Take the 2-minute tour ×
Home Improvement Stack Exchange is a question and answer site for contractors and serious DIYers. It's 100% free, no registration required.

I have the pictured "knob" beside my gas fireplace. Can anybody tell me what its purpose is? I also have an on/off switch beside the fireplace. I'm guessing this is for the gas. Is there any harm in turning the switch off while the fireplace is on to test my theory?

enter image description here

share|improve this question
    
I haven't seen knobs for the flue like this (mine always required pushing a lever above the flame) but the symbols make me think Ryan is right. Other possibilities are a fresh air intake control and a gas shutoff valve. –  BMitch Aug 5 '12 at 23:03
    
If your fireplace is running, carefully check the knob to see if it is hot before you grab it. But I don't think there will be any harm in trying it. –  Steven Aug 6 '12 at 3:05

3 Answers 3

Having built and been specing equipment for all kinds of fireplaces, I would have to say that this key is used to turn a quarter-turn gas valve. If you like to reference it, you can find the same key, with the valve set up, manufactered by Arrowhead Brass.

share|improve this answer
1  
+1 that looks like the gas supply valve, not a flue control knob. –  Matthew Jan 23 '13 at 22:32
    
Certainly looks like one of these, although the markings are slightly different. arrowheadbrass.com/op_champarrow/orderportal/… –  user7116 Jan 23 '13 at 23:01

That would be the flue control. The flue is the metal duct work, ceramic piping or brick chimney stack that runs from a firebox to the top of a chimney to the outdoors. The flue directs exhaust gases and debris from a fireplace upward to vent outdoors into the atmosphere. The flue is effective because it makes use of the stack effect that happens when there's a significant temperature differential between the indoor and outdoor ends of the flue. This has the effect of drawing the exhaust gases and ash, which are lighter weight than the cold outdoor air, up through the flue and venting them outside. Some heat is lost as well in this process, and modifications can sometimes be made in or above the firebox to minimise this ancillary heat loss.

The flue has a secondary purpose of allowing fresh air to enter it, which aids in feeding or oxygenating a fire. At the fireplace end that knob allows exhaust gases to escape, and fresh air to enter, when the fireplace is in operation. The lever can be closed to prevent cold air from entering a home when the fireplace is not in use.

share|improve this answer

Before I use the fireplace I would do one of two things. Get the model# and go to hearthmaster website and down load the owners manual or contact a heating pro to explain to you how it works. The somewhat generic info on Hearthmasters website shows the knob to be the gas shutoff. If you turn it off the pilot (if it has one) will be extinguished. That means if you turn it back on and donot or cannot relight the pilot you will have a gas leak. The wall switch could be for a fan unit or an ignitor if the unit is pilotless. What all this means is that you need more information before turning or switching any thing. This is a case where knowledge is heat and no knowledge is a potential explosion.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.