New oil burner bangs on start up

[Ford350]

Just had a new oil fired boiler with a new burner installed at my mother's house. It's a Peerless WBV-03 with a Carlin EZ1-2-3 burner (not sure which exact Carlin model is on it).

Whenever it starts the burner motor runs at first with no firing, then after a delay of several seconds it gives out a loud THUMP! and starts firing. The thump is noticeable throughout the house and bangs the barometric damper shut. There is also a slight odor of exhaust at the damper right after it bangs. I'm concerned that one day it will blow the smoke pipe out of the chimney, it's really a loud event.

I'm told this thing is running a pre-purge cycle, and that's why it doesn't fire immediately, but the thumping behavior sure seems like delayed ignition to me. Is this normal behavior? Do pre-purge burners have an explosive type of startup? Is there a way I can tell if this unit is even capable of a pre-purge cycle?

This just doesn't seem right to me. Any opinions on this would be appreciated.

Thanks.

[Advanced Response]

get the contractor back out.. The unit was not properly set up!!!

J

[beenthere]

Could be delaying after the prepurge.

Call the company. And ask them what the combustion reading were when they commissioned the boiler.

[trout lake]

You definately need to call the contractor back as the boys are saying. You shouild do this right away. There can be various reasons why it is doing that. The blower running on pre-purge on that unit is normal. The banging sounds like delayed ignition as you say. They will need to test the pressures and ensure the gap on the electrodes is set correctly. Sometimes on new installs they can be put out of line from handling and the like

[CynicX]

I wouldnt say its "normal" but I'd say its common with a small boiler with a burner with a pre/post purge.

The pump will build up pressure and after 15 seconds open a valve and all the oil is ignited. This makes for cleaner burner operation. Sometimes it will come on with a bang, not so much a bang but will throw the barametric damper closed then open.

There are some adjustments that can help the situation. I'd have the contractor come back out and see if they can fine tune it. Sometimes a simple efficiency test and air adjustment is all it needs. Other times pump pressure adjustments can help. But after the efficiency test they can determine whether the nozzle size needs to change some or air and draft corrections need to be made.