Boiler Pipe

Got your notebooks? Ok here’s the deal….

The condition you have her is caused by the flue gases condensing. As MP stated, the problem lies within your fuel/air mixture and is pretty easily fixed. Call a qualified heating company and tell them the flue gases are condensing in the breeching. Now the fun stuff.

So why is this happening?

Well, let’s assume you are burning #2 fuel oil. There is almost 1 lb. of water created for every 1 lb of oil burned. Additionally there is or (actually) should be about 12% of CO2 in the gases as well as the “acids” that MP referred to which are specifically, NOx, SO2 and SO3. If you are condensing any of that water in the system it will cause exactly the problem you have here. The sucky thing is that this could even be happening at the top sections of your boiler which means you will be purchasing a new boiler sooner rather than later.

The amount of fuel you are burning is locked the BAR valve on larger boilers. On a small residential boiler the fuel is set by the nozzle size in terms of gallons per hour in the case of fuel oil and the orifice in the case of natural gas.

So what you want to do is set the air to give you the proper combustion. Ahhh but this is a tricky little thing because air in the summer is different from air in the winter. Yes. It is true. Even in Brooklyn where we have the sweetest air in the country. Trust me, I am a block from the Gowanus Canal.

So if you adjusted the amount of air to give you near perfect combustion today, August 26, on January 26 your flame would be burning WAY hot. Why? Because there is less humidity and slightly higher levels of oxygen in colder air due to it’s higher density.

For this reason we introduce an idea called excess air. Now excess air is important because it ensures your burner will have proper combustion on days that differ from the day you set up the burner to begin with. This stuff needs to be done with a tool called a flue gas analyzer.

For each 1% decrease in excess air levels introduced into the combustion process, the boiler’s efficiency increases by 1/4 to 1 of a percent. While some excess air is necessary to insure complete combustion, flue gas analysis will verify that excess air is within the manufacturer’s specifications and optimize efficient operation.

Boiler efficiency means money in your pocket. The cooler those flue gases the less heat going out your chimney and the more heat going into you water. However, get those gases too cool and you have condensation. So there it is.

Now my questions.

1- How long is that breeching? It looks like it is pretty long from the photo. Very long breeching runs should be insulated.

2- Are you burning oil or gas?

BTW the combustion process is the same no matter what you are burning.

3- Are you seeing smoke at the top of the chimney when your boiler lights off? Is it black? If you don’t have enough air going in, then you will see black smoke.

Please keep us posted.

Regards,

-SteamMan

Yes, it was clean — I did have a few issues during the Winter (forgot to mention) with a few parts being changed, boiler cutting off (the lighter going out). I third, fourth, etc. everyones comment re Master Plvmber. I’ll do better than suggest it to the plumber (obvious he doesn’t have a clue to the problem which means he won’t know how to fix it), I’m going to get in touch with you (I’m not kidding!) Thank you everyone!

I second Mopar’s comment. MP always has very clear, informative and positive things to say here.

did your plumber clean the chimney hen the boiler as changed out?.. looks like chimney blockage

It’s not water coming down your chimney. It’s water going up. There are two common problems that present themselves the way your picture shows:

1. You’ve got an air-fuel mixture problem in the boiler that is causing excess moisture in the flue gases. That moisture, being the result of the combustion of a carbon-based fuel (natural gas, oil, etc.), contains highly-corrosive carbonic acid. That acid is sticking to the inside walls of the flue pipe and disintegrating it.

2. You have a leak in the boiler that is turning into steam and following the path of the flue gases out to the chimney and oxidizing the pipe.

My hunch, without seeing more of the sitch, is it’s number 1.
Why? Because when rain gets into the chimney, it rolls along the bottom of the pipe and looks like any common plumbing drain leak. You don’t have that here. You’ve got rot and pinholes forming all around the pipe, especially around the seams where some of that flue gas is escaping. And yes, the picture also suggests you’re getting some carbon monoxide escaping into the home, too.
As for the second cause, you said the pipe or boiler is less than a year old. Most internal leaks, if they’re bad enough to create that kind of damage within a year, will also show up somewhere else; like on the floor or puffs of white smoke from the chimney at the roof.

What’s causing your combustion problem is probably either a lack of make-up air at the boiler (boilers need a whole bunch of fresh air to burn fuel completely and safely, big drafty cellars tend to work fine, tight ones need a duct to the outside) or a chimney that isn’t venting properly.

Of course, there are other causes, but if your plumber doesn’t know, then he’s probably not a very good heating guy and needs to take some classes in safe boiler operation.
Suggest that to him and see what he says. (I’m kidding. Don’t do that unless you know him real well)

Hope this helps.

Master Plvmber
http://www.GatewayPlumbing.com