Moisture in Manifold

[ascj]

I went to an account today, that has 4 MUA's. One was down, found a linkage knuckle broken, replaced. I just happen to take a look at the burner, and saw moisture in some of the orifices. Hmm, so I take a quick look at the other units and the same thing.

What would case moisture in the manifold? I wanted to open the drip leg feeding the gas train, but the are feed up though the roof and the drip leg was 40' in the air.

I wouldn't think there would be moisture at the orifices, being that the manifold is under a negative pressure.

Any ideas?

[JYoung Guy]

I've had whole 1/2" pilot lines on a MUA blocked with ice, only thing that I thought of and was told that its condensation formed on initial firing and or right after shut downs.

[ascj]

I've had whole 1/2" pilot lines on a MUA blocked with ice, only thing that I thought of and was told that its condensation formed on initial firing and or right after shut downs.

I just can't see how that can happen, with a pilot line.

My thinking about the manifold, was since it's in the air stream and full of air, I could get some sweating with warmer weather. But my personally argument, is the change in temp would be slow. There shouldn't be a big change in temperature.