Beckett air shuttle stuck

seized123

This really might be a dumb question but:
the air shuttle adjustment disc is stuck on my Beckett AFG. I can’t move the pointer beyond the 6-8 range in either direction. I loosened the locknut on top and don’t see any others. Thought it would be better to check with you folks about where I should look before I start tinkering and break something.

seized123

And while I’m at it let me send a kind of semi-related question besides the stuck air shuttle.

I’m using my new old Bacharach 10-5022 wet kit I just got from eBay. Weil-McLean WGO-3 with the Beckett AFG. First numbers are draft 0.01 over fire and 0.04 at breech, which is good, zero smoke but I wanted to get a trace and then open it to just zero like they say to, which is why I wanted to move the air shuttle. (It was at 8 and I lowered it to 6 and I still got zero.)

Also I got 13.5 CO2. I saw somewhere that normal is 9-12.5. So my question is, how concerned should I be about the 13.5?

HVACNUT

If it's a recent series and has the Clean Cut pump, then there might be another 5/16 hex screw in the 6 o'clock position on the air shutter.
Get the CO2 down to between 10 and 12 percent, as long as draft and smoke are good.
Does the burner have the F head or L head? It was offered both ways.

seized123

It’s the F-head. I forgot to say flue gas temp was 480 degrees when steady.

It’s not the clean cut pump, it’s a Suntec A2VA-7116 I think (from memory, not at home now).

seized123

(And I have no idea why I wrote air shuttle instead of shutter.)

STEVEusaPA

For your combustion set up, it’s hard to say without more combustion numbers. Which are the numbers you don’t get with a wet kit.
Specifically, CO and Excess Air. So without the full picture, 13.5 can be great, or it could be real bad.
I’ve never had a shutter stick in over 30 years. Maybe it’s internally bent, another screw like @HVACNUT stated, or something is in there hanging it up.

seized123

@HVACNUT, yes! There is a nut at 6 o'clock, I didn't see it because it's all gunked over and mostly because it's almost hidden by a bottom plug of the Suntec pump that made it a little tricky to loosen but I did it and was in business. (Told you I was asking a stupid question, but thanks, your comment made me go back and find it.)

Also, now that I could move the shutter I got it down to 12%, good draft, zero smoke after first decreasing air, getting smoke, and decreasing until no smoke (actually I decreased air and then measured C02 first and then smoke, then increased air until I got 12% CO2, then measured smoke which sure enough was zero).

@STEVEusaPA, a day or two ago I didn't know any of this stuff, but now I'm guessing that what you mean by 13.5 can be great or bad is that with the wet kit I don't know which side of the stoichiometric line I'm on, even though I'm getting no smoke (as I've heard that somehow you can be on the left, or bad, side of the line and not get smoke, though I don't know how that happens, so no smoke does not necessarily mean you're on the right side).

Now from what I understand, the electronic testers measure 02 directly (and calculate CO2 from that), and, since theoretically according to the combustion curves there is no 02 on the left side of the line, if you're getting a significant 02 percentage you know you're probably on the right side. But with the CO2 tester in the wet kit, an increased or decreased percentage of CO2 could be due to a decreased or increased percentage of 02, but it also might be due to CO, and in that case you're probably on the left side of the line and might never know it. Am I seeing the situation right?

Here's my next issue related to all that: What I did was, as is apparently recommended by some, I closed the shutter some to get less air and took a smoke AND a CO2 reading. CO2 was then higher than at the original air shutter setting, and now I got smoke where at first there was none. Then I opened the shutter up some as they say to do and measured CO2 until got 12%, then measured smoke and got zero.

Now since the CO2 percentage went down with more air, I figure this tells me I'm most likely on the right side of the combustion curve, because the way the curve goes on the left side, if you increase air, CO2 goes up not down.

I hope I'm thinking about this right, all comments welcome. (I'm going to start another thread though probably with this question and others about the Combustion Curve, because this thread is supposedly just about a hex nut I overlooked.) For one thing, I've read some stuff on this site about how nothing is written in stone (never is), and sometimes there can be O2 on the left side of the curve, and CO on the right! Yeesh!

seized123

Oops, in the second paragraph I meant to say: ... zero smoke after first decreasing air, getting smoke, and increasing air until no smoke

MikeAmann

I followed what you said and I believe you have it right.
Actually what you wrote helped me to understand this a little better.

seized123

Cool. I’m now trying to wrap my brain around whether the wet kit can have a blind spot with respect to CO, even if you’re getting no smoke and less CO2 with more air. (In other words, should I spring for a CO tester to get a complete picture.)

MikeAmann

Personally, I wouldn't. Would you be able to run all these tests AT THE SAME TIME?
If not, then you will have slightly different conditions and the numbers you get might not give you the clear picture you are looking for.
Don't forget that you have to add a little extra air to compensate for changes that occur during operation, mainly the draft. You can't control the outside temperature or the wind. This gives you a safety margin.
Lower your CO2 by 1/2 percent.

seized123

Interesting, and those CO testers do seem expensive. 

When I checked the other day I adjusted the air to get about 12.5.

MikeAmann

Generally, you want to get to just a trace of smoke, and IF your numbers fall within specs, then you lower the CO2 by 1/2 percent and lock the adjustment there. You sacrifice 1% efficiency in doing this, but your burner will remain clean through the heating season. All it will cost you is about $5.00 for the entire heating season.

Only under controlled lab conditions could you lock the adjustment at zero smoke, right at the point of showing a trace. But that is not the world that the burner will be operating in. So the outdoor condition changes which causes the burner to have smoke, maybe a little, maybe a lot. That smoke will soot up the heat exchanger which now kills your efficiency. And it's going to cost a lot more than $5.00 to clean the burner and combustion chamber and heat exchanger.