How a Gas Log Safety Pilot Works
and how to light a gas log safety pilot.
For details about gas log burners read: Gas Log Burners and Safety Pilot Controls
How does a gas log safety pilot work?
Aside from the electronic ignition systems, the basic premise for the safety pilots used on gas logs is the same as those used for decades with wall heaters,
hot water heaters, and nameless other gas appliances.
How do you light a gas log safety pilot?
You turn the control knob to the pilot position, push the knob in, light the pilot with a match, then hold the knob down for 30 seconds or so until the pilot stays lit by itself. Once the pilot light
will stay lit on its own, you can then move the knob to the "On" position. For manually operated gas logs such as the one pictured to the right, this will turn the logs on. For remote controlled
gas logs, this will put the valve in the necessary position for the remote control to actuate the burner.
What if the pilot will not stay lit?
If you cannot get the pilot to light at all, meaning you hold the button down in the pilot position and hold a match up to the pilot and nothing happens,
then either the valve is bad or something is abstructing the gas from coming into or going through the valve. If you can get the pilot to light with a match, but it will not stay
lit on its own after holding down the knob for 30 seconds, then put the knob back into the off position, wait 5 minutes and try again. If it still will not light, then something is definately wrong and
you should have a professional check it out.
This page is not meant to be a trouble-shooting guide for gas logs, but in general, if you cannot get your safety pilot to stay lit, It could be that the pilot flame needs adjustment, the
thermocouple has gone bad and needs to be replaced, the entire valve has overheated and must be replaced, or something is abstructing the gas line. In any case, it is probably time to seek the assistance
of a professional. Any plumber or heating and air conditioning service man who deals with gas appliances with a safety pilot should be able to help you.
How does a safety pilot actually work?
Although most of us have learned how to light one of these things at some time or other, few of us have any idea as to how this ingenious little safety system actually works.
So here is a brief, but hopefully useful explanation of how gas log safety pilots work so you can decide if it is something that you want or need. You may also find this information
helpful for any other device that has a similar safety pilot.
Gas Logs that have a safety pilot have a valve body that is attached directly to the burner. This valve body that has 2 separate valves inside that control the gas:
The valve to the main burner and the valve to the pilot flame.
When the pilot is lit, the flame directly hits what is called a thermocouple (or thermopile).
The thermocouple is the ingenious device that makes the whole system work. The physical properties of the thermocouple are such that it actually generates electricity when there is a great
enough difference in temparature between the tip of the thermocouple and the base.
If the pilot flame is too hot, then the entire thermocouple gets hot and there is not enough temperature difference to create a current. If the pilot
flame is too low or not coming into direct contact with the thermocouple (or simply blown out), then there is not enough heat to generate a current.
This is why the proper adjustment of the pilot flame is necessary for gas appliances that have a safety pilot.
Now, on to how the pilot system works.
The electricity from the thermocouple is used to power an electromagnet that holds the pilot valve open, thus allowing the pilot to stay lit by itself. The amount of electricity needed
must be within a certain range of millivolts in order for this to happen. If there is not enough electricity (or no electricity) being generated,
then the electromagnet no longer functions and the pilot valve shuts. When you turn the knob to the pilot position and push it in, you are in fact manually opening the valve to the
pilot flame. Once the pilot gets the thermocouple hot enough, the electromagnet engages and keeps the valve open.
This is why you need to keep the knob depressed for about 30 seconds.
After the pilot is lit and stays lit on its own after releasing the pilot know, you can then turn the knob to the "ON" position.
With manually operated safety pilots, turning the knob to the on position
will light the logs and you can adjust the flame height using the control knob.
With remote controlled systems, turning the knob to the on position simply puts the main valve in a position to be opened and closed
buy whatever means the remote control uses. In the case of a remote controlled valve, some will have a battery operated device that opens and closes the valve to the main burner, thus turning the logs
on and off. More sophisticated systems (called variable flame remotes) will have a battery operated motor attached to the flame adjustment knob that will allow you to adjust the flame height as well.
The main burner valve is designed such that if the pilot valve is closed, no gas can flow through the main valve, even if you have it in the on position.
So as long as the pilot light is on and heating the thermocouple
properly, the system is operational and gas can then be allowed to pass through the main burner valve. If the pilot light gets turned off or blown out (or in some cases gets too hot),
then all valves are closed and no gas can pass through the system.
When the main burner is turned on, either by a remote controlled unit or by manually turning a knob, gas flows through the main valve and comes out the holes in the burner.
The flame from the safety pilot is positioned just above the first several holes in the main burner, so when gas flows out of the main burner and reaches the safety pilot, it automatically ignites.
So again, if the safety pilot is not lit (or for some reason the safety pilot gets blown out), the system automatically closes both valves so that no gas will
flow through either valve until the safety pilot is re-lit.
This prevents the system from allowing gas to flow freely into your home at any time in the event that the safety pilot blows out, or someone turns on the gas to your fireplace
without lighting it.
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Answers to Recent Gas Logs Questions Posted To This Page
- Question #9527 - Posted: 2/2/2017 8:52:54 PM
Gas Logs Question Model PL-CHCRG46-30-17P
QUESTION: 1. How large in diameter will the vent hose need to be for this type of unit?...Thanks, Frank
I am assuming that you are referring to the size of the chimney. This gas log is designed to be installed in an existing wood burning fireplace that is capable of burning wood. If you do not already have a wood burning fireplace, then you cannot install this gas log without one. With that said, the minimum required vent depends on the height of the chimney. Please refer to this chart copied from the installation manual for specifics:
- Question #9526 - Posted: 12/29/2016 9:05:21 PM
Gas Logs Question
QUESTION: I have a gas burning fireplace with a broken log. It was originally a wood-burning fireplace built in the early 1960s. It has a damper which is always open when burning. The fireplace was converted professionally to gas sometime before 2000. I converted it to remote-control lighting in 2010 using a reputable firm. Sometime later, one of the logs was dropped and cracked in half. It is held together by internal wires.
I would like to replace one log rather than the entire set. Possible?
ANSWER: It is possible, but that depends on the type of gas log set you have. If you can email us a picture of your gas logs, maybe we can find what you need. Email pictures to: email@example.com
- Question #9525 - Posted: 12/29/2016 8:58:26 PM
Gas Logs Question
QUESTION: I have a classic fireplace 26" in the back, 36" in the front and 26" depth. I live in a two story house built in 1935. The furnace broke and needs to be replaced. I'm looking for something to install in my fireplace to warm up the living room. I live in California so it has to be vented. What do you recommend to keep my room the warmest it can be? log set or would an insert be better?
A vented gas log is not going to provide very much warmth for your room. Since you cannot install a ventless gas log in California, you are left with the option of installing a gas insert. I would suggest taking a look at the Real Fyre Direct Vent gas insert
- Question #9524 - Posted: 12/29/2016 8:51:36 PM
Gas Logs Question
QUESTION: i live in a 100 year old house and my fireplace was for coal and has a metal firebox. i have burned wood in it until last year, until we realized there was some leakage of smoke from the chimney upstairs. Would it be safe to use vented gas logs? Would we need to line the chimney like we would need to if we continued burning wood?
ANSWER: Burning a vented gas log produces smoke just like burning real wood, so yes, you would have to reline or repair the chimney. I would suggest considering a ventless gas log so do not have to worry about smoke.
- Question #9523 - Posted: 12/29/2016 8:45:42 PM
Gas Logs Question
QUESTION: what size and kind can I put in a woodstove "MORE HEAT" that has a door 20 BY 8.5 FIREBOX 28 BY 18 AND IS 12 INCHE DEEP and will they warm the stove enough to product heat with the fan.
Unfortunately, you cannot install gas logs in a wood stove. Wood stoves are designed to operate with much lower draft than gas logs and the venting does not meet the minimum venting diameter. Even more, air tight wood stoves are designed to be burned with the doors closed, which is a definite no no when it comes to burning gas logs since they must be burned with the doors opened. There are other reasons why gas logs will not work in a stove, but I will not belabor that here. For more details, read more about Where Gas Logs Can Be Installed
- Question #9522 - Posted: 12/29/2016 7:59:50 PM
Gas Logs Question
QUESTION: I have a 24" peterson gas log set. The gas line in the fireplace is slightly larger than the connection for flex tube that leads to the gas burner. Can I add a smaller fitting to attach to the line leading to the burner?
ANSWER: That should not be a problem unless the incoming gas pressure is higher than allowed by the installation manual, so you may want to check that.
- Question #9521 - Posted: 12/29/2016 7:53:16 PM
Gas Logs Question
QUESTION: I occasionally turn our ceiling fan on low with the blades drawing the air upward while using our ventless gas logs. Our installation manual says a ceiling fan should not be used when the ventless logs are on. The flame of the gass logs appears to be unaffected. Is there a problem in having a ceiling fan on at the same time as the ventless gas logs? Thank you.
ANSWER: Running a ceiling fan to destratify the air in your room makes sense from a heating efficiency/conservation standpoint, so I understand why you are asking your question. The responsible answer is that the owners manual says not to run your fan when you are operating your ventless gas log, so we cannot tell you that it is OK to do so. With that said, drafts can certainly cause ventless gas logs to NOT burn correctly and start producing toxic odorless Carbon Monoxide. It is safer for the manufacturer to tell you not to run your fan at all in order to avoid a potentially hazardous outcome rather than suggest that you can run it on a low speed in reverse with no ill effect. They cannot test the actual impact of doing so in your particular room. Their ultimate concern is to prevent any draft from affecting the flame. Whether you decide to follow the instructions is ultimately your decision...I will leave it at that.
- Question #9520 - Posted: 12/29/2016 7:31:40 PM
Gas Logs Question
QUESTION: I do not really need the heat, and I have a fireplace already,but, the damper is either all the way open or completely closed. can I get that fixed so i can have it open part of the way so all the hot air does not go up the chimney thereby kind of making it silly to have one
ANSWER: Technically, a vented gas log is supposed to be burned with the damper completely open. Plus, you cannot ever completely close the damper just in case there is a gas leak, so there is a clamp that is included with the burner system that gets attached to the damper to prevent it from ever closing completely. So if you do not really need the heat, then the way your damper operates is sufficient for a vented gas log. Whether you close the damper slightly to preserve some of the heat will not make much difference, you will get most of the heat from a vented gas log radiated into the room from the ceramic in the logs themselves. If you are really concerned about getting heat (which you say you are not), then you should consider buying a ventless gas log.
- Question #9519 - Posted: 12/29/2016 7:02:36 PM
Gas Logs Question
QUESTION: Question - Are there burners or logs that are better for use with propane to achieve the best flame presentation? Currently my propane flame in my FP is not as robust as I would like. Just curious if there are options that are better for propane specifically.
ANSWER: Whether you are burning natural gas or liquid propane, each type of burner is configured for optimal performance for the gas you are using. So you would need to make sure you order a burner system for Propane gas, otherwise it will not perform properly. With that said, if you want the most robust flame, we would recommend either the G4 or G45 burners since they operate at the highest BTU (the most flame). However, neither of these may not be the best choice for your particular fireplace depending on the type of fireplace you have and the dimensions. Please send us some pictures of your current setup so we can see what you have and make further recommendations. Email pictures to: firstname.lastname@example.org.
- Question #9518 - Posted: 12/29/2016 6:53:51 PM
Gas Logs Question
QUESTION: Where do I find a remote control for my gas logs? And how much?
ANSWER: Gas log remote controls are not universal in design. They are made as a transmitter and receiver combination, the receiver usually a built-in component of the gas log valve and burner system. So if you have an existing gas log with a remote and you are looking to replace a remote that is no longer working, you are going to need to contact the manufacturer of the gas log system you own and see if they can supply you with a replacement remote. If you are wanting to add a remote control to an existing gas log, that is a different story. In most cases, you will need to replace the entire burner system with one that is remote capable. Replacing the burner system may also require you to replace the logs since not all logs are compatible with all burners. If you email us some pictures of your fireplace we may be able to offer more direct advice. Send your pictures to: email@example.com...or just give us a call at: 1-800-201-1193.