Adjusting furnace gas regulator?

Daox · 09-22-12, 09:29 AM

I just fired up the furnace for the first time this year. I did the normal simple maintenance of putting in a new filter, and vacuuming up the inside bits. I also observed it as it started up for the first time this year. The fan motor sounds good, but the flame has a bit too much yellow/orange in it. I know in general when burning natural gas yellow/orange means inefficient combustion. So, I went an grabbed my camera and took a short video.

I'm really hoping that someone can help me adjust the gas regulator as that is what I assume needs to be adjusted. When I first purchased the house I did have a buddy who does HVAC work come and check it out and he did adjust the gas regulator a tiny bit at that point. I believe he used a manometer to measure the pressure. Is this the way things NEED to be done?

natural gas furnace running - YouTube

Daox · 09-23-12, 09:04 AM

I did a bit more searching on this and it doesn't seem I have too much to worry about. Orange flame is usually dust getting sucked into the flame. I didn't vacuum it out THAT good, so I'm not surprised there is dust being sucked in there. However, yellow flame is what needs to be avoided and that is evidence of an inefficient burn. I don't recall and its hard to see from the video, but I think most of the flame I saw was more orange than yellow. I'll check on it next time I fire up the furnace.

Piwoslaw · 10-25-12, 02:51 PM

My boiler broke down last week and I asked the serviceman about adjusting the air/fuel mixture. He said that normal boilers don't need adjusting, only condensing models do.

I also asked about the yellow/orange color of the flame coming out of the burner and whether it's from debris. He said yes and said that the burner should be removed and blown out with compressed air. He claimed that it's as easy as removing 4 screws and that I could do it myself.

My boiler turn out to be beyond repair, but at least I got some info to share here.

Daox · 10-25-12, 04:18 PM

Interesting, yeah my furnace is a condensing furnace. When my buddy tweaked it the first year I moved in, it was off by a very small amount.

Mikesolar · 10-25-12, 06:02 PM

No adjustment necessary on your furnace. Some of the yellow is from residual dust in the combustion air and NG usually has a yellow tip.

Natural gas, by Ontario code, can typically be derated 10% but that is about all you can do to a naturally vented furnace or boiler. Most Condensing/modulating boilers do need to be set up. Some do not, such as Viessmann Vitodens 200 but all boilers and furnaces should be checked seasonally. I don't think your furnace is modulating though.

MN Renovator · 10-26-12, 06:18 AM

Mine has quite a bit of yellow in it and mine is running a little over rate because it was the only way to get a combustion analyzer to show efficient numbers for my furnace. I really wouldn't bother touching it or even having someone touch it unless they have a good combustion analyzer and a manometer.

One thing I noticed is you've got some puffy flame coming from your far left burner, does this look the same before and after the blower kicks on? It looks a little more wild than I've seen coming from a condensing furnace. ..then again usually I'm looking at condensing furnaces that are 2-pipe installs. Something I'm looking to upgrade to as soon as mine fails because I'm sitting on a builder's grade natural draft 76% efficient furnace coming up on 29 years old.

For what it's worth my flame looks a little rough until it's been running a few minutes and usually also a bit more yellow at the beginning of the season until I run it for a good 30 mins straight. You could try letting your house cool down 5 degrees or so and giving it a 30 minute run and see if it clears up a little. Might or might not but yours doesn't look bad to me so you might not see a difference. Natural gas isn't perfect in quality as it isn't pure methane and has its imperfections.

Mikesolar · 10-26-12, 06:34 AM

That's all normal. Any combustion device needs to get up to proper operating temp and stabilize. Any dust will be pushed up with the gas/air pressure and burn off after the summer.

Fornax · 10-30-12, 03:47 AM

Quote:

Originally Posted by Daox

However, yellow flame is what needs to be avoided and that is evidence of an inefficient burn.

The yellow flames to be avoided here are how a candle burns yellow.
Such a flame is caused by inefficient burn where in part of the flame there is lack of oxygen. The fuel there partly burns to CO2 but also tiny particles of solid carbon are formed which glow up yellow and orang by being heated in the flame.

As other people stated above the orange 'flares' visible in your video are just dustparticles that get sucked into the flames. (And those do not burn up entirely and/or they colour the flame because of the elements in them (Like sodium in kitchensalt colours a flame orange))

09-23-12, 09:04 AM	#2
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	I did a bit more searching on this and it doesn't seem I have too much to worry about. Orange flame is usually dust getting sucked into the flame. I didn't vacuum it out THAT good, so I'm not surprised there is dust being sucked in there. However, yellow flame is what needs to be avoided and that is evidence of an inefficient burn. I don't recall and its hard to see from the video, but I think most of the flame I saw was more orange than yellow. I'll check on it next time I fire up the furnace. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-25-12, 02:51 PM	#3
Piwoslaw Super Moderator Join Date: May 2009 Location: Warsaw, Poland Posts: 961 Thanks: 188 Thanked 110 Times in 86 Posts	My boiler broke down last week and I asked the serviceman about adjusting the air/fuel mixture. He said that normal boilers don't need adjusting, only condensing models do. I also asked about the yellow/orange color of the flame coming out of the burner and whether it's from debris. He said yes and said that the burner should be removed and blown out with compressed air. He claimed that it's as easy as removing 4 screws and that I could do it myself. My boiler turn out to be beyond repair, but at least I got some info to share here. __________________ Ecorenovation - the bottomless piggy bank that tries to tame the energy hog.

10-25-12, 04:18 PM	#4
Daox Administrator Join Date: Aug 2008 Location: Germantown, WI Posts: 5,525 Thanks: 1,162 Thanked 374 Times in 305 Posts	Interesting, yeah my furnace is a condensing furnace. When my buddy tweaked it the first year I moved in, it was off by a very small amount. __________________ Current project - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. & To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

10-25-12, 06:02 PM	#5
Mikesolar Master EcoRenovator Join Date: Aug 2012 Location: Toronto Posts: 958 Thanks: 40 Thanked 158 Times in 150 Posts	No adjustment necessary on your furnace. Some of the yellow is from residual dust in the combustion air and NG usually has a yellow tip. Natural gas, by Ontario code, can typically be derated 10% but that is about all you can do to a naturally vented furnace or boiler. Most Condensing/modulating boilers do need to be set up. Some do not, such as Viessmann Vitodens 200 but all boilers and furnaces should be checked seasonally. I don't think your furnace is modulating though. Last edited by Mikesolar; 10-25-12 at 06:05 PM..

10-26-12, 06:18 AM	#6
MN Renovator Less usage=Cheaper bills Join Date: Nov 2010 Location: Minneapolis, MN Posts: 939 Thanks: 41 Thanked 116 Times in 90 Posts	Mine has quite a bit of yellow in it and mine is running a little over rate because it was the only way to get a combustion analyzer to show efficient numbers for my furnace. I really wouldn't bother touching it or even having someone touch it unless they have a good combustion analyzer and a manometer. One thing I noticed is you've got some puffy flame coming from your far left burner, does this look the same before and after the blower kicks on? It looks a little more wild than I've seen coming from a condensing furnace. ..then again usually I'm looking at condensing furnaces that are 2-pipe installs. Something I'm looking to upgrade to as soon as mine fails because I'm sitting on a builder's grade natural draft 76% efficient furnace coming up on 29 years old. For what it's worth my flame looks a little rough until it's been running a few minutes and usually also a bit more yellow at the beginning of the season until I run it for a good 30 mins straight. You could try letting your house cool down 5 degrees or so and giving it a 30 minute run and see if it clears up a little. Might or might not but yours doesn't look bad to me so you might not see a difference. Natural gas isn't perfect in quality as it isn't pure methane and has its imperfections.

10-26-12, 06:34 AM	#7
Mikesolar Master EcoRenovator Join Date: Aug 2012 Location: Toronto Posts: 958 Thanks: 40 Thanked 158 Times in 150 Posts	That's all normal. Any combustion device needs to get up to proper operating temp and stabilize. Any dust will be pushed up with the gas/air pressure and burn off after the summer.