Carlin 301gas in Weil Mclain 480

jfplumr

I just replaced 2 Carlin 201CRD burners in Weil Mclain 480's with Carlin 301GAS. The boilers were thoroughly cleaned and new refractories installed at burner replacement. All the numbers are within Carlin specs but I have a pronounced shudder upon ignition. It goes away after a few seconds and both units are fine for the entire cycle. I talked with Carlin tech support and couldn't come up with an answer. Any ideas? Thanks

Steamhead

Do you have

proper over-fire pressure? Don't have it handy but I believe you need +.01 at the breech....

jfplumr

overfire pressure

Carlin calls for .34" positive and I have met that requirement.

JStar

Shudder

Too much primary air? Poor chimney draft? What were your exact combustion numbers?

Steamhead

Do these burners

have pre-purge controls? If so, are they working? It sounds like there might not be quite enough oxygen available at light-off.



The draft must remain steady between the breech damper and the chimney. If there is no barometric draft regulator, you may find that the running draft (after the chimney has warmed up) is much higher than the draft at light-off. This means that if you set the breech damper for proper over-fire pressure when the chimney is warm, you'll have too much over-fire pressure when it is cold. The solution is to install a barometric.



If the chimney was designed for coal firing, as all pre-WW2 ones were, you would do well to use a barometric one size larger than the chimney connector. Such chimneys can pull pets and small children up to the roof, and can overwhelm a barometric sized to the chimney connector.



For gas, Code requires a double-swing barometric, with a blocked-flue switch properly mounted on it.



If pre-purge and draft regulation are OK, try decreasing the over-fire pressure by opening the breech damper a notch or two.

jfplumr

problem solved

Thanks for your responses. After talking with John at Carlin tech support it was determined that a gas valve vent orifice had not been installed. Once I installed these orifices everything was fine. Thanks again to Carlin tech support.