Oil fired Boiler Loud Bang on Start Up.

I have a new heating system, It is an oil heated Weil Mclian Gold Series with a Beckett Burner. The service guy replaced the original nozzle (after one year) with a 1 gal/hour nozzle. The original was 1.25 gal/hour. Now the system fires up with a bang. Also, what is this with the pump running for 30 seconds before it ignites ? Seems like a bad design. Doesn't the combustion chamber fill up with un burned fuel and then ignites? This is inherent in the design of these new systems; tey run for 30 seconds before ingition and then when the shut down the pump continue to run for 30 seconds. My old sysem didn't have this and there was never any loud bang when the oild ignited.
Also, I dont recall the bang noticeable when the burner had the 1.25 gal/hour nozzle.
Anyone have similar experiece?
M
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Sounds like it is set up wrong. The burner often runs before the oil as a pre-purge of the combustion chamber, then the ignition and fuel come on. Same with the post purge. As for the nozzle size, the depends on what your needs are as the burner can often accommodate a range of sizes. What you need is a competent service tech.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The new burners have a solenoid valve that opens to allow the oil in at the proper time. It's not spewing oil in the beginning of the cycle, just purging

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
m wrote:

The ignitor electrodes are most likely out of adjustment causing delayed ignition. Get the service guy to check and adjust them properly.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Go stand by the furnace and see what made the bang. My gas furnace also went bang, the bang being a metallic noise as in hitting the sheet metal sides with a fist. The bang occured during start-up as well as when the fan motor shut off and slowed down.
The cause was the squirrel cage fan that looked OK. So I took it out to see if there was anything I could fix as well as use the opportunity to clean up the insides. The shaft was deeply scoured. The bronze bearings ovalled. I replaced the 3/4 inch shaft and repaced the bearings. Worked fine for 15 years now.
In my earlier annual maintenance routine I had overtightened the fan belt. It should be tensioned with just the weight of the hinge mounted motor. The motor should be able to turn the fan without the belt slipping. I also added grease to the dry bronze bearings and periodically put in 10/30 motor oil to fix the squeaks and bangs. They worked for a time then I would have to repeat the exercise and tension the belt again. What happened was the heat had baked the grease hard and instead of lubricating the shaft it became a binder and an abrasive. That scoured the shaft and wore down the bearings. Motor oil lube made the problem worse as now there was a slurry of metal filings and oil to scour the metal. Tensioning the fan belt of course added to the wear rate.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
PaPaPeng wrote:

The OP apparently has a boiler (heats water), not a furnace (heats air), so there isn't a big blower or noisy sheet metal, there are cast iron boiler sections.
Almost certainly when the previous tech changed the nozzle to reduce the firing rate, he knocked the igniter electrodes out of alignment and this is causing a delayed ignition. Checking and adjusting the electrodes should fix the problem, and if it began immediately after the tech had changed the nozzle it should really be a no charge fix.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I have to agree with that. I'd also want to ask the tech WHY he changed the nozzle, and if he did, what are the angle specs of the old and the new nozzle, too? The ignitor electrodes of course do need to be checked, and specced for the new fuel delivery rate. The fuel delivery rate may also need an adjustment (psi adjustment). If all the tech did was change the nozzle, and especially if he frogged the electrodes, that's causing the bang. Since it sounds like a good loud bank, I'll also guess that your'e using #1 fuel or or kerosene(basically same thing) for fue. and not #2 oil. I say that simply because if it's #2 oil it's less likely to ignite, period, although it can still flash with a bang. The "problem" is too much atomized fuel collecting in the chamber which for some reason the ignitor can not ignite until the chamber gases fill it enough to finally ignite it with a relatively soft but noisy explosion. NOTE: Should the ignition fail more than about three times in a row, and start on say the 4th try, there could be a pretty considerable amount of fuel oil in the bottom of the chamber which, when ignited, will burn very very hot, with a whooshing sound, and if it's at night, probably show coming out of the chimney. If a pipe blows apart from it, you have an exposed flame possibility. This CAN be dangerous. Not IS, but CAN be! If the furnace starts and runs OK though, then anything in the bottom has burned off and is gone.
Anyway you can ask for one of their "better" technicians to come and take a look at it? Quickly? You shouldn't wait too long. Worst case, the bangs are creating a lot of soot, which will block the eye inside, and the furnace will quit running completely once that happens. Doesn't see fire after start, shuts off the fuel line; pops the little red button. Beware restart attempts after that point.
Best,
Pop`
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Since it sounds like a

#2 is less likely to light???!!!
You need to shut the fuck up when you don't know what you are talking about.....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote

I apologize for that. It was uncalled for. Typing out loud.
You need to shut the hell up when you don't know what you are talking about.....
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
There is no soot or smoke. The loud bang is not like an explosion. I't more like the flue pipe damper bangs when it starts up.
On Sat, 29 Dec 2007 20:00:25 GMT, "Dr. Hardcrab"

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hmmm, mine makes the same sound, I always thought it was normal. I do remember when my tech came out to clean it this year it was a little more quiet for a couple of days but then went back to the banging at startup.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Do you have a Becket Burner and Weil MClain Boiler?
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Yes, the same setup and the sound definitely comes from the force of air going through the vent to the chimney. My vent has a one way flap that I assume is there to keep the cold air from coming back down the chimney when the boiler is off. That's what makes the most noise.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

That's a better definition. It's still something that's likely to result from the late ignition though as the excess fuel ignites, causing lots of pressure, and then quickly settles back to "normal", rapidly decreasing the pressure and pulling the butterfly valve back with a bang, after which it begins to function normally.
BTW, while I'm thinking of it, if you're trying to watch this happen through the fireport, be careful; that first ignition could remove your eyebrows and eyelashes quite promptly, as at least one tech I know could tell you<g>. Mostly got his hair, but gave his forehead a sunburn; fortunately he was looking downward.
For the guy wondering about #2 fuel oil; it simply has a higher temp flash point and doesn't ignite as easily nor remain suspended in air nearly as well. That's all it meant. If you think it's misinformation, feel to correct it, but it is the case.
Pop`
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I have had this system fro two years now Last year when I was using the factory installed 1.25 gal/hr nozzle the bang didnt seem to be a problem. This season the tech droped it down to 1 gal hr and now I get the bang I had him come back once because the burner was running lousey it was loud and an oil odor. He replaced the nozzle with a differnt style nozzle. I think it was hollow vs solid.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.