Gas Fireplace - Shut off pilot light during warm months??

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Saluki31
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Gas Fireplace - Shut off pilot light during warm months??

Post by Saluki31 » Wed Dec 15, 2010 1:53 pm

Does anyone with a gas fireplace turn off the pilot during periods of non-use? The person who installed ours said to leave the pilot lit year round, regardless of use. He said it would prevent moisture from rusting out the unit over time.

We live in the midwest - so we get all seasons. We really never use the fireplace due to a strong odor that is emitted after the fireplace has been on for more than 15 minutes or so. The smell is likely due to the glue in the mantle heating up. Not much we can do about it. Thus I'd like to turn the pilot off year round, but am worried about rusting.

Anyone knowledgeable able to offer an opinion?
Thanks!

TranceLordSnyder
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Post by TranceLordSnyder » Wed Dec 15, 2010 2:02 pm

Do you know what gas smells like? The actual gas doesn't smell, but there is an additive put in so you can smell if there is a gas leak. I would get a propane and natural gas detector just to make sure you aren't leaking anything, or turn off the gas from your tank or main.

I shut off my pilot light once the weather warms up and turn it back on when it's cold enough to run the fireplace again. I don't see any signs of deterioration. My opinion is, it costs to leave the pilot light on and it's not very environmentally friendly to keep burning gas. I don't know what the right answer is though.

Nowizard
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We have three of them:

Post by Nowizard » Wed Dec 15, 2010 2:05 pm

One is on an outside patio, two are in the house. I leave the pilot on for the one on the patio due to possible moisture, but not the ones in the house itself. No problem other than you have to bleed the line for a few minutes when lighting the pilot in the fall. Some have said the same thing about pilot lights for central heating units for years, leave them on, but newer units have no pilot light and there are no problems.

Tim

carolc
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Post by carolc » Wed Dec 15, 2010 2:22 pm

I have two propane stoves. One in the living room and one in the sunroom. I turn both off during the warm months each year because I don't want the additional heat added to the house (especially on those 90 degree days).
Haven't noticed any problems with rusting.

carolc

Atilla
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Post by Atilla » Wed Dec 15, 2010 2:29 pm

It's plenty humid here in the summer. I have always turned the gas fireplace pilot light off during seasons of non-use. Never noticed any rust when I relight the thing in the late fall.

Instructions don't have any kind of warning about rust either.

livesoft
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Post by livesoft » Wed Dec 15, 2010 2:35 pm

Not for the fireplace, but we turn off the pilot light of our furnaces in the months we will not be using them. If we don't use the furnaces, but we leave on the pilot lights our gas bill goes from $20 a month to $40 a month.

Our gas log fireplace does not have a pilot light.

idahospud
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Post by idahospud » Wed Dec 15, 2010 3:34 pm

We have a big propane heater unit to warm up the house (rural central Idaho) and a propane fireplace for the sun and computer room.
The wife and I have had a longstanding disagreement of how we should handle the pilot lights during the summer.

I am looking for a consensus agreement from this wise body of boglehead posters. Don't disappoint. :wink:

jstat
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Post by jstat » Wed Dec 15, 2010 3:43 pm

We turned off the pilot light during the summer for the first couple of years and the insert started to rust. There was noticeable condensation on the interior of the glass front during the summer months.

We repaired the rust, and have since left the pilot light on year round. No rust, no condensation.

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LonePrairie
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Post by LonePrairie » Wed Dec 15, 2010 5:00 pm

When I had a technician here to service the natural gas fireplace in my living room, he told me to leave the pilot light lit all year round. He said it doesn't use much gas and leaving it lit prevents rust and keeps out mice.

BamaFan
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Post by BamaFan » Wed Dec 15, 2010 5:37 pm

We always turn our pilot off when not in use. We have been doing this for 10+ years with no probelms.
"Have a plan, work your plan and plan for the unexpected." Bear Bryant

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Bylo Selhi
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Post by Bylo Selhi » Wed Dec 15, 2010 5:39 pm

In case safety is an issue, i.e. that the pilot might go out, make sure that your fireplace has a feature like this (from the owner's manual of our fireplace):
For your safety, this appliance is fitted with a flame supervision device which will shut-off the gas supply if, for any reason, the pilot flame goes out. This device incorporates a fixed probe, which senses the heat from the pilot flame. If the probe is cool, the device will prevent any gas flow unless manually lighting the pilot.

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SpringMan
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Post by SpringMan » Wed Dec 15, 2010 5:53 pm

We leave our gas logs fireplace pilot on all the time. The installer recommended this because of condensation and also because it may prevent an insect from getting in there and clogging things up.
Best Wishes, SpringMan

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fandango
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Post by fandango » Wed Dec 15, 2010 7:11 pm

We have had gas logs for 20 years in two homes.

We have always turned off the pilot lights in the spring and then relit them in the fall.

We have had no problems with doing this.

rfburns
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Post by rfburns » Wed Dec 15, 2010 7:45 pm

I'll go out on a limb here.

This falls under old wives tales and myths. An old thought back in the early days of central air conditioning was that pilots in the old clamshell heat exchangers should be left on year round to prevent condensation from forming on the inside of the exchanger since cool air would be drawn past it in summer. Made sense, but any evidence of truth was always anecdotal.

Prevention of condensation was the point. But how would a gas fireplace produce condensation with the pilot turned off? It would have to be quite cold and come into contact with warm humid air. If the fireplace is room temperature or warmer condensation cannot occur.

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mephistophles
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Post by mephistophles » Wed Dec 15, 2010 7:54 pm

Saluk,
The gas guy told us we need never turn off the pilot light in our fireplace, so we don't. My brother in law thinks I am nuts and should never leave it on. He is a poor millionaire who only burns one bulb in his house at a time at night so I take his advice with a pound of salt.

jstat
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Post by jstat » Wed Dec 15, 2010 8:21 pm

But how would a gas fireplace produce condensation with the pilot turned off? It would have to be quite cold and come into contact with warm humid air.
In my case the fireplace is in a cool (air conditioned) basement room. When it is very hot and humid outside, moisture would condense on the inside of the fireplace glass. I live in Maryland, where hot humid summers are the norm, and the basement tends to get overcooled.

If we used less AC, or it didn't get as hot outside, my guess is the condensation problem would be much less.

rfburns
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Post by rfburns » Wed Dec 15, 2010 8:53 pm

jstat wrote:In my case the fireplace is in a cool (air conditioned) basement room. When it is very hot and humid outside, moisture would condense on the inside of the fireplace glass. I live in Maryland, where hot humid summers are the norm, and the basement tends to get overcooled.

If we used less AC, or it didn't get as hot outside, my guess is the condensation problem would be much less.
Ahh. Maybe the chimney flue is still open? There should be a manual damper for you to close. If not, crack open the glass doors enough until the moisture disappears.

jstat
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Post by jstat » Wed Dec 15, 2010 9:17 pm

Ahh. Maybe the chimney flue is still open? There should be a manual damper for you to close. If not, crack open the glass doors enough until the moisture disappears
My gas fireplace is a sealed unit with an external vent, so no doors and no damper. I agree that if it was gas logs in a regular fireplace it wouldn't be a problem, since I have never had condensation on the glass doors of my old-fashioned wood burning fireplace.

Saluki31
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Post by Saluki31 » Wed Dec 15, 2010 9:24 pm

TranceLordSnyder wrote:Do you know what gas smells like? The actual gas doesn't smell, but there is an additive put in so you can smell if there is a gas leak. I would get a propane and natural gas detector just to make sure you aren't leaking anything, or turn off the gas from your tank or main.

I shut off my pilot light once the weather warms up and turn it back on when it's cold enough to run the fireplace again. I don't see any signs of deterioration. My opinion is, it costs to leave the pilot light on and it's not very environmentally friendly to keep burning gas. I don't know what the right answer is though.
I do know what gas smells like, and fortunately it's not gas. The smell originates after the fireplace is on for 20 minutes or so. It is bad enough that we don't use the fireplace because of it. We had the installer come out and inspect it. He said everything is in working order. The smell might go away after a long burn in. It has not. He said it could be glue in the mantle that heats up and gives off an odor. Regardless, we never use the fireplace because of it.

Since some others have experienced rust and condensation, I guess I'll leave the pilot lit. I don't like paying for gas usage, considering we never use it. But, I guess that's better than the whole thing rusting out.

Thanks for everyone's input!

zinnia
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Post by zinnia » Thu Dec 16, 2010 12:36 pm

I too was advised to keep the pilot on 12 months a year. One of the reasons I was given is when turned off for a period of time, spiders are attracted to it. They clog it up. The technician said half his calls in the fall are for gas logs that won't light and most times it's spider .

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Stuart01
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Post by Stuart01 » Thu Dec 16, 2010 12:42 pm

Our fireplace guy also recommended leaving the pilot on. We had a clogged up orfice (probably due to a spider?). Now leave it on and no problems.

Glad it is working at the moment! Baby, its cold outside!!

Cheers! :lol:

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FrugalInvestor
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Post by FrugalInvestor » Thu Dec 16, 2010 12:58 pm

I turn the gas off to my fireplace when not using it. I've never had a problem with rust or insects, but that's not to say I couldn't. Each fall before regular use I remove the front glass to clean it - it takes about 15 seconds to remove or replace the glass. I suppose if a bug had gotten in I would clean it out then.
IGNORE the noise! | Our life is frittered away by detail... simplify, simplify. - Henry David Thoreau

matt
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Post by matt » Thu Dec 16, 2010 1:43 pm

Saluki31 wrote:I don't like paying for gas usage, considering we never use it. But, I guess that's better than the whole thing rusting out.
May I ask the obvious question of why you feel the need to preserve something that you never use? Considering that there may not be a potential rust problem at all, this seems like an expensive choice to make.

Saluki31
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Post by Saluki31 » Thu Dec 16, 2010 1:56 pm

matt wrote:
Saluki31 wrote:I don't like paying for gas usage, considering we never use it. But, I guess that's better than the whole thing rusting out.
May I ask the obvious question of why you feel the need to preserve something that you never use? Considering that there may not be a potential rust problem at all, this seems like an expensive choice to make.
Our house is around 6 years old, so everything is in good condition. If we move in the future, I don't think a rusted out fireplace would be a very good selling point. Thus I don't want to risk any potential damage.

adavidso
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by adavidso » Wed May 09, 2018 7:53 am

I can confirm that the rusted pilot happened to me in a basement fireplace that is a sealed unit to the outside.

Location is eastern Ontario, so during the hot summer months hot humid air from outside can enter and condense in the unit due to the cooler basement temperature. I had been in the house 6-7 years, and the fireplace is around 12 years old. Napoleon, fairly basic model.

When the technician cleaned it, he gave the advice to leave the pilot on all summer.

That said, the service call was $80, so I will be turning off the pilot as I think that it is less expensive to have an $80 service call every 4-5 years than burn the pilot all those summers, if you include the additional summer A/C load. In any case I will be due for a call in 5 years anyway, and maybe even a replacement pilot assembly. Maybe I can retrofit an electronic pilot assembly at that time.

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FrugalInvestor
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by FrugalInvestor » Wed May 09, 2018 9:33 am

adavidso wrote:
Wed May 09, 2018 7:53 am
I can confirm that the rusted pilot happened to me in a basement fireplace that is a sealed unit to the outside.

Location is eastern Ontario, so during the hot summer months hot humid air from outside can enter and condense in the unit due to the cooler basement temperature. I had been in the house 6-7 years, and the fireplace is around 12 years old. Napoleon, fairly basic model.

When the technician cleaned it, he gave the advice to leave the pilot on all summer.

That said, the service call was $80, so I will be turning off the pilot as I think that it is less expensive to have an $80 service call every 4-5 years than burn the pilot all those summers, if you include the additional summer A/C load. In any case I will be due for a call in 5 years anyway, and maybe even a replacement pilot assembly. Maybe I can retrofit an electronic pilot assembly at that time.
According to an article I ran across you are definitely correct about the cost trade-off.....

From article:
The big questions that people are usually wondering about is how much gas does it use. Really, it is “how much to it cost per month for the pilot to run?”

You need to understand that most Gas Fireplaces have pilot’s which use about 900-1100 BTU/hr. This is pretty powerful, and for good reason. The pilot must generate enough Millivolts of electricity to open and close the gas valve. This also means that it uses a fair amount of gas.

For a natural gas home, you pay for you gas by the Therm. A Therm = 100,000 BTU. So if you your pilot uses 1,000 BTU/hr and it is running for 24 hours a day, and 30 days a month, that comes out to be about 720,000 BTU. Divide that by 100,000 BTU to find the amount of Therms it uses (approximately 7.2). Then look at your gas bill and find out what you pay per Therm. Usually it is $1 and change. So your pilot can be costing you $7 to $10 per month.
Full article here:
http://www.andersonfireplace.com/news/u ... the-summer
IGNORE the noise! | Our life is frittered away by detail... simplify, simplify. - Henry David Thoreau

barnaclebob
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by barnaclebob » Wed May 09, 2018 9:40 am

The pilot light in our previous house's fireplace cost $10-$15 a month in gas to run, about the same as the hot water heater in summer. I turned the pilot off for the first time the summer after we got a gas stove and our summer bills went from ~$40 to ~$30. Relighting them can be a bit frustrating because you have to hold the safety in until the sensor heats up which can take a few minutes.

New house we don't use the gas fireplace because it was still smelling terrible after 2 hours and the flame pattern was terribly ugly, must have been an older system. We turned the gas fireplace off and don't plan on turning it back on. We'll probably remove it at some point since we are installing a wood stove in that room.

open_circuit
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by open_circuit » Wed May 09, 2018 9:55 am

I've only had a gas fireplace for one summer so far. Last summer, I left the pilot on. This spring, I've turned it off. I suppose I'll see what effect it has this year. The pilot alone produced a noticeable amount of heat from the fireplace last summer, so it seems like a good idea to leave it off when I'm just going to try to cool the house anyway.

Regarding condensation, it is rarely over 35% RH here, and condensation is rarely a problem elsewhere in the house. I'll keep on eye on the burner this summer.

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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by friar1610 » Wed May 09, 2018 12:25 pm

I don't mean to hijack this thread but here's a related issue I just learned about in my house. We have a sealed gas fireplace with an electronic ignition that is lit by flipping a switch. I had always thought that when we had a power outage we were SOL for heat from the fireplace. This past winter one of my neighbors mentioned that he was thankful for the battery backup during a bad storm so he could at least stay warm by huddling in front of the fireplace. (These houses were all built 5 years ago by the same builder.). Looking further into I learned:
- there is a battery backup
- my batteries had corroded over 5 years
- the corrosion had damaged the "command center", the small unit which holds the batteries, so that fresh batteries didn't work

I obtained a new command center, installed it and now the fireplace lights during power outages. The supplier of the new command center recommended (and here's the tie-in to the original post) that I remove the batteries during the summer to avoid corrosion.
Friar1610

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Bylo Selhi
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by Bylo Selhi » Wed May 09, 2018 1:00 pm

friar1610 wrote:
Wed May 09, 2018 12:25 pm
This past winter one of my neighbors mentioned that he was thankful for the battery backup during a bad storm so he could at least stay warm by huddling in front of the fireplace.
Some gas fireplaces are fan-less, using convection currents to circulate warm air. We have one of those. I can confirm that there's no need to huddle around the fireplace to stay warm during a power outage.
The supplier of the new command center recommended (and here's the tie-in to the original post) that I remove the batteries during the summer to avoid corrosion.
In my experience even a fresh set of batteries installed in the autumn will fully discharge by next autumn if left in the control module year round. So pulling them out not only avoids corrosion but also allows the same set of batteries to last more than one season. (BTW thanks for reminding me. I'd forgotten to do that.)
Last edited by Bylo Selhi on Wed May 09, 2018 8:41 pm, edited 1 time in total.

davebo
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by davebo » Wed May 09, 2018 4:11 pm

I have one and I turn it off. I also get it inspected every year as well.

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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by davebo » Wed May 09, 2018 4:11 pm

I have one and I turn it off. I also get it inspected every year as well.

montanagirl
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by montanagirl » Wed May 09, 2018 9:32 pm

We turn ours off because it generates noticeable heat. I don't like running the a/c any more than we have to.

gliderpilot567
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Re: Gas Fireplace - Shut off pilot light during warm months??

Post by gliderpilot567 » Wed May 09, 2018 10:26 pm

So maybe I am missing something, but I think I learned some of the following in chemistry and physics.

The combustion products of burning natural gas include CO2 and.... water vapor. So while your pilot is lit, you are continuously adding water to your system.

Hot air can hold more evaporated moisture than cold air (which is why condensation happens as saturated air cools). So while you are adding water to your system, you are also heating the air, so the net effect there is probably a wash. BUT...

Rusting is oxidation, which is almost the same chemical reaction as burning (fire). The main difference is that rusting requires moisture, or some kind of electrolyte. A good electrolyte is carbonic acid, which is water with CO2 dissolved in it. Both of which your air in your fireplace system is saturated with because you've been burning the pilot light.

Or whenever you burn a real, big fire in your fireplace, you add water and CO2 in massive quantities. You also increase the temperature a lot. The temperature keeps all the water evaporated in the air, but after you turn it off, eventually the fireplace cools down to "pilot light only" temps. If your fireplace doesn't dissipate the water and CO2 quickly enough, they will condense inside despite the pilot being lit and start the rusting process.

My conclusion, based entirely on the above analysis and no empirical evidence whatsoever, is that I think frequent "normal use" of your fireplace will contribute more to rusting, than turning off the pilot light will.

Of course, if rain or environmental humidity enter the fireplace/furnace system, that will aggravate the effect.

Disclaimer: I do not have a fireplace or a furnace with a pilot light. I live in an extremely arid climate, with monsoonal rainfall but otherwise bone dry. The above is my interpretation of the chemistry.

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