprooting,and putting on new leaves!come on hot peppers!i'm always trying to figure out new ways to save fuel,as well as increase my plants health!it comes down to enjoyment of this piece tropical paradise-with cold winds howling outside!WOW!
""with cold winds howling outside!""
Yeah, well a "cold wind" in Georgia is what we in Iowa go outside in to dry off after a shower so we don't muss up a clean towel!
Happy thanksgiving!!! (expected high here Thursday of 29F high low of 10F, already had a few 4Fs)
Just a different 2Â¢,
I have a gas stove, This is pilotless, While replacing the computer in the stove ($200 part $75 labor) I asked the repairman how much pilots cost to run, He said $8 to $10 per
year. So now I am looking at about $150 per year for a computer vs $8 to $10 worth of gas. My savings are ?
Perspective: I don't know about LP gas but I use a 10,000 BTU kerosene heater. It runs 12 hours on about 1 gallon of K1 (6 p.m. - 6 a.m.)which is $.23 per hour. That means it outputs about 120,000 BTUs on one gallon for about $2.75 US. That comes to $.0000229 per BTU. K1 kerosene is 2 times more expensive than LP. I think the pilot light cost is negligible. I spent two winters in the Phoenixville - Pottstown area. It can get really cold. That cost sure beats going out in the cold, snowy Pennsylvania night to light the heater.
Thanks for clearing that up Byron, kinda what I suspected but didn't know for sure
I know we're all sick of this discussion, but someone just pointed out to me on wikipedia that the original estimates of 20W were out by a factor of 10, i.e. 200W-500W. The original article had a typo and was corrected in a later edition. The wikipedia article has links to 2 different documents that agree to within a factor of 2 that the annual gas usage is about 100 therms, or about $80 a year. Personally this seems way too high, but I can't find any stronger evidence elsewhere. (The fact that the heat isn't actually wasted in heating a greenhouse, unless you are trying to cool, still applies)
Here is a link that might be useful: wikipedia pilot light article
That does sound a bit high. I get 166 heating days (Nov. 15 to Apr. 30) or 17 1/2 gallons of propane (and thats probably somewhat less than reality). Propane is selling for about $2.80 a gallon around here so that would be about $48 for the heating season to run the pilot on my heater. It must be nice to get natural gas for .80 a therm. They have managed to drive the price in the Midwest up to $1.40 a therm!
Pass the popcorn...this thread is GOOD!!! LOL
The research is from a decade ago (1997).
jaxjeep, if the pilot light really does produce 500W of heat you'll be able to cook popcorn on it easily.