gas valve housing cuts off air flow

jeffrey

This is a gas conversion on a Very old boiler that happened decades ago. Started out as coal. I've noticed that the flame, when the boiler is on is blue at bottom, but mostly orange. It has been like this ever since I can remember. In the past a professional heating company had done yearly maintenance calls.

Today I vacuumed out the soot from inside. This didn't change the orange flame. Just for kicks I took the cover off the valve assembly (Roberts-Gordon Appliance Corp. burner no. 302-21X, min/max input btu/hr: 45k, 300k) . There was an air adjustment, large nut to back off, with large flange to back off, allowing more air into burner. this seemed to turn the flame from orange to blue (mostly, a few orange tips). Great!

Then I noticed, when putting the cover back on the assembly, the flame went back to orange. Seems that with the cover on the assembly, there is no way for air to get in. Apparently it has been operating this way for decades.

Shall i just leave the cover off? Is there some reason that it is designed to operate with very incomplete combustion- blue flame at bottom but mostly orange? Will it be creating too much heat now and damaging the boiler?

comments?

Tim McElwain

A couple of pictures would help me to help you!

jeffrey

I agree. i've done it twice. i'll try a third time.

jeffrey

btw: inside of firebox is some type of iron. a magnet sticks to it. there are brick like discs on bottom that the flame comes out around. I notice that with the valve housing cover off, the flame gets hot enough to turn some edges of discs red hot. this doesn't seem to happen with the cover on the valve housing cover in place.

retiredguy

Can you post a couple pictures of the burners both off and being fired. That is an old gas conversion unit. Some of them would burn with slightly orange/yellow tips. It was just how they burned. Wow, that thing is very old. That pilot safety looks like a bi-metal type. I never liked those due to safety issues.

Tim McElwain

It is not unusual for the flame to be slightly orange especially when things are being moved around. That conversion must be operated with the cover in place. Yellow flames are a problem as they will soot up if the impinge on cooler surfaces.

jeffrey

sorry about the sizes. resizing doesn't seem to be an option. can't drag corners to make them smaller.



pic of boiler with firebox door open



pic of bottom of inside of firebox. flames come out around the round discs on bottom. with valve assembly cover off , and flames more blue, the bottom edges of discs will get red hot. as you can see, the discs broken into several pieces long ago.



one pic of flames with cover on. cover on seems like it cuts off air flow to gas tube. with the cover on, i don't see any easy way for air to get to gas tube, short of leakage around cover.



another pic of flames with cover on.



and finally, pic of flames with cover off. this is when bottom edge of round disks will get red hot.

interested to hear your comments.

retiredguy

You need someone to pour you a new refractory disk to replace that broken one. Also, the hotter that refractory top piece gets the cleaner the flame will burn. The 2 middle pictures show a dirty flame caused by either a poor gas/air mix or not enough primary/secondary air. You may need to disassemble that burner to see if any parts have become plugged or dislodged not allowing proper air flow to either the primary or secondary air. The gas orfice may also be worn to an oversize which will reduce the primary air to the burner. That probably can not be fixed unless parts for that burner are still being made.

jeffrey

the two middle pictures show the flame with the cover on the valve assembly.
the bottom pic is when the cover is off. as i mentioned, I don't see how it would get air with the cover on. the boiler is closed to floor lever, and other than leakage around cover, there is no air inlet.

this is the obvious cause of lack of air, as far as I can tell.

i am not about to start disassembling the burner, since it could be the end of the boiler, and I don't really know how to judge what I am looking at. eg, i don't know what primary vs secondary air means.

the question at this point is whether to just let it be, with the cover on, and live with the partly orange flame. or will leaving the cover off give a blue flame, but damage the boiler in some other way?

mattmia2

You should find someone that is good at setting up combustion to take a look at it, probably someone that works on commercial burners and oil burners. There is a good chance either it was never set up right or someone servicing it sealed up a damper that had been set to provide draft by whoever converted.

Probably much beyond that and it makes more sense to just put in a new boiler. You could replace that with a gas power burner but you'd spend a lot to patch together something that could last another 30 years or could leak tomorrow.

EBEBRATT-Ed

The bottom picture looks like a reasonable flame but you don't know unless it's tested.

Best bet would be to install a new burner. The hard part would be finding someone who could actually do it right

jeffrey

thanks. I suspect that calling a boiler co. in to take a look will likely present a collection different possible options, but most likely will be the suggestion to install new, since that is what they are most familiar with doing. Most service people have likely not seen a unit half the age of this one. quarter the age?

perhaps I will leave the cover off, and close the air inlet down, and split the difference between the current state and burning a mostly blue flame. I don't want to destroy something by it burning too hot, if that is even possible.