Ask Me Help Desk - Gravity Furnace pilot: What are the extra tubes (aluminum) going to and from the pilo

On my old style gravity furnace there are a couple of seemingly aluminum tubing tubes going up to the pilot light area. They seem to have become detached from where ever they were attached to. The pilot flutters a lot and I am wondering if these tubes could have anything to do with the fluttering.

The tubes are from the old style gas pressure regulators and valves. If the diaghram ruptures they wanted to make sure the spilled gas went into the combustion chamber. Very old stuff.

Thanks hvac1000. I did some further looking into my furnace and found that there are two other aluminum lines that follow the pilot line into the combustion chamber. One comes out of the gas regulator for the main burner and the other branches off what seems to be some kind of 'T' fitting with a button on it that when pushed, releases gas from somewhere on that fitting. What got me poking and probing around the furnace in the first place was that ever since the gas company changed my meter from one indoor that was maybe several decades old to an out door model, that I assume is more modern, mt furnaces pilot has been seriously "fluttering", like a wind is blowing through it. It sounds like it is as risk of going out, ans sometimes it does. My question is do you have any idea what this fluttering could be and how to get rid of it? I figure it is air related because when I open the furnace door, it stops and the only way that I can get it to stop is to prop the furnace door open a little. I tried dialing down the pilot gas feed, but that only made it go out faster, or there was not enough heat to trip the thermocouple. And on a possible related subject, when the main burner fires, where/how does it get the oxygen to sustain itself. I can't find any vents around the furnace and the opening where the valve and related accessories are and that area has a covering to boot, which pretty much seals the combustion chamber. P.S. I did not have this problem before they changed the meter. Thanks in advance for any help or guidance.

Quote:

Originally Posted by RaymondT

Thanks hvac1000. I did some further looking into my furnace and found that there are two other aluminum lines that follow the pilot line into the combustion chamber. One comes out of the gas regulator for the main burner and the other branches off of what seems to be some kind of 'T' fitting with a button on it that when pushed, releases gas from somewhere on that fitting. What got me poking and probing around the furnace in the first place was that ever since the gas company changed my meter from one indoor that was maybe several decades old to an out door model, that I assume is more modern, mt furnaces pilot has been seriously "fluttering", like a wind is blowing through it. It sounds like it is as risk of going out, ans sometimes it does. My question is do you have any idea what this fluttering could be and how to get rid of it? I figure it is air related because when I open the furnace door, it stops and the only way that I can get it to stop is to prop the furnace door open a little. I tried dialing down the pilot gas feed, but that only made it go out faster, or there was not enough heat to trip the thermocouple. And on a possible related subject, when the main burner fires, where/how does it get the oxygen to sustain itself. I can't find any vents around the furnace and the opening where the valve and related accessories are and that area has a covering to boot, which pretty much seals the combustion chamber. P.S. I did not have this problem before they changed the meter. Thanks in advance for any help or guidance.

I would bet you have a gas pressure problem. Contact the gas company and explain the situation exactly as posted here. I believe they will come out and at least check the gas pressure as it exits the meter on your side of the pipe. The old gas meter might have been dialed down. Your pressure regulators on your burner still could be a problem and they will also need to be checked and also adjusted. This should be done by someone who has the proper tools and knows exactly what they are doing since there is a pilot adjustment and also a burner adjustment. The main burner adjustment should be set to the listing of the furnace OR if not listed on a old unit the gas meter will need to be clocked to set the BTU imput for the burner to make it safe.

Thanks again hvac1000. I'll call the gas company and try to explain this to them as you advised. The adjuster for the pilot is basically just the shut off valve where the pilot tubing branches of the line feeding the main burner. I turn that down for less flame and the fluttering stops, but it may either go out or not get hot enough to heat the thermocouple. An adjustment may where the 'T' branches off the pilot, when pushed spews pilot gas, thus the fluttering stops - but you have gas leaking at the 'T'.

Also, I am still trying to figure out how the furnaces combustion chamber is getting vented. It has to pull the oxygen from somewhere, bur where?

Thanks again!

Usually the old units pulled the combustion air from around the burner opening. Post pictures.

Thanks hvac1000, here are the photos. I again dialed down the pilot just till it stop fluttering. I'll see what happens. Thanks again!

I am glad I am not paying the gas bills on the bad boy.

Ah, it runs about 200.00 per month, on the coldest months. I have often thought of replacing it, but on more than one occasion, when I would tell the estimator what I paid each month, their eyes would glaze over when I told them what it was. It's like they wanted to ask me what was I getting a new furnace for. The prices that they would quote me as to what my bill might be like and they would indicate that $300.00 was what the least I could expect. The heat exchanger is 70 years old (1935) and the guy told me no heat exchanger will last nearly that long. It's old and cricketty, but it has only 3 components and one moving part. The furnaces nowadays are good when they are running right, but when they go out, wow! You'd better pull out that engineering degree, because they are a little more complicated. Thanks!

Quote:

Originally Posted by RaymondT

Ah, it runs about 200.00 per month, on the coldest months. I have often thought of replacing it, but on more than one occasion, when I would tell the estimator what I paid each month, their eyes would glaze over when I told them what it was. It's like they wanted to ask me what was i getting a new furnace for. The prices that they would quote me as to what my bill might be like and they would indicate that $300.00 was what the least I could expect. The heat exchanger is 70 years old (1935) and the guy told me no heat exchanger will last nearly that long. It's old and cricketty, but it has only 3 components and one moving part. The furnaces nowadays are good when they are running right, but when they go out, wow! You'd better pull out that engineering degree, because they are a little more complicated. Thanks!

200.00 a month is not bad but you have to consider the size of the home and the number of degree days etc. Your furnace installed here in my home would cost about $ 347.00 for last months degree day usage by a legit program calculation. My actual gas usage for heat only was 187.94. While I used a program to get these numbers a lot of guess work was done on the feed numbers. If you are happy with your bill keep the old beast and you are correct there sure is not much to break since it has no real moving parts or high tech boards/exchangers/motors and sensors to fail. A long time ago I remember as a very young man replacing sheer keys in old coal stokers for that style furnace you have. I also remember converting then to natural gas and how the customers complained about the gas heat not feeling as hot as the coal.

I have said that if I run across a real good deal, I would replace it, but other than that it's a keeper. Another thing that I like about it is that it will burn anything. With energy prices as dicey as they are, no telling what I may have to convert it too. The pilot thing is new though, and it gets on my nerves. After dialing it down last night it did go out, so now I have the door on the furnace pried open about 1/2 inch and it seems to be holding. I am thinking and I dread, that I will have to pull the burner/pilot assembly out to rejigger something, what I am not sure, but if calling the gas company doesn't work, I will have to put that on my agenda. Thanks again!