Blichmann Burner; NG conversion; low flame

[ThatTWirp]

I have a blichmann burner with a natural gas conversion kit. I linked the burner to the natural gas coming in from the wall and I made sure to use the smaller 1/8" aperture hex nipple into the burner itself that came with the conversion kit (the default hex connection for propane is larger).

However, the burner still burns incredibly low. The natural gas coming from the wall is 7" water column, which should be suitable for the burner. After trying several settings, nothing works. If I turn it on full blast, the burners all go out, but it never shows a good burn. The highest burner tip I can get is maybe about 1/4", if I blow on them they go out.

I split the gas line with a T-connector to bring the gas to where I need it. Might that because the pressure to drop further? One line goes to the dryer, which is always on because wife, the split line goes to the burner but I added a ball valve I can turn on and off by the wall (as well as another ball valve near the burner in addition to the more finely adjustable valve with the converter kit).

What I don't quite understand is why the NG conversion kit's valve would reduce to a 3/8" male flare entering the valve, then increase back to 1/2" (I have 1/2" coming all the way to the valve) only to drop to what looks like 1/4" then the 1/8" pinhole. The reductions I understand (to increase pressure), but why would they increase to 1/2" before dropping down again, seems a bit nuts.

Anyone else have or had this problem and know a good solution?

 

[feinbera]

I've got a similar setup (Blichmann burner w/ NG conversion kit, hooked up to preexisting gas grill line), and it works like a charm – 1.5 gal/hour boil-off when I set up my super-professional-quality windscreen (read: one side of the box my chest freezer came in, zip tied to a patio chair and positioned slightly upwind), so, you should be able to get this setup working.

Have you tried running the burner when the dryer's off? Does it help? Cooperative scheduling of brewing and laundry doesn't sound like much fun... but it does sound better than seven gallons of lukewarm wort.

Did your conversion kit come with a brass needle valve? Is it all the way open? I know this sounds like a dumb question, but I've screwed up too many should-be-idiot-proof things to take anything for granted.

 

[ThatTWirp]

I've got a similar setup (Blichmann burner w/ NG conversion kit, hooked up to preexisting gas grill line), and it works like a charm – 1.5 gal/hour boil-off when I set up my super-professional-quality windscreen (read: one side of the box my chest freezer came in, zip tied to a patio chair and positioned slightly upwind), so, you should be able to get this setup working.

Have you tried running the burner when the dryer's off? Does it help? Cooperative scheduling of brewing and laundry doesn't sound like much fun... but it does sound better than seven gallons of lukewarm wort.

Did your conversion kit come with a brass needle valve? Is it all the way open? I know this sounds like a dumb question, but I've screwed up too many should-be-idiot-proof things to take anything for granted.

After consulting a chemist friend who works on sour gas streams, he said the split would drop the pressure from 7" WC to 3 1/2" WC in both lines, so he recommended another valve on the dryer side. That means either brewing or doing laundry.

I attached this today and shut off the dryer side. It's working much better. However, still not up to snuff.

He said to go retighten everything and pick up an NG flow meter to measure the pressure at various points in the line (to see if there is minor leakage) or a gas sniffer to sniff for the leaks. That's next up, but I'm getting optimistic about it.

I have the needle valve they sent, so it really must just be an issue with minor leaks at the various connections.

 

[acidrain]

Are you sure you have the right orifice in it? The NG insert is visibly much bigger (the actual hole).
Did you adjust the air damper? Start with it barely open... it should be yellow/smoky flame. Then open it until you have blue flames that doesn't blow out.

 

[ThatTWirp]

Finally working up to par. The problem was that in splitting the gasline, you drop the pressure in both lines 50% (so I went from 7" WC to 3 1/2" WC). Putting a valve on both lines allows me to keep full pressure in the burner line when I need it and the dryer line other times.

[skip this for tl;dr if you want]
The opening was a secondary problem. I had the right one on when I first tried it with low pressure, so I switched to the smaller one hoping to increase pressure. Then I put the valves on, but it still didn't work right because the aperture was too small. Finally put the right one on that had been there in the first place and that plus the valve fixed it.

Brew day tomorrow!!